Since hugetlb_follow_page_mask() walks the pgtable, it needs the vma lock
to make sure the pgtable page will not be freed concurrently.

Link: https://lkml.kernel.org/r/20221216155219.2043714-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We can take the hugetlb walker lock, here taking vma lock directly.

Link: https://lkml.kernel.org/r/20221216155217.2043700-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

In hugetlb_fault(), there used to have a special path to handle swap entry
at the entrance using huge_pte_offset().  That's unsafe because
huge_pte_offset() for a pmd sharable range can access freed pgtables if
without any lock to protect the pgtable from being freed after pmd
unshare.

Here the simplest solution to make it safe is to move the swap handling to
be after the vma lock being held.  We may need to take the fault mutex on
either migration or hwpoison entries now (also the vma lock, but that's
really needed), however neither of them is hot path.

Note that the vma lock cannot be released in hugetlb_fault() when the
migration entry is detected, because in migration_entry_wait_huge() the
pgtable page will be used again (by taking the pgtable lock), so that also
need to be protected by the vma lock.  Modify migration_entry_wait_huge()
so that it must be called with vma read lock held, and properly release
the lock in __migration_entry_wait_huge().

Link: https://lkml.kernel.org/r/20221216155100.2043537-5-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

huge_pte_offset() is potentially a pgtable walker, looking up pte_t* for a
hugetlb address.

Normally, it's always safe to walk a generic pgtable as long as we're with
the mmap lock held for either read or write, because that guarantees the
pgtable pages will always be valid during the process.

But it's not true for hugetlbfs, especially shared: hugetlbfs can have its
pgtable freed by pmd unsharing, it means that even with mmap lock held for
current mm, the PMD pgtable page can still go away from under us if pmd
unsharing is possible during the walk.

So we have two ways to make it safe even for a shared mapping:

  (1) If we're with the hugetlb vma lock held for either read/write, it's
      okay because pmd unshare cannot happen at all.

  (2) If we're with the i_mmap_rwsem lock held for either read/write, it's
      okay because even if pmd unshare can happen, the pgtable page cannot
      be freed from under us.

Document it.

Link: https://lkml.kernel.org/r/20221216155100.2043537-4-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

That's what the code does with !hugetlb pages, so we should logically do
the same for hugetlb, so migration entry will also be treated as no page.

This is probably also the last piece in follow_page code that may sleep,
the last one should be removed in cf994dd8af27 ("mm/gup: remove
FOLL_MIGRATION", 2022-11-16).

Link: https://lkml.kernel.org/r/20221216155100.2043537-3-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm/hugetlb: Make huge_pte_offset() thread-safe for pmd
unshare", v4.

Problem
=======

huge_pte_offset() is a major helper used by hugetlb code paths to walk a
hugetlb pgtable.  It's used mostly everywhere since that's needed even
before taking the pgtable lock.

huge_pte_offset() is always called with mmap lock held with either read or
write.  It was assumed to be safe but it's actually not.  One race
condition can easily trigger by: (1) firstly trigger pmd share on a memory
range, (2) do huge_pte_offset() on the range, then at the meantime, (3)
another thread unshare the pmd range, and the pgtable page is prone to lost
if the other shared process wants to free it completely (by either munmap
or exit mm).

The recent work from Mike on vma lock can resolve most of this already.
It's achieved by forbidden pmd unsharing during the lock being taken, so no
further risk of the pgtable page being freed.  It means if we can take the
vma lock around all huge_pte_offset() callers it'll be safe.

There're already a bunch of them that we did as per the latest mm-unstable,
but also quite a few others that we didn't for various reasons especially
on huge_pte_offset() usage.

One more thing to mention is that besides the vma lock, i_mmap_rwsem can
also be used to protect the pgtable page (along with its pgtable lock) from
being freed from under us.  IOW, huge_pte_offset() callers need to either
hold the vma lock or i_mmap_rwsem to safely walk the pgtables.

A reproducer of such problem, based on hugetlb GUP (NOTE: since the race is
very hard to trigger, one needs to apply another kernel delay patch too,
see below):

======8<=======
  #define _GNU_SOURCE
  #include <stdio.h>
  #include <stdlib.h>
  #include <errno.h>
  #include <unistd.h>
  #include <sys/mman.h>
  #include <fcntl.h>
  #include <linux/memfd.h>
  #include <assert.h>
  #include <pthread.h>

  #define  MSIZE  (1UL << 30)     /* 1GB */
  #define  PSIZE  (2UL << 20)     /* 2MB */

  #define  HOLD_SEC  (1)

  int pipefd[2];
  void *buf;

  void *do_map(int fd)
  {
      unsigned char *tmpbuf, *p;
      int ret;

      ret = posix_memalign((void **)&tmpbuf, MSIZE, MSIZE);
      if (ret) {
          perror("posix_memalign() failed");
          return NULL;
      }

      tmpbuf = mmap(tmpbuf, MSIZE, PROT_READ | PROT_WRITE,
                    MAP_SHARED | MAP_FIXED, fd, 0);
      if (tmpbuf == MAP_FAILED) {
          perror("mmap() failed");
          return NULL;
      }
      printf("mmap() -> %p\n", tmpbuf);

      for (p = tmpbuf; p < tmpbuf + MSIZE; p += PSIZE) {
          *p = 1;
      }

      return tmpbuf;
  }

  void do_unmap(void *buf)
  {
      munmap(buf, MSIZE);
  }

  void proc2(int fd)
  {
      unsigned char c;

      buf = do_map(fd);
      if (!buf)
          return;

      read(pipefd[0], &c, 1);
      /*
       * This frees the shared pgtable page, causing use-after-free in
       * proc1_thread1 when soft walking hugetlb pgtable.
       */
      do_unmap(buf);

      printf("Proc2 quitting\n");
  }

  void *proc1_thread1(void *data)
  {
      /*
       * Trigger follow-page on 1st 2m page.  Kernel hack patch needed to
       * withhold this procedure for easier reproduce.
       */
      madvise(buf, PSIZE, MADV_POPULATE_WRITE);
      printf("Proc1-thread1 quitting\n");
      return NULL;
  }

  void *proc1_thread2(void *data)
  {
      unsigned char c;

      /* Wait a while until proc1_thread1() start to wait */
      sleep(0.5);
      /* Trigger pmd unshare */
      madvise(buf, PSIZE, MADV_DONTNEED);
      /* Kick off proc2 to release the pgtable */
      write(pipefd[1], &c, 1);

      printf("Proc1-thread2 quitting\n");
      return NULL;
  }

  void proc1(int fd)
  {
      pthread_t tid1, tid2;
      int ret;

      buf = do_map(fd);
      if (!buf)
          return;

      ret = pthread_create(&tid1, NULL, proc1_thread1, NULL);
      assert(ret == 0);
      ret = pthread_create(&tid2, NULL, proc1_thread2, NULL);
      assert(ret == 0);

      /* Kick the child to share the PUD entry */
      pthread_join(tid1, NULL);
      pthread_join(tid2, NULL);

      do_unmap(buf);
  }

  int main(void)
  {
      int fd, ret;

      fd = memfd_create("test-huge", MFD_HUGETLB | MFD_HUGE_2MB);
      if (fd < 0) {
          perror("open failed");
          return -1;
      }

      ret = ftruncate(fd, MSIZE);
      if (ret) {
          perror("ftruncate() failed");
          return -1;
      }

      ret = pipe(pipefd);
      if (ret) {
          perror("pipe() failed");
          return -1;
      }

      if (fork()) {
          proc1(fd);
      } else {
          proc2(fd);
      }

      close(pipefd[0]);
      close(pipefd[1]);
      close(fd);

      return 0;
  }
======8<=======

The kernel patch needed to present such a race so it'll trigger 100%:

======8<=======
: diff --git a/mm/hugetlb.c b/mm/hugetlb.c
: index 9d97c9a2a15d..f8d99dad5004 100644
: --- a/mm/hugetlb.c
: +++ b/mm/hugetlb.c
: @@ -38,6 +38,7 @@
:  #include <asm/page.h>
:  #include <asm/pgalloc.h>
:  #include <asm/tlb.h>
: +#include <asm/delay.h>
: 
:  #include <linux/io.h>
:  #include <linux/hugetlb.h>
: @@ -6290,6 +6291,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
:                 bool unshare = false;
:                 int absent;
:                 struct page *page;
: +               unsigned long c = 0;
: 
:                 /*
:                  * If we have a pending SIGKILL, don't keep faulting pages and
: @@ -6309,6 +6311,13 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
:                  */
:                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
:                                       huge_page_size(h));
: +
: +               pr_info("%s: withhold 1 sec...\n", __func__);
: +               for (c = 0; c < 100; c++) {
: +                       udelay(10000);
: +               }
: +               pr_info("%s: withhold 1 sec...done\n", __func__);
: +
:                 if (pte)
:                         ptl = huge_pte_lock(h, mm, pte);
:                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
: ======8<=======

It'll trigger use-after-free of the pgtable spinlock:

======8<=======
[   16.959907] follow_hugetlb_page: withhold 1 sec...
[   17.960315] follow_hugetlb_page: withhold 1 sec...done
[   17.960550] ------------[ cut here ]------------
[   17.960742] DEBUG_LOCKS_WARN_ON(1)
[   17.960756] WARNING: CPU: 3 PID: 542 at kernel/locking/lockdep.c:231 __lock_acquire+0x955/0x1fa0
[   17.961264] Modules linked in:
[   17.961394] CPU: 3 PID: 542 Comm: hugetlb-pmd-sha Not tainted 6.1.0-rc4-peterx+ #46
[   17.961704] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
[   17.962266] RIP: 0010:__lock_acquire+0x955/0x1fa0
[   17.962516] Code: c0 0f 84 5f fe ff ff 44 8b 1d 0f 9a 29 02 45 85 db 0f 85 4f fe ff ff 48 c7 c6 75 50 83 82 48 c7 c7 1b 4b 7d 82 e8 d3 22 d8 00 <0f> 0b 31 c0 4c 8b 54 24 08 4c 8b 04 24 e9
[   17.963494] RSP: 0018:ffffc90000e4fba8 EFLAGS: 00010096
[   17.963704] RAX: 0000000000000016 RBX: fffffffffd3925a8 RCX: 0000000000000000
[   17.963989] RDX: 0000000000000002 RSI: ffffffff82863ccf RDI: 00000000ffffffff
[   17.964276] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffc90000e4fa58
[   17.964557] R10: 0000000000000003 R11: ffffffff83162688 R12: 0000000000000000
[   17.964839] R13: 0000000000000001 R14: ffff888105eac748 R15: 0000000000000001
[   17.965123] FS:  00007f17c0a00640(0000) GS:ffff888277cc0000(0000) knlGS:0000000000000000
[   17.965443] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   17.965672] CR2: 00007f17c09ffef8 CR3: 000000010c87a005 CR4: 0000000000770ee0
[   17.965956] PKRU: 55555554
[   17.966068] Call Trace:
[   17.966172]  <TASK>
[   17.966268]  ? tick_nohz_tick_stopped+0x12/0x30
[   17.966455]  lock_acquire+0xbf/0x2b0
[   17.966603]  ? follow_hugetlb_page.cold+0x75/0x5c4
[   17.966799]  ? _printk+0x48/0x4e
[   17.966934]  _raw_spin_lock+0x2f/0x40
[   17.967087]  ? follow_hugetlb_page.cold+0x75/0x5c4
[   17.967285]  follow_hugetlb_page.cold+0x75/0x5c4
[   17.967473]  __get_user_pages+0xbb/0x620
[   17.967635]  faultin_vma_page_range+0x9a/0x100
[   17.967817]  madvise_vma_behavior+0x3c0/0xbd0
[   17.967998]  ? mas_prev+0x11/0x290
[   17.968141]  ? find_vma_prev+0x5e/0xa0
[   17.968304]  ? madvise_vma_anon_name+0x70/0x70
[   17.968486]  madvise_walk_vmas+0xa9/0x120
[   17.968650]  do_madvise.part.0+0xfa/0x270
[   17.968813]  __x64_sys_madvise+0x5a/0x70
[   17.968974]  do_syscall_64+0x37/0x90
[   17.969123]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   17.969329] RIP: 0033:0x7f1840f0efdb
[   17.969477] Code: c3 66 0f 1f 44 00 00 48 8b 15 39 6e 0e 00 f7 d8 64 89 02 b8 ff ff ff ff eb bc 0f 1f 44 00 00 f3 0f 1e fa b8 1c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 0d 68
[   17.970205] RSP: 002b:00007f17c09ffe38 EFLAGS: 00000202 ORIG_RAX: 000000000000001c
[   17.970504] RAX: ffffffffffffffda RBX: 00007f17c0a00640 RCX: 00007f1840f0efdb
[   17.970786] RDX: 0000000000000017 RSI: 0000000000200000 RDI: 00007f1800000000
[   17.971068] RBP: 00007f17c09ffe50 R08: 0000000000000000 R09: 00007ffd3954164f
[   17.971353] R10: 00007f1840e10348 R11: 0000000000000202 R12: ffffffffffffff80
[   17.971709] R13: 0000000000000000 R14: 00007ffd39541550 R15: 00007f17c0200000
[   17.972083]  </TASK>
[   17.972199] irq event stamp: 2353
[   17.972372] hardirqs last  enabled at (2353): [<ffffffff8117fe4e>] __up_console_sem+0x5e/0x70
[   17.972869] hardirqs last disabled at (2352): [<ffffffff8117fe33>] __up_console_sem+0x43/0x70
[   17.973365] softirqs last  enabled at (2330): [<ffffffff810f763d>] __irq_exit_rcu+0xed/0x160
[   17.973857] softirqs last disabled at (2323): [<ffffffff810f763d>] __irq_exit_rcu+0xed/0x160
[   17.974341] ---[ end trace 0000000000000000 ]---
[   17.974614] BUG: kernel NULL pointer dereference, address: 00000000000000b8
[   17.975012] #PF: supervisor read access in kernel mode
[   17.975314] #PF: error_code(0x0000) - not-present page
[   17.975615] PGD 103f7b067 P4D 103f7b067 PUD 106cd7067 PMD 0
[   17.975943] Oops: 0000 [#1] PREEMPT SMP NOPTI
[   17.976197] CPU: 3 PID: 542 Comm: hugetlb-pmd-sha Tainted: G        W          6.1.0-rc4-peterx+ #46
[   17.976712] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
[   17.977370] RIP: 0010:__lock_acquire+0x190/0x1fa0
[   17.977655] Code: 98 00 00 00 41 89 46 24 81 e2 ff 1f 00 00 48 0f a3 15 e4 ba dd 02 0f 83 ff 05 00 00 48 8d 04 52 48 c1 e0 06 48 05 c0 d2 f4 83 <44> 0f b6 a0 b8 00 00 00 41 0f b7 46 20 6f
[   17.979170] RSP: 0018:ffffc90000e4fba8 EFLAGS: 00010046
[   17.979787] RAX: 0000000000000000 RBX: fffffffffd3925a8 RCX: 0000000000000000
[   17.980838] RDX: 0000000000000002 RSI: ffffffff82863ccf RDI: 00000000ffffffff
[   17.982048] RBP: 0000000000000000 R08: ffff888105eac720 R09: ffffc90000e4fa58
[   17.982892] R10: ffff888105eab900 R11: ffffffff83162688 R12: 0000000000000000
[   17.983771] R13: 0000000000000001 R14: ffff888105eac748 R15: 0000000000000001
[   17.984815] FS:  00007f17c0a00640(0000) GS:ffff888277cc0000(0000) knlGS:0000000000000000
[   17.985924] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   17.986265] CR2: 00000000000000b8 CR3: 000000010c87a005 CR4: 0000000000770ee0
[   17.986674] PKRU: 55555554
[   17.986832] Call Trace:
[   17.987012]  <TASK>
[   17.987266]  ? tick_nohz_tick_stopped+0x12/0x30
[   17.987770]  lock_acquire+0xbf/0x2b0
[   17.988118]  ? follow_hugetlb_page.cold+0x75/0x5c4
[   17.988575]  ? _printk+0x48/0x4e
[   17.988889]  _raw_spin_lock+0x2f/0x40
[   17.989243]  ? follow_hugetlb_page.cold+0x75/0x5c4
[   17.989687]  follow_hugetlb_page.cold+0x75/0x5c4
[   17.990119]  __get_user_pages+0xbb/0x620
[   17.990500]  faultin_vma_page_range+0x9a/0x100
[   17.990928]  madvise_vma_behavior+0x3c0/0xbd0
[   17.991354]  ? mas_prev+0x11/0x290
[   17.991678]  ? find_vma_prev+0x5e/0xa0
[   17.992024]  ? madvise_vma_anon_name+0x70/0x70
[   17.992421]  madvise_walk_vmas+0xa9/0x120
[   17.992793]  do_madvise.part.0+0xfa/0x270
[   17.993166]  __x64_sys_madvise+0x5a/0x70
[   17.993539]  do_syscall_64+0x37/0x90
[   17.993879]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
======8<=======

Resolution
==========

This patchset protects all the huge_pte_offset() callers to also take the
vma lock properly.

Patch Layout
============

Patch 1-2:         cleanup, or dependency of the follow up patches
Patch 3:           before fixing, document huge_pte_offset() on lock required
Patch 4-8:         each patch resolves one possible race condition
Patch 9:           introduce hugetlb_walk() to replace huge_pte_offset()

Tests
=====

The series is verified with the above reproducer so the race cannot
trigger anymore.  It also passes all hugetlb kselftests.


This patch (of 9):

Even though vma_offset_start() is named like that, it's not returning "the
start address of the range" but rather the offset we should use to offset
the vma->vm_start address.

Make it return the real value of the start vaddr, and it also helps for
all the callers because whenever the retval is used, it'll be ultimately
added into the vma->vm_start anyway, so it's better.

Link: https://lkml.kernel.org/r/20221216155100.2043537-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20221216155100.2043537-2-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The check for whether a hugetlb vma lock exists partially depends on the
vma's flags.  Currently, it checks for either VM_MAYSHARE or VM_SHARED. 
The reason both flags are used is because VM_MAYSHARE was previously
cleared in hugetlb vmas as they are tore down.  This is no longer the
case, and only the VM_MAYSHARE check is required.

Link: https://lkml.kernel.org/r/20221212235042.178355-2-mike.kravetz@oracle.comSigned-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Tests to verify MFD_NOEXEC, MFD_EXEC and vm.memfd_noexec sysctl.

Link: https://lkml.kernel.org/r/20221215001205.51969-6-jeffxu@google.comSigned-off-by: Jeff Xu <jeffxu@google.com>
Co-developed-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: kernel test robot <lkp@intel.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

In order to avoid WX mappings, add F_SEAL_WRITE when apply F_SEAL_EXEC to
an executable memfd, so W^X from start.

This implys application need to fill the content of the memfd first, after
F_SEAL_EXEC is applied, application can no longer modify the content of
the memfd.

Typically, application seals the memfd right after writing to it.
For example:
1. memfd_create(MFD_EXEC).
2. write() code to the memfd.
3. fcntl(F_ADD_SEALS, F_SEAL_EXEC) to convert the memfd to W^X.
4. call exec() on the memfd.

Link: https://lkml.kernel.org/r/20221215001205.51969-5-jeffxu@google.comSigned-off-by: Jeff Xu <jeffxu@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Verkamp <dverkamp@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: kernel test robot <lkp@intel.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to set
executable bit at creation time (memfd_create).

When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
(mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to be
executable (mode: 0777) after creation.

when MFD_EXEC flag is set, memfd is created with executable bit
(mode:0777), this is the same as the old behavior of memfd_create.

The new pid namespaced sysctl vm.memfd_noexec has 3 values:
0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
        MFD_EXEC was set.
1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
        MFD_NOEXEC_SEAL was set.
2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.

The sysctl allows finer control of memfd_create for old-software that
doesn't set the executable bit, for example, a container with
vm.memfd_noexec=1 means the old-software will create non-executable memfd
by default.  Also, the value of memfd_noexec is passed to child namespace
at creation time.  For example, if the init namespace has
vm.memfd_noexec=2, all its children namespaces will be created with 2.

[akpm@linux-foundation.org: add stub functions to fix build]
[akpm@linux-foundation.org: remove unneeded register_pid_ns_ctl_table_vm() stub, per Jeff]
[akpm@linux-foundation.org: s/pr_warn_ratelimited/pr_warn_once/, per review]
[akpm@linux-foundation.org: fix CONFIG_SYSCTL=n warning]
Link: https://lkml.kernel.org/r/20221215001205.51969-4-jeffxu@google.comSigned-off-by: Jeff Xu <jeffxu@google.com>
Co-developed-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Basic tests to ensure that user/group/other execute bits cannot be changed
after applying F_SEAL_EXEC to a memfd.

Link: https://lkml.kernel.org/r/20221215001205.51969-3-jeffxu@google.comSigned-off-by: Daniel Verkamp <dverkamp@chromium.org>
Co-developed-by: Jeff Xu <jeffxu@google.com>
Signed-off-by: Jeff Xu <jeffxu@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: kernel test robot <lkp@intel.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC", v8.

Since Linux introduced the memfd feature, memfd have always had their
execute bit set, and the memfd_create() syscall doesn't allow setting it
differently.

However, in a secure by default system, such as ChromeOS, (where all
executables should come from the rootfs, which is protected by Verified
boot), this executable nature of memfd opens a door for NoExec bypass and
enables “confused deputy attack”.  E.g, in VRP bug [1]: cros_vm
process created a memfd to share the content with an external process,
however the memfd is overwritten and used for executing arbitrary code and
root escalation.  [2] lists more VRP in this kind.

On the other hand, executable memfd has its legit use, runc uses memfd’s
seal and executable feature to copy the contents of the binary then
execute them, for such system, we need a solution to differentiate runc's
use of executable memfds and an attacker's [3].

To address those above, this set of patches add following:
1> Let memfd_create() set X bit at creation time.
2> Let memfd to be sealed for modifying X bit.
3> A new pid namespace sysctl: vm.memfd_noexec to control the behavior of
   X bit.For example, if a container has vm.memfd_noexec=2, then
   memfd_create() without MFD_NOEXEC_SEAL will be rejected.
4> A new security hook in memfd_create(). This make it possible to a new
   LSM, which rejects or allows executable memfd based on its security policy.


This patch (of 5):

The new F_SEAL_EXEC flag will prevent modification of the exec bits:
written as traditional octal mask, 0111, or as named flags, S_IXUSR |
S_IXGRP | S_IXOTH.  Any chmod(2) or similar call that attempts to modify
any of these bits after the seal is applied will fail with errno EPERM.

This will preserve the execute bits as they are at the time of sealing, so
the memfd will become either permanently executable or permanently
un-executable.

Link: https://lkml.kernel.org/r/20221215001205.51969-1-jeffxu@google.com
Link: https://lkml.kernel.org/r/20221215001205.51969-2-jeffxu@google.comSigned-off-by: Daniel Verkamp <dverkamp@chromium.org>
Co-developed-by: Jeff Xu <jeffxu@google.com>
Signed-off-by: Jeff Xu <jeffxu@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This patch is a cleanup to always wr-protect pte/pmd in mkuffd_wp paths.

The reasons I still think this patch is worthwhile, are:

  (1) It is a cleanup already; diffstat tells.

  (2) It just feels natural after I thought about this, if the pte is uffd
      protected, let's remove the write bit no matter what it was.

  (2) Since x86 is the only arch that supports uffd-wp, it also redefines
      pte|pmd_mkuffd_wp() in that it should always contain removals of
      write bits.  It means any future arch that want to implement uffd-wp
      should naturally follow this rule too.  It's good to make it a
      default, even if with vm_page_prot changes on VM_UFFD_WP.

  (3) It covers more than vm_page_prot.  So no chance of any potential
      future "accident" (like pte_mkdirty() sparc64 or loongarch, even
      though it just got its pte_mkdirty fixed <1 month ago).  It'll be
      fairly clear when reading the code too that we don't worry anything
      before a pte_mkuffd_wp() on uncertainty of the write bit.

We may call pte_wrprotect() one more time in some paths (e.g.  thp split),
but that should be fully local bitop instruction so the overhead should be
negligible.

Although this patch should logically also fix all the known issues on
uffd-wp too recently on page migration (not for numa hint recovery - that
may need another explcit pte_wrprotect), but this is not the plan for that
fix.  So no fixes, and stable doesn't need this.

Link: https://lkml.kernel.org/r/20221214201533.1774616-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ives van Hoorne <ives@codesandbox.io>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

folio_set_compound_order() is moved to an mm-internal location so external
folio users cannot misuse this function.  Change the name of the function
to folio_set_order() and use WARN_ON_ONCE() rather than BUG_ON.  Also,
handle the case if a non-large folio is passed and add clarifying comments
to the function.

Link: https://lore.kernel.org/lkml/20221207223731.32784-1-sidhartha.kumar@oracle.com/T/
Link: https://lkml.kernel.org/r/20221215061757.223440-1-sidhartha.kumar@oracle.com
Fixes: 9fd33058 ("mm: add folio dtor and order setter functions")
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Muchun Song <songmuchun@bytedance.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Merge branch 'mm-hotfixes-stable' into mm-stable

This patch should harden commit 15520a3f ("mm: use pte markers for
swap errors") on using pte markers for swapin errors on a few corner
cases.

1. Propagate swapin errors across fork()s: if there're swapin errors in
   the parent mm, after fork()s the child should sigbus too when an error
   page is accessed.

2. Fix a rare condition race in pte_marker_clear() where a uffd-wp pte
   marker can be quickly switched to a swapin error.

3. Explicitly ignore swapin error pte markers in change_protection().

I mostly don't worry on (2) or (3) at all, but we should still have them. 
Case (1) is special because it can potentially cause silent data corrupt
on child when parent has swapin error triggered with swapoff, but since
swapin error is rare itself already it's probably not easy to trigger
either.

Currently there is a priority difference between the uffd-wp bit and the
swapin error entry, in which the swapin error always has higher priority
(e.g.  we don't need to wr-protect a swapin error pte marker).

If there will be a 3rd bit introduced, we'll probably need to consider a
more involved approach so we may need to start operate on the bits.  Let's
leave that for later.

This patch is tested with case (1) explicitly where we'll get corrupted
data before in the child if there's existing swapin error pte markers, and
after patch applied the child can be rightfully killed.

We don't need to copy stable for this one since 15520a3f just landed
as part of v6.2-rc1, only "Fixes" applied.

Link: https://lkml.kernel.org/r/20221214200453.1772655-3-peterx@redhat.com
Fixes: 15520a3f ("mm: use pte markers for swap errors")
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm: Fixes on pte markers".

Patch 1 resolves the syzkiller report from Pengfei.

Patch 2 further harden pte markers when used with the recent swapin error
markers.  The major case is we should persist a swapin error marker after
fork(), so child shouldn't read a corrupted page.


This patch (of 2):

When fork(), dst_vma is not guaranteed to have VM_UFFD_WP even if src may
have it and has pte marker installed.  The warning is improper along with
the comment.  The right thing is to inherit the pte marker when needed, or
keep the dst pte empty.

A vague guess is this happened by an accident when there's the prior patch
to introduce src/dst vma into this helper during the uffd-wp feature got
developed and I probably messed up in the rebase, since if we replace
dst_vma with src_vma the warning & comment it all makes sense too.

Hugetlb did exactly the right here (copy_hugetlb_page_range()).  Fix the
general path.

Reproducer:

https://github.com/xupengfe/syzkaller_logs/blob/main/221208_115556_copy_page_range/repro.c

Bugzilla report: https://bugzilla.kernel.org/show_bug.cgi?id=216808

Link: https://lkml.kernel.org/r/20221214200453.1772655-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20221214200453.1772655-2-peterx@redhat.com
Fixes: c56d1b62 ("mm/shmem: handle uffd-wp during fork()")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: <stable@vger.kernel.org> # 5.19+
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Merge branch 'master' into mm-hotfixes-stable

Merge branch 'master' into mm-stable

Pull x86 fixes from Borislav Petkov:

 - Make sure the poking PGD is pinned for Xen PV as it requires it this
   way

 - Fixes for two resctrl races when moving a task or creating a new
   monitoring group

 - Fix SEV-SNP guests running under HyperV where MTRRs are disabled to
   not return a UC- type mapping type on memremap() and thus cause a
   serious slowdown

 - Fix insn mnemonics in bioscall.S now that binutils is starting to fix
   confusing insn suffixes

* tag 'x86_urgent_for_v6.2_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: fix poking_init() for Xen PV guests
  x86/resctrl: Fix event counts regression in reused RMIDs
  x86/resctrl: Fix task CLOSID/RMID update race
  x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case
  x86/boot: Avoid using Intel mnemonics in AT&T syntax asm

Pull EDAC fixes from Borislav Petkov:

 - Fix the EDAC device's confusion in the polling setting units

 - Fix a memory leak in highbank's probing function

* tag 'edac_urgent_for_v6.2_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras:
  EDAC/highbank: Fix memory leak in highbank_mc_probe()
  EDAC/device: Fix period calculation in edac_device_reset_delay_period()

Pull powerpc fixes from Michael Ellerman:

 - Fix a build failure with some versions of ld that have an odd version
   string

 - Fix incorrect use of mutex in the IMC PMU driver

Thanks to Kajol Jain, Michael Petlan, Ojaswin Mujoo, Peter Zijlstra, and
Yang Yingliang.

* tag 'powerpc-6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s/hash: Make stress_hpt_timer_fn() static
  powerpc/imc-pmu: Fix use of mutex in IRQs disabled section
  powerpc/boot: Fix incorrect version calculation issue in ld_version

Pull iommu fixes from Joerg Roedel:

 - Core: Fix an iommu-group refcount leak

 - Fix overflow issue in IOVA alloc path

 - ARM-SMMU fixes from Will:
    - Fix VFIO regression on NXP SoCs by reporting IOMMU_CAP_CACHE_COHERENCY
    - Fix SMMU shutdown paths to avoid device unregistration race

 - Error handling fix for Mediatek IOMMU driver

* tag 'iommu-fixes-v6.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/mediatek-v1: Fix an error handling path in mtk_iommu_v1_probe()
  iommu/iova: Fix alloc iova overflows issue
  iommu: Fix refcount leak in iommu_device_claim_dma_owner
  iommu/arm-smmu-v3: Don't unregister on shutdown
  iommu/arm-smmu: Don't unregister on shutdown
  iommu/arm-smmu: Report IOMMU_CAP_CACHE_COHERENCY even betterer

Pull memblock fix from Mike Rapoport:
 "memblock: always release pages to the buddy allocator in
  memblock_free_late()

  If CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, memblock_free_pages()
  only releases pages to the buddy allocator if they are not in the
  deferred range. This is correct for free pages (as defined by
  for_each_free_mem_pfn_range_in_zone()) because free pages in the
  deferred range will be initialized and released as part of the
  deferred init process.

  memblock_free_pages() is called by memblock_free_late(), which is used
  to free reserved ranges after memblock_free_all() has run. All pages
  in reserved ranges have been initialized at that point, and
  accordingly, those pages are not touched by the deferred init process.

  This means that currently, if the pages that memblock_free_late()
  intends to release are in the deferred range, they will never be
  released to the buddy allocator. They will forever be reserved.

  In addition, memblock_free_pages() calls kmsan_memblock_free_pages(),
  which is also correct for free pages but is not correct for reserved
  pages. KMSAN metadata for reserved pages is initialized by
  kmsan_init_shadow(), which runs shortly before memblock_free_all().

  For both of these reasons, memblock_free_pages() should only be called
  for free pages, and memblock_free_late() should call
  __free_pages_core() directly instead.

  One case where this issue can occur in the wild is EFI boot on x86_64.
  The x86 EFI code reserves all EFI boot services memory ranges via
  memblock_reserve() and frees them later via memblock_free_late()
  (efi_reserve_boot_services() and efi_free_boot_services(),
  respectively).

  If any of those ranges happens to fall within the deferred init range,
  the pages will not be released and that memory will be unavailable.

  For example, on an Amazon EC2 t3.micro VM (1 GB) booting via EFI:

    v6.2-rc2:
    Node 0, zone      DMA
          spanned  4095
          present  3999
          managed  3840
    Node 0, zone    DMA32
          spanned  246652
          present  245868
          managed  178867

    v6.2-rc2 + patch:
    Node 0, zone      DMA
          spanned  4095
          present  3999
          managed  3840
    Node 0, zone    DMA32
          spanned  246652
          present  245868
          managed  222816   # +43,949 pages"

* tag 'fixes-2023-01-14' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
  mm: Always release pages to the buddy allocator in memblock_free_late().

Pull kernel hardening fixes from Kees Cook:

 - Fix CFI hash randomization with KASAN (Sami Tolvanen)

 - Check size of coreboot table entry and use flex-array

* tag 'hardening-v6.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  kbuild: Fix CFI hash randomization with KASAN
  firmware: coreboot: Check size of table entry and use flex-array

Pull module fix from Luis Chamberlain:
 "Just one fix for modules by Nick"

* tag 'modules-6.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  kallsyms: Fix scheduling with interrupts disabled in self-test

Pull cifs fixes from Steve French:

 - memory leak and double free fix

 - two symlink fixes

 - minor cleanup fix

 - two smb1 fixes

* tag '6.2-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Fix uninitialized memory read for smb311 posix symlink create
  cifs: fix potential memory leaks in session setup
  cifs: do not query ifaces on smb1 mounts
  cifs: fix double free on failed kerberos auth
  cifs: remove redundant assignment to the variable match
  cifs: fix file info setting in cifs_open_file()
  cifs: fix file info setting in cifs_query_path_info()

Pull SCSI fixes from James Bottomley:
 "Two minor fixes in the hisi_sas driver which only impact enterprise
  style multi-expander and shared disk situations and no core changes"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: hisi_sas: Set a port invalid only if there are no devices attached when refreshing port id
  scsi: hisi_sas: Use abort task set to reset SAS disks when discovered

Pull ATA fix from Damien Le Moal:
 "A single fix to prevent building the pata_cs5535 driver with user mode
  linux as it uses msr operations that are not defined with UML"

* tag 'ata-6.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: pata_cs5535: Don't build on UML

Pull block fixes from Jens Axboe:
 "Nothing major in here, just a collection of NVMe fixes and dropping a
  wrong might_sleep() that static checkers tripped over but which isn't
  valid"

* tag 'block-6.2-2023-01-13' of git://git.kernel.dk/linux:
  MAINTAINERS: stop nvme matching for nvmem files
  nvme: don't allow unprivileged passthrough on partitions
  nvme: replace the "bool vec" arguments with flags in the ioctl path
  nvme: remove __nvme_ioctl
  nvme-pci: fix error handling in nvme_pci_enable()
  nvme-pci: add NVME_QUIRK_IDENTIFY_CNS quirk to Apple T2 controllers
  nvme-apple: add NVME_QUIRK_IDENTIFY_CNS quirk to fix regression
  block: Drop spurious might_sleep() from blk_put_queue()

Pull io_uring fixes from Jens Axboe:
 "A fix for a regression that happened last week, rest is fixes that
  will be headed to stable as well. In detail:

   - Fix for a regression added with the leak fix from last week (me)

   - In writing a test case for that leak, inadvertently discovered a
     case where we a poll request can race. So fix that up and mark it
     for stable, and also ensure that fdinfo covers both the poll tables
     that we have. The latter was an oversight when the split poll table
     were added (me)

   - Fix for a lockdep reported issue with IOPOLL (Pavel)"

* tag 'io_uring-6.2-2023-01-13' of git://git.kernel.dk/linux:
  io_uring: lock overflowing for IOPOLL
  io_uring/poll: attempt request issue after racy poll wakeup
  io_uring/fdinfo: include locked hash table in fdinfo output
  io_uring/poll: add hash if ready poll request can't complete inline
  io_uring/io-wq: only free worker if it was allocated for creation

Pull pci fixes from Bjorn Helgaas:

 - Work around apparent firmware issue that made Linux reject MMCONFIG
   space, which broke PCI extended config space (Bjorn Helgaas)

 - Fix CONFIG_PCIE_BT1 dependency due to mid-air collision between a
   PCI_MSI_IRQ_DOMAIN -> PCI_MSI change and addition of PCIE_BT1 (Lukas
   Bulwahn)

* tag 'pci-v6.2-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space
  x86/pci: Simplify is_mmconf_reserved() messages
  PCI: dwc: Adjust to recent removal of PCI_MSI_IRQ_DOMAIN

Clang emits a asan.module_ctor constructor to each object file
when KASAN is enabled, and these functions are indirectly called
in do_ctors. With CONFIG_CFI_CLANG, the compiler also emits a CFI
type hash before each address-taken global function so they can
pass indirect call checks.

However, in commit 0c3e806e ("x86/cfi: Add boot time hash
randomization"), x86 implemented boot time hash randomization,
which relies on the .cfi_sites section generated by objtool. As
objtool is run against vmlinux.o instead of individual object
files with X86_KERNEL_IBT (enabled by default), CFI types in
object files that are not part of vmlinux.o end up not being
included in .cfi_sites, and thus won't get randomized and trip
CFI when called.

Only .vmlinux.export.o and init/version-timestamp.o are linked
into vmlinux separately from vmlinux.o. As these files don't
contain any functions, disable KASAN for both of them to avoid
breaking hash randomization.

Link: https://github.com/ClangBuiltLinux/linux/issues/1742
Fixes: 0c3e806e ("x86/cfi: Add boot time hash randomization")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230112224948.1479453-2-samitolvanen@google.com

The memcpy() of the data following a coreboot_table_entry couldn't
be evaluated by the compiler under CONFIG_FORTIFY_SOURCE. To make it
easier to reason about, add an explicit flexible array member to struct
coreboot_device so the entire entry can be copied at once. Additionally,
validate the sizes before copying. Avoids this run-time false positive
warning:

  memcpy: detected field-spanning write (size 168) of single field "&device->entry" at drivers/firmware/google/coreboot_table.c:103 (size 8)
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Link: https://lore.kernel.org/all/03ae2704-8c30-f9f0-215b-7cdf4ad35a9a@molgen.mpg.de/
Cc: Jack Rosenthal <jrosenth@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20230107031406.gonna.761-kees@kernel.orgReviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Link: https://lore.kernel.org/r/20230112230312.give.446-kees@kernel.org

kallsyms_on_each* may schedule so must not be called with interrupts
disabled. The iteration function could disable interrupts, but this
also changes lookup_symbol() to match the change to the other timing
code.
Reported-by: Erhard F. <erhard_f@mailbox.org>
Link: https://lore.kernel.org/all/bug-216902-206035@https.bugzilla.kernel.org%2F/Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202212251728.8d0872ff-oliver.sang@intel.com
Fixes: 30f3bb09 ("kallsyms: Add self-test facility")
Tested-by: "Erhard F." <erhard_f@mailbox.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

This driver uses MSR functions that aren't implemented under UML.
Avoid building it to prevent tripping up allyesconfig.

e.g.
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x3a3): undefined reference to `__tracepoint_read_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x3d2): undefined reference to `__tracepoint_write_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x457): undefined reference to `__tracepoint_write_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x481): undefined reference to `do_trace_write_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x4d5): undefined reference to `do_trace_write_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x4f5): undefined reference to `do_trace_read_msr'
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: pata_cs5535.c:(.text+0x51c): undefined reference to `do_trace_write_msr'
Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

Pull kvm fixes from Paolo Bonzini:
 "ARM:

   - Fix the PMCR_EL0 reset value after the PMU rework

   - Correctly handle S2 fault triggered by a S1 page table walk by not
     always classifying it as a write, as this breaks on R/O memslots

   - Document why we cannot exit with KVM_EXIT_MMIO when taking a write
     fault from a S1 PTW on a R/O memslot

   - Put the Apple M2 on the naughty list for not being able to
     correctly implement the vgic SEIS feature, just like the M1 before
     it

   - Reviewer updates: Alex is stepping down, replaced by Zenghui

  x86:

   - Fix various rare locking issues in Xen emulation and teach lockdep
     to detect them

   - Documentation improvements

   - Do not return host topology information from KVM_GET_SUPPORTED_CPUID"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86/xen: Avoid deadlock by adding kvm->arch.xen.xen_lock leaf node lock
  KVM: Ensure lockdep knows about kvm->lock vs. vcpu->mutex ordering rule
  KVM: x86/xen: Fix potential deadlock in kvm_xen_update_runstate_guest()
  KVM: x86/xen: Fix lockdep warning on "recursive" gpc locking
  Documentation: kvm: fix SRCU locking order docs
  KVM: x86: Do not return host topology information from KVM_GET_SUPPORTED_CPUID
  KVM: nSVM: clarify recalc_intercepts() wrt CR8
  MAINTAINERS: Remove myself as a KVM/arm64 reviewer
  MAINTAINERS: Add Zenghui Yu as a KVM/arm64 reviewer
  KVM: arm64: vgic: Add Apple M2 cpus to the list of broken SEIS implementations
  KVM: arm64: Convert FSC_* over to ESR_ELx_FSC_*
  KVM: arm64: Document the behaviour of S1PTW faults on RO memslots
  KVM: arm64: Fix S1PTW handling on RO memslots
  KVM: arm64: PMU: Fix PMCR_EL0 reset value

On the x86-64 architecture even a failing cmpxchg grants exclusive
access to the cacheline, making it preferable to retry the failed op
immediately instead of stalling with the pause instruction.

To illustrate the impact, below are benchmark results obtained by
running various will-it-scale tests on top of the 6.2-rc3 kernel and
Cascade Lake (2 sockets * 24 cores * 2 threads) CPU.

All results in ops/s.  Note there is some variance in re-runs, but the
code is consistently faster when contention is present.

  open3 ("Same file open/close"):
  proc          stock       no-pause
     1         805603         814942       (+%1)
     2        1054980        1054781       (-0%)
     8        1544802        1822858      (+18%)
    24        1191064        2199665      (+84%)
    48         851582        1469860      (+72%)
    96         609481        1427170     (+134%)

  fstat2 ("Same file fstat"):
  proc          stock       no-pause
     1        3013872        3047636       (+1%)
     2        4284687        4400421       (+2%)
     8        3257721        5530156      (+69%)
    24        2239819        5466127     (+144%)
    48        1701072        5256609     (+209%)
    96        1269157        6649326     (+423%)

Additionally, a kernel with a private patch to help access() scalability:
access2 ("Same file access"):

  proc          stock        patched      patched
                                         +nopause
    24        2378041        2005501      5370335  (-15% / +125%)

That is, fixing the problems in access itself *reduces* scalability
after the cacheline ping-pong only happens in lockref with the pause
instruction.

Note that fstat and access benchmarks are not currently integrated into
will-it-scale, but interested parties can find them in pull requests to
said project.

Code at hand has a rather tortured history.  First modification showed
up in commit d472d9d9 ("lockref: Relax in cmpxchg loop"), written
with Itanium in mind.  Later it got patched up to use an arch-dependent
macro to stop doing it on s390 where it caused a significant regression.
Said macro had undergone revisions and was ultimately eliminated later,
going back to cpu_relax.

While I intended to only remove cpu_relax for x86-64, I got the
following comment from Linus:

    I would actually prefer just removing it entirely and see if
    somebody else hollers. You have the numbers to prove it hurts on
    real hardware, and I don't think we have any numbers to the
    contrary.

    So I think it's better to trust the numbers and remove it as a
    failure, than say "let's just remove it on x86-64 and leave
    everybody else with the potentially broken code"

Additionally, Will Deacon (maintainer of the arm64 port, one of the
architectures previously benchmarked):

    So, from the arm64 side of the fence, I'm perfectly happy just
    removing the cpu_relax() calls from lockref.

As such, come back full circle in history and whack it altogether.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/all/CAGudoHHx0Nqg6DE70zAVA75eV-HXfWyhVMWZ-aSeOofkA_=WdA@mail.gmail.com/
Acked-by: Tony Luck <tony.luck@intel.com> # ia64
Acked-by: Nicholas Piggin <npiggin@gmail.com> # powerpc
Acked-by: Will Deacon <will@kernel.org> # arm64
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Normally we reject ECAM space unless it is reported as reserved in the E820
table or via a PNP0C02 _CRS method (PCI Firmware, r3.3, sec 4.1.2).

07eab090 ("efi/x86: Remove EfiMemoryMappedIO from E820 map"), removes
E820 entries that correspond to EfiMemoryMappedIO regions because some
other firmware uses EfiMemoryMappedIO for PCI host bridge windows, and the
E820 entries prevent Linux from allocating BAR space for hot-added devices.

Some firmware doesn't report ECAM space via PNP0C02 _CRS methods, but does
mention it as an EfiMemoryMappedIO region via EFI GetMemoryMap(), which is
normally converted to an E820 entry by a bootloader or EFI stub.  After
07eab090, that E820 entry is removed, so we reject this ECAM space,
which makes PCI extended config space (offsets 0x100-0xfff) inaccessible.

The lack of extended config space breaks anything that relies on it,
including perf, VSEC telemetry, EDAC, QAT, SR-IOV, etc.

Allow use of ECAM for extended config space when the region is covered by
an EfiMemoryMappedIO region, even if it's not included in E820 or PNP0C02
_CRS.

Link: https://lore.kernel.org/r/ac2693d8-8ba3-72e0-5b66-b3ae008d539d@linux.intel.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216891
Fixes: 07eab090 ("efi/x86: Remove EfiMemoryMappedIO from E820 map")
Link: https://lore.kernel.org/r/20230110180243.1590045-3-helgaas@kernel.orgReported-by: Kan Liang <kan.liang@linux.intel.com>
Reported-by: Tony Luck <tony.luck@intel.com>
Reported-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reported-by: Yunying Sun <yunying.sun@intel.com>
Reported-by: Baowen Zheng <baowen.zheng@corigine.com>
Reported-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reported-by: Yang Lixiao <lixiao.yang@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Tested-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Tested-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Yunying Sun <yunying.sun@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>