- 12 Sep, 2022 40 commits
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wuchi authored
The code to parse option string "schedule/sleep/kvm" of cmdline in function profile_setup is redundant, so simplify that. Link: https://lkml.kernel.org/r/20220901003121.53597-1-wuchi.zero@gmail.comSigned-off-by:
wuchi <wuchi.zero@gmail.com> Reviewed-by:
Andrew Morton <akpm@linux-foudation.org> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Hawkins Jiawei authored
Kernel iterates over ATTR_RECORDs in mft record in ntfs_attr_find(). Because the ATTR_RECORDs are next to each other, kernel can get the next ATTR_RECORD from end address of current ATTR_RECORD, through current ATTR_RECORD length field. The problem is that during iteration, when kernel calculates the end address of current ATTR_RECORD, kernel may trigger an integer overflow bug in executing `a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))`. This may wrap, leading to a forever iteration on 32bit systems. This patch solves it by adding some checks on calculating end address of current ATTR_RECORD during iteration. Link: https://lkml.kernel.org/r/20220831160935.3409-4-yin31149@gmail.com Link: https://lore.kernel.org/all/20220827105842.GM2030@kadam/Signed-off-by:
Hawkins Jiawei <yin31149@gmail.com> Suggested-by:
Dan Carpenter <dan.carpenter@oracle.com> Cc: Anton Altaparmakov <anton@tuxera.com> Cc: chenxiaosong (A) <chenxiaosong2@huawei.com> Cc: syzkaller-bugs <syzkaller-bugs@googlegroups.com> Signed-off-by:
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Hawkins Jiawei authored
Kernel iterates over ATTR_RECORDs in mft record in ntfs_attr_find(). To ensure access on these ATTR_RECORDs are within bounds, kernel will do some checking during iteration. The problem is that during checking whether ATTR_RECORD's name is within bounds, kernel will dereferences the ATTR_RECORD name_offset field, before checking this ATTR_RECORD strcture is within bounds. This problem may result out-of-bounds read in ntfs_attr_find(), reported by Syzkaller: ================================================================== BUG: KASAN: use-after-free in ntfs_attr_find+0xc02/0xce0 fs/ntfs/attrib.c:597 Read of size 2 at addr ffff88807e352009 by task syz-executor153/3607 [...] Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 ntfs_attr_find+0xc02/0xce0 fs/ntfs/attrib.c:597 ntfs_attr_lookup+0x1056/0x2070 fs/ntfs/attrib.c:1193 ntfs_read_inode_mount+0x89a/0x2580 fs/ntfs/inode.c:1845 ntfs_fill_super+0x1799/0x9320 fs/ntfs/super.c:2854 mount_bdev+0x34d/0x410 fs/super.c:1400 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] </TASK> The buggy address belongs to the physical page: page:ffffea0001f8d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7e350 head:ffffea0001f8d400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011842140 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88807e351f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807e351f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807e352000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807e352080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807e352100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== This patch solves it by moving the ATTR_RECORD strcture's bounds checking earlier, then checking whether ATTR_RECORD's name is within bounds. What's more, this patch also add some comments to improve its maintainability. Link: https://lkml.kernel.org/r/20220831160935.3409-3-yin31149@gmail.com Link: https://lore.kernel.org/all/1636796c-c85e-7f47-e96f-e074fee3c7d3@huawei.com/ Link: https://groups.google.com/g/syzkaller-bugs/c/t_XdeKPGTR4/m/LECAuIGcBgAJSigned-off-by:chenxiaosong (A) <chenxiaosong2@huawei.com> Signed-off-by:
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Hawkins Jiawei authored
Patch series "ntfs: fix bugs about Attribute", v2. This patchset fixes three bugs relative to Attribute in record: Patch 1 adds a sanity check to ensure that, attrs_offset field in first mft record loading from disk is within bounds. Patch 2 moves the ATTR_RECORD's bounds checking earlier, to avoid dereferencing ATTR_RECORD before checking this ATTR_RECORD is within bounds. Patch 3 adds an overflow checking to avoid possible forever loop in ntfs_attr_find(). Without patch 1 and patch 2, the kernel triggersa KASAN use-after-free detection as reported by Syzkaller. Although one of patch 1 or patch 2 can fix this, we still need both of them. Because patch 1 fixes the root cause, and patch 2 not only fixes the direct cause, but also fixes the potential out-of-bounds bug. This patch (of 3): Syzkaller reported use-after-free read as follows: ================================================================== BUG: KASAN: use-after-free in ntfs_attr_find+0xc02/0xce0 fs/ntfs/attrib.c:597 Read of size 2 at addr ffff88807e352009 by task syz-executor153/3607 [...] Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 ntfs_attr_find+0xc02/0xce0 fs/ntfs/attrib.c:597 ntfs_attr_lookup+0x1056/0x2070 fs/ntfs/attrib.c:1193 ntfs_read_inode_mount+0x89a/0x2580 fs/ntfs/inode.c:1845 ntfs_fill_super+0x1799/0x9320 fs/ntfs/super.c:2854 mount_bdev+0x34d/0x410 fs/super.c:1400 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] </TASK> The buggy address belongs to the physical page: page:ffffea0001f8d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7e350 head:ffffea0001f8d400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011842140 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88807e351f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807e351f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807e352000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807e352080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807e352100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Kernel will loads $MFT/$DATA's first mft record in ntfs_read_inode_mount(). Yet the problem is that after loading, kernel doesn't check whether attrs_offset field is a valid value. To be more specific, if attrs_offset field is larger than bytes_allocated field, then it may trigger the out-of-bounds read bug(reported as use-after-free bug) in ntfs_attr_find(), when kernel tries to access the corresponding mft record's attribute. This patch solves it by adding the sanity check between attrs_offset field and bytes_allocated field, after loading the first mft record. Link: https://lkml.kernel.org/r/20220831160935.3409-1-yin31149@gmail.com Link: https://lkml.kernel.org/r/20220831160935.3409-2-yin31149@gmail.comSigned-off-by: -
wuchi authored
As my_inptr is only used in __init function unpack_to_rootfs(), mark it as __initdata to allow it be freed after boot. Link: https://lkml.kernel.org/r/20220827071116.83078-1-wuchi.zero@gmail.comSigned-off-by:
David Disseldorp <ddiss@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Martin Wilck <mwilck@suse.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by:
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Yang Yingliang authored
If register_kprobe() fails, the new attr is not added to the list yet, so it should call fei_attr_free() intstead. Link: https://lkml.kernel.org/r/20220826073337.2085798-3-yangyingliang@huawei.com Fixes: 4b1a29a7 ("error-injection: Support fault injection framework") Signed-off-by:
Yang Yingliang <yangyingliang@huawei.com> Reviewed-by:
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Yang Yingliang authored
Refactor the error handling of register_kprobe() to improve readability. No functional change. Link: https://lkml.kernel.org/r/20220826073337.2085798-2-yangyingliang@huawei.comSigned-off-by:
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Yang Yingliang authored
Use memdup_user_nul() helper instead of open-coding to simplify the code. Link: https://lkml.kernel.org/r/20220826073337.2085798-1-yangyingliang@huawei.comSigned-off-by:
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Uros Bizjak authored
Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in cpu_wait_death and cpu_report_death. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, atomic_try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. No functional change intended. Link: https://lkml.kernel.org/r/20220825145603.5811-1-ubizjak@gmail.comSigned-off-by:
Uros Bizjak <ubizjak@gmail.com> Signed-off-by:
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Uros Bizjak authored
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in task_work_add, task_work_cancel_match and task_work_run. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, atomic_try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. The patch avoids extra memory read in case cmpxchg fails. Link: https://lkml.kernel.org/r/20220823152632.4517-1-ubizjak@gmail.comSigned-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818210203.8251-1-wsa+renesas@sang-engineering.comSigned-off-by:
Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818210200.8203-1-wsa+renesas@sang-engineering.comSigned-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818210153.8095-1-wsa+renesas@sang-engineering.comSigned-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818210123.7637-4-wsa+renesas@sang-engineering.comSigned-off-by:
Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Changwei Ge <gechangwei@live.cn> Cc: Gang He <ghe@suse.com> Cc: Jun Piao <piaojun@huawei.com> Signed-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818205940.6216-1-wsa+renesas@sang-engineering.comSigned-off-by:
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Wolfram Sang authored
Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220818205936.6144-1-wsa+renesas@sang-engineering.comSigned-off-by:
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Uros Bizjak authored
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in set_mask_bits and bit_clear_unless. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. Link: https://lkml.kernel.org/r/20220822143851.3290-1-ubizjak@gmail.comSigned-off-by:
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Fabio M. De Francesco authored
kmap() is being deprecated in favor of kmap_local_page(). Two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in btree.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in btree.c. Where possible, use the suited standard helpers (memzero_page(), memcpy_page()) instead of open coding kmap_local_page() plus memset() or memcpy(). Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220821180400.8198-4-fmdefrancesco@gmail.comSigned-off-by:
Fabio M. De Francesco <fmdefrancesco@gmail.com> Suggested-by:
Ira Weiny <ira.weiny@intel.com> Reviewed-by:
Viacheslav Dubeyko <slava@dubeyko.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Chaitanya Kulkarni <kch@nvidia.com> Cc: Christian Brauner (Microsoft) <brauner@kernel.org> Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Kees Cook <keescook@chromium.org> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Fabio M. De Francesco authored
kmap() is being deprecated in favor of kmap_local_page(). Two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in bnode.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in bnode.c. Where possible, use the suited standard helpers (memzero_page(), memcpy_page()) instead of open coding kmap_local_page() plus memset() or memcpy(). Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220821180400.8198-3-fmdefrancesco@gmail.comSigned-off-by:
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Fabio M. De Francesco authored
Patch series "hfs: Replace kmap() with kmap_local_page()". kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmaps pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in fs/hfs is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in fs/hfs. Where possible, use the suited standard helpers (memzero_page(), memcpy_page()) instead of open coding kmap_local_page() plus memset() or memcpy(). Fix a bug due to a page being not unmapped if the code jumps to the "fail_page" label (1/3). Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. This patch (of 3): Several paths within hfs_btree_open() jump to the "fail_page" label where put_page() is called while the page is still mapped. Call kunmap() to unmap the page soon before put_page(). Link: https://lkml.kernel.org/r/20220821180400.8198-1-fmdefrancesco@gmail.com Link: https://lkml.kernel.org/r/20220821180400.8198-2-fmdefrancesco@gmail.comSigned-off-by:
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Fabio M. De Francesco authored
kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Since its use in kexec_core.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in kexec_core.c. Tested on a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220821182519.9483-1-fmdefrancesco@gmail.comSigned-off-by:
Baoquan He <bhe@redhat.com> Signed-off-by:
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Uros Bizjak authored
Use atomic64_try_cmpxchg instead of atomic64_cmpxchg (*ptr, old, new) == old in inode_set_max_iversion_raw, inode_maybe_inc_version and inode_query_iversion. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. The loop in inode_maybe_inc_iversion improves from: 5563: 48 89 ca mov %rcx,%rdx 5566: 48 89 c8 mov %rcx,%rax 5569: 48 83 e2 fe and $0xfffffffffffffffe,%rdx 556d: 48 83 c2 02 add $0x2,%rdx 5571: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi) 5576: 48 39 c1 cmp %rax,%rcx 5579: 0f 84 85 fc ff ff je 5204 <...> 557f: 48 89 c1 mov %rax,%rcx 5582: eb df jmp 5563 <...> to: 5563: 48 89 c2 mov %rax,%rdx 5566: 48 83 e2 fe and $0xfffffffffffffffe,%rdx 556a: 48 83 c2 02 add $0x2,%rdx 556e: f0 48 0f b1 11 lock cmpxchg %rdx,(%rcx) 5573: 0f 84 8b fc ff ff je 5204 <...> 5579: eb e8 jmp 5563 <...> Link: https://lkml.kernel.org/r/20220821193011.88208-1-ubizjak@gmail.comSigned-off-by: -
Uros Bizjak authored
Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in __get_reqs_available. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, atomic_try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. No functional change intended. Link: https://lkml.kernel.org/r/20220714164851.3055-1-ubizjak@gmail.comSigned-off-by:
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Uros Bizjak authored
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in discard_buffer. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. Note that the value from *ptr should be read using READ_ONCE to prevent the compiler from merging, refetching or reordering the read. No functional change intended. Link: https://lkml.kernel.org/r/20220714171653.12128-1-ubizjak@gmail.comSigned-off-by:
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Uros Bizjak authored
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in list_add_tail_lockless. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). No functional change intended. Link: https://lkml.kernel.org/r/20220714173255.12987-1-ubizjak@gmail.comSigned-off-by:
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Sergei Trofimovich authored
clock_gettime(CLOCK_MONOTONIC, &tp) is very precise on ia64 as it uses ITC (similar to rdtsc on x86). It's not quite a hrtimer as it is a few times slower than 1ns. Usually 2-3ns. clock_getres(CLOCK_MONOTONIC, &res) never reflected that fact and reported 0.04s precision (1/HZ value). In https://bugs.gentoo.org/596382 gstreamer's test suite failed loudly when it noticed precision discrepancy. Before the change: clock_getres(CLOCK_MONOTONIC, &res) reported 250Hz precision. After the change: clock_getres(CLOCK_MONOTONIC, &res) reports ITC (400Mhz) precision. The patch is based on matoro's fix. I added a bit of explanation why we need to special-case arch-specific clock_getres(). [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/20220820181813.2275195-1-slyich@gmail.comSigned-off-by:
Sergei Trofimovich <slyich@gmail.com> Cc: matoro <matoro_mailinglist_kernel@matoro.tk> Cc: Émeric Maschino <emeric.maschino@gmail.com> Signed-off-by:
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Minghao Chi authored
brelse() tests whether its argument is NULL and then returns immediately. Thus remove the tests which are not needed around the shown calls. Link: https://lkml.kernel.org/r/20220819081819.96347-1-chi.minghao@zte.com.cnSigned-off-by:
Minghao Chi <chi.minghao@zte.com.cn> Reported-by:
Zeal Robot <zealci@zte.com.cn> Cc: CGEL ZTE <cgel.zte@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minghao Chi <chi.minghao@zte.com.cn> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Kefeng Wang authored
Only x86 has own release_thread(), introduce a new weak release_thread() function to clean empty definitions in other ARCHs. Link: https://lkml.kernel.org/r/20220819014406.32266-1-wangkefeng.wang@huawei.comSigned-off-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Guo Ren <guoren@kernel.org> [csky] Acked-by:
Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Acked-by:
Geert Uytterhoeven <geert@linux-m68k.org> Acked-by:
Brian Cain <bcain@quicinc.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Acked-by: Stafford Horne <shorne@gmail.com> [openrisc] Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64] Acked-by: Huacai Chen <chenhuacai@kernel.org> [LoongArch] Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Chris Zankel <chris@zankel.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Guo Ren <guoren@kernel.org> [csky] Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Jonas Bonn <jonas@southpole.se> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michal Simek <monstr@monstr.eu> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Xuerui Wang <kernel@xen0n.name> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by:
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Brian Foster authored
Do one fork in vsyscall detection code and let SIGSEGV handler exit and carry information to the parent saving LOC. [adobriyan@gmail.com: redo original patch, delete unnecessary variables, minimise code changes] Link: https://lkml.kernel.org/r/YvoWzAn5dlhF75xa@localhost.localdomainSigned-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
Brian Foster <bfoster@redhat.com> Reviewed-by:
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Uros Bizjak authored
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in llist_add_batch and llist_del_first. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg. Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. No functional change intended. Link: https://lkml.kernel.org/r/20220712144917.4497-1-ubizjak@gmail.comSigned-off-by:
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Valentin Schneider authored
Attempting to get a crash dump out of a debug PREEMPT_RT kernel via an NMI panic() doesn't work. The cause of that lies in the PREEMPT_RT definition of mutex_trylock(): if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task())) return 0; This prevents an nmi_panic() from executing the main body of __crash_kexec() which does the actual kexec into the kdump kernel. The warning and return are explained by: 6ce47fd9 ("rtmutex: Warn if trylock is called from hard/softirq context") [...] The reasons for this are: 1) There is a potential deadlock in the slowpath 2) Another cpu which blocks on the rtmutex will boost the task which allegedly locked the rtmutex, but that cannot work because the hard/softirq context borrows the task context. Furthermore, grabbing the lock isn't NMI safe, so do away with kexec_mutex and replace it with an atomic variable. This is somewhat overzealous as *some* callsites could keep using a mutex (e.g. the sysfs-facing ones like crash_shrink_memory()), but this has the benefit of involving a single unified lock and preventing any future NMI-related surprises. Tested by triggering NMI panics via: $ echo 1 > /proc/sys/kernel/panic_on_unrecovered_nmi $ echo 1 > /proc/sys/kernel/unknown_nmi_panic $ echo 1 > /proc/sys/kernel/panic $ ipmitool power diag Link: https://lkml.kernel.org/r/20220630223258.4144112-3-vschneid@redhat.com Fixes: 6ce47fd9 ("rtmutex: Warn if trylock is called from hard/softirq context") Signed-off-by:
Valentin Schneider <vschneid@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Baoquan He <bhe@redhat.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Juri Lelli <jlelli@redhat.com> Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
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Valentin Schneider authored
Patch series "kexec, panic: Making crash_kexec() NMI safe", v4. This patch (of 2): Most acquistions of kexec_mutex are done via mutex_trylock() - those were a direct "translation" from: 8c5a1cf0 ("kexec: use a mutex for locking rather than xchg()") there have however been two additions since then that use mutex_lock(): crash_get_memory_size() and crash_shrink_memory(). A later commit will replace said mutex with an atomic variable, and locking operations will become atomic_cmpxchg(). Rather than having those mutex_lock() become while (atomic_cmpxchg(&lock, 0, 1)), turn them into trylocks that can return -EBUSY on acquisition failure. This does halve the printable size of the crash kernel, but that's still neighbouring 2G for 32bit kernels which should be ample enough. Link: https://lkml.kernel.org/r/20220630223258.4144112-1-vschneid@redhat.com Link: https://lkml.kernel.org/r/20220630223258.4144112-2-vschneid@redhat.comSigned-off-by:
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Neel Natu authored
An argument list like "arg=val arg2 \"" can trigger a page fault if the page pointed by 'args[0xffffffff]' is not mapped and potential memory corruption otherwise (unlikely but possible if the bogus address is mapped and contents happen to match the ascii value of the quote character). The fix is to ensure that we load 'args[i-1]' only when (i > 0). Prior to this commit the following command would trigger an unhandled page fault in the kernel: root@(none):/linus/fs/fat# insmod ./fat.ko "foo=bar \"" [ 33.870507] BUG: unable to handle page fault for address: ffff888204252608 [ 33.872180] #PF: supervisor read access in kernel mode [ 33.873414] #PF: error_code(0x0000) - not-present page [ 33.874650] PGD 4401067 P4D 4401067 PUD 0 [ 33.875321] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI [ 33.876113] CPU: 16 PID: 399 Comm: insmod Not tainted 5.19.0-dbg-DEV #4 [ 33.877193] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 [ 33.878739] RIP: 0010:next_arg+0xd1/0x110 [ 33.879399] Code: 22 75 1d 41 c6 04 01 00 41 80 f8 22 74 18 eb 35 4c 89 0e 45 31 d2 4c 89 cf 48 c7 02 00 00 00 00 41 80 f8 22 75 1f 41 8d 42 ff <41> 80 3c 01 22 75 14 41 c6 04 01 00 eb 0d 48 c7 02 00 00 00 00 41 [ 33.882338] RSP: 0018:ffffc90001253d08 EFLAGS: 00010246 [ 33.883174] RAX: 00000000ffffffff RBX: ffff888104252608 RCX: 0fc317bba1c1dd00 [ 33.884311] RDX: ffffc90001253d40 RSI: ffffc90001253d48 RDI: ffff888104252609 [ 33.885450] RBP: ffffc90001253d10 R08: 0000000000000022 R09: ffff888104252609 [ 33.886595] R10: 0000000000000000 R11: ffffffff82c7ff20 R12: 0000000000000282 [ 33.887748] R13: 00000000ffff8000 R14: 0000000000000000 R15: 0000000000007fff [ 33.888887] FS: 00007f04ec7432c0(0000) GS:ffff88813d300000(0000) knlGS:0000000000000000 [ 33.890183] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.891111] CR2: ffff888204252608 CR3: 0000000100f36005 CR4: 0000000000170ee0 [ 33.892241] Call Trace: [ 33.892641] <TASK> [ 33.892989] parse_args+0x8f/0x220 [ 33.893538] load_module+0x138b/0x15a0 [ 33.894149] ? prepare_coming_module+0x50/0x50 [ 33.894879] ? kernel_read_file_from_fd+0x5f/0x90 [ 33.895639] __se_sys_finit_module+0xce/0x130 [ 33.896342] __x64_sys_finit_module+0x1d/0x20 [ 33.897042] do_syscall_64+0x44/0xa0 [ 33.897622] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 33.898434] RIP: 0033:0x7f04ec85ef79 [ 33.899009] Code: 48 8d 3d da db 0d 00 0f 05 eb a5 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c7 9e 0d 00 f7 d8 64 89 01 48 [ 33.901912] RSP: 002b:00007fffae81bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 [ 33.903081] RAX: ffffffffffffffda RBX: 0000559c5f1d2640 RCX: 00007f04ec85ef79 [ 33.904191] RDX: 0000000000000000 RSI: 0000559c5f1d12a0 RDI: 0000000000000003 [ 33.905304] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 33.906421] R10: 0000000000000003 R11: 0000000000000246 R12: 0000559c5f1d12a0 [ 33.907526] R13: 0000000000000000 R14: 0000559c5f1d25f0 R15: 0000559c5f1d12a0 [ 33.908631] </TASK> [ 33.908986] Modules linked in: fat(+) [last unloaded: fat] [ 33.909843] CR2: ffff888204252608 [ 33.910375] ---[ end trace 0000000000000000 ]--- [ 33.911172] RIP: 0010:next_arg+0xd1/0x110 [ 33.911796] Code: 22 75 1d 41 c6 04 01 00 41 80 f8 22 74 18 eb 35 4c 89 0e 45 31 d2 4c 89 cf 48 c7 02 00 00 00 00 41 80 f8 22 75 1f 41 8d 42 ff <41> 80 3c 01 22 75 14 41 c6 04 01 00 eb 0d 48 c7 02 00 00 00 00 41 [ 33.914643] RSP: 0018:ffffc90001253d08 EFLAGS: 00010246 [ 33.915446] RAX: 00000000ffffffff RBX: ffff888104252608 RCX: 0fc317bba1c1dd00 [ 33.916544] RDX: ffffc90001253d40 RSI: ffffc90001253d48 RDI: ffff888104252609 [ 33.917636] RBP: ffffc90001253d10 R08: 0000000000000022 R09: ffff888104252609 [ 33.918727] R10: 0000000000000000 R11: ffffffff82c7ff20 R12: 0000000000000282 [ 33.919821] R13: 00000000ffff8000 R14: 0000000000000000 R15: 0000000000007fff [ 33.920908] FS: 00007f04ec7432c0(0000) GS:ffff88813d300000(0000) knlGS:0000000000000000 [ 33.922125] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.923017] CR2: ffff888204252608 CR3: 0000000100f36005 CR4: 0000000000170ee0 [ 33.924098] Kernel panic - not syncing: Fatal exception [ 33.925776] Kernel Offset: disabled [ 33.926347] Rebooting in 10 seconds.. Link: https://lkml.kernel.org/r/20220728232434.1666488-1-neelnatu@google.comSigned-off-by:
Neel Natu <neelnatu@google.com> Reviewed-by:
Eric Dumazet <edumazet@google.com> Signed-off-by:
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Ira Weiny authored
kmap() and kmap_atomic() are being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. kmap_local_page() is safe from any context and is therefore redundant with kmap_atomic() with the exception of any pagefault or preemption disable requirements. However, using kmap_atomic() for these side effects makes the code less clear. So any requirement for pagefault or preemption disable should be made explicitly. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored. Link: https://lkml.kernel.org/r/20220813220034.806698-1-ira.weiny@intel.comSigned-off-by:
Thomas Gleixner <tglx@linutronix.de> Suggested-by:
Chaitanya Kulkarni <kch@nvidia.com> Cc: Joe Perches <joe@perches.com> Signed-off-by:
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Fabio M. De Francesco authored
The use of kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). Tasks can be preempted and, when scheduled to run again, the kernel virtual addresses are restored and still valid. It is faster than kmap() in kernels with HIGHMEM enabled. Since kmap_local_page() can be safely used in compress.c, it should be called everywhere instead of kmap(). Therefore, replace kmap() with kmap_local_page() in compress.c. Where it is needed, use memzero_page() instead of open coding kmap_local_page() plus memset() to fill the pages with zeros. Delete the redundant flush_dcache_page() in the two call sites of memzero_page(). Tested with mkisofs on a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220801122709.8164-1-fmdefrancesco@gmail.comSigned-off-by:
Jan Kara <jack@suse.cz> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Pali Rohár <pali@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Arnd Bergmann authored
CONFIG_DEBUG_INFO is now implicitly selected if one picks one of the explicit options that could be DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT, DEBUG_INFO_DWARF4, DEBUG_INFO_DWARF5. This was actually not what I had in mind when I suggested making it a 'choice' statement, but it's too late to change again now, and the Kconfig logic is more sensible in the new form. Change any defconfig file that had CONFIG_DEBUG_INFO enabled but did not pick DWARF4 or DWARF5 explicitly to now pick the toolchain default. Link: https://lkml.kernel.org/r/20220811114609.2097335-1-arnd@kernel.org Fixes: f9b3cd24 ("Kconfig.debug: make DEBUG_INFO selectable from a choice") Signed-off-by:
Arnd Bergmann <arnd@arndb.de> Reviewed-by:
Kees Cook <keescook@chromium.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Yoshinori Sato <ysato@users.osdn.me> Cc: Rich Felker <dalias@libc.org> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by:
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Manfred Spraul authored
sysvipc_find_ipc() can be simplified further: - It uses a for() loop to locate the next entry in the idr. This can be replaced with idr_get_next(). - It receives two parameters (pos - which is actually an idr index and not a position, and new_pos, which is really a position). One parameter is sufficient. Link: https://lore.kernel.org/all/20210903052020.3265-3-manfred@colorfullife.com/ Link: https://lkml.kernel.org/r/20220805115733.104763-1-manfred@colorfullife.comSigned-off-by:
Manfred Spraul <manfred@colorfullife.com> Acked-by:
Davidlohr Bueso <dave@stgolabs.net> Acked-by:
Waiman Long <longman@redhat.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: <1vier1@web.de> Signed-off-by:
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Borislav Petkov authored
There are cases where the IP pointer in a Code: line in an oops doesn't point at the beginning of an instruction: Code: 0f bd c2 e9 a0 cd b5 e4 48 0f bd c2 e9 97 cd b5 e4 0f 1f 80 00 00 00 00 \ e9 8b cd b5 e4 0f 1f 00 66 0f a3 d0 e9 7f cd b5 e4 0f 1f <80> 00 00 00 \ 00 0f a3 d0 e9 70 cd b5 e4 48 0f a3 d0 e9 67 cd b5 e9 7f cd b5 e4 jmp 0xffffffffe4b5cda8 0f 1f 80 00 00 00 00 nopl 0x0(%rax) ^^ and the current way of determining the faulting instruction line doesn't work because disassembled instructions are counted from the IP byte to the end and when that thing points in the middle, the trailing bytes can be interpreted as different insns: Code starting with the faulting instruction =========================================== 0: 80 00 00 addb $0x0,(%rax) 3: 00 00 add %al,(%rax) whereas, this is part of 0f 1f 80 00 00 00 00 nopl 0x0(%rax) 5: 0f a3 d0 bt %edx,%eax ... leading to: 1d: 0f 1f 00 nopl (%rax) 20: 66 0f a3 d0 bt %dx,%ax 24:* e9 7f cd b5 e4 jmp 0xffffffffe4b5cda8 <-- trapping instruction 29: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) 30: 0f a3 d0 bt %edx,%eax which is the wrong faulting instruction. Change the way the faulting line number is determined by matching the opcode bytes from the beginning, leading to correct output: 1d: 0f 1f 00 nopl (%rax) 20: 66 0f a3 d0 bt %dx,%ax 24: e9 7f cd b5 e4 jmp 0xffffffffe4b5cda8 29:* 0f 1f 80 00 00 00 00 nopl 0x0(%rax) <-- trapping instruction 30: 0f a3 d0 bt %edx,%eax While at it, make decodecode use bash as the interpreter - that thing should be present on everything by now. It simplifies the code a lot too. Link: https://lkml.kernel.org/r/20220808085928.29840-1-bp@alien8.deSigned-off-by:Borislav Petkov <bp@suse.de> Cc: Marc Zyngier <maz@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by:
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Fabio M. De Francesco authored
kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Since its use in btree.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in btree.c. Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220809203105.26183-5-fmdefrancesco@gmail.comSigned-off-by:
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Fabio M. De Francesco authored
kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Since its use in bitmap.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in bitmap.c. Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220809203105.26183-4-fmdefrancesco@gmail.comSigned-off-by:
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