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Commit be242261 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Jiri Kosina
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s390/module: Use s390_kernel_write() for late relocations 

Because of late module patching, a livepatch module needs to be able to
apply some of its relocations well after it has been loaded.  Instead of
playing games with module_{dis,en}able_ro(), use existing text poking
mechanisms to apply relocations after module loading.

So far only x86, s390 and Power have HAVE_LIVEPATCH but only the first
two also have STRICT_MODULE_RWX.

This will allow removal of the last module_disable_ro() usage in
livepatch.  The ultimate goal is to completely disallow making
executable mappings writable.

[ jpoimboe: Split up patches.  Use mod state to determine whether
	    memcpy() can be used.  Test and add fixes. ]

Cc: linux-s390@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Suggested-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> # s390
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent cb2cceae
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Showing with 88 additions and 59 deletions
arch/s390/kernel/module.c
View file @ be242261
...@@ -19,6 +19,7 @@ ...@@ -19,6 +19,7 @@
#include <linux/kasan.h> #include <linux/kasan.h>
#include <linux/moduleloader.h> #include <linux/moduleloader.h>
#include <linux/bug.h> #include <linux/bug.h>
#include <linux/memory.h>
#include <asm/alternative.h> #include <asm/alternative.h>
#include <asm/nospec-branch.h> #include <asm/nospec-branch.h>
#include <asm/facility.h> #include <asm/facility.h>
...@@ -174,10 +175,12 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, ...@@ -174,10 +175,12 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
} }
static int apply_rela_bits(Elf_Addr loc, Elf_Addr val, static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
int sign, int bits, int shift) int sign, int bits, int shift,
void *(*write)(void *dest, const void *src, size_t len))
{ {
unsigned long umax; unsigned long umax;
long min, max; long min, max;
void *dest = (void *)loc;
if (val & ((1UL << shift) - 1)) if (val & ((1UL << shift) - 1))
return -ENOEXEC; return -ENOEXEC;
...@@ -194,26 +197,33 @@ static int apply_rela_bits(Elf_Addr loc, Elf_Addr val, ...@@ -194,26 +197,33 @@ static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
return -ENOEXEC; return -ENOEXEC;
} }
if (bits == 8) if (bits == 8) {
*(unsigned char *) loc = val; unsigned char tmp = val;
else if (bits == 12) write(dest, &tmp, 1);
*(unsigned short *) loc = (val & 0xfff) | } else if (bits == 12) {
unsigned short tmp = (val & 0xfff) |
(*(unsigned short *) loc & 0xf000); (*(unsigned short *) loc & 0xf000);
else if (bits == 16) write(dest, &tmp, 2);
*(unsigned short *) loc = val; } else if (bits == 16) {
else if (bits == 20) unsigned short tmp = val;
*(unsigned int *) loc = (val & 0xfff) << 16 | write(dest, &tmp, 2);
(val & 0xff000) >> 4 | } else if (bits == 20) {
(*(unsigned int *) loc & 0xf00000ff); unsigned int tmp = (val & 0xfff) << 16 |
else if (bits == 32) (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
*(unsigned int *) loc = val; write(dest, &tmp, 4);
else if (bits == 64) } else if (bits == 32) {
*(unsigned long *) loc = val; unsigned int tmp = val;
write(dest, &tmp, 4);
} else if (bits == 64) {
unsigned long tmp = val;
write(dest, &tmp, 8);
}
return 0; return 0;
} }
static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
const char *strtab, struct module *me) const char *strtab, struct module *me,
void *(*write)(void *dest, const void *src, size_t len))
{ {
struct mod_arch_syminfo *info; struct mod_arch_syminfo *info;
Elf_Addr loc, val; Elf_Addr loc, val;
...@@ -241,17 +251,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -241,17 +251,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_64: /* Direct 64 bit. */ case R_390_64: /* Direct 64 bit. */
val += rela->r_addend; val += rela->r_addend;
if (r_type == R_390_8) if (r_type == R_390_8)
rc = apply_rela_bits(loc, val, 0, 8, 0); rc = apply_rela_bits(loc, val, 0, 8, 0, write);
else if (r_type == R_390_12) else if (r_type == R_390_12)
rc = apply_rela_bits(loc, val, 0, 12, 0); rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_16) else if (r_type == R_390_16)
rc = apply_rela_bits(loc, val, 0, 16, 0); rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_20) else if (r_type == R_390_20)
rc = apply_rela_bits(loc, val, 1, 20, 0); rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_32) else if (r_type == R_390_32)
rc = apply_rela_bits(loc, val, 0, 32, 0); rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_64) else if (r_type == R_390_64)
rc = apply_rela_bits(loc, val, 0, 64, 0); rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break; break;
case R_390_PC16: /* PC relative 16 bit. */ case R_390_PC16: /* PC relative 16 bit. */
case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */ case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
...@@ -260,15 +270,15 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -260,15 +270,15 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_PC64: /* PC relative 64 bit. */ case R_390_PC64: /* PC relative 64 bit. */
val += rela->r_addend - loc; val += rela->r_addend - loc;
if (r_type == R_390_PC16) if (r_type == R_390_PC16)
rc = apply_rela_bits(loc, val, 1, 16, 0); rc = apply_rela_bits(loc, val, 1, 16, 0, write);
else if (r_type == R_390_PC16DBL) else if (r_type == R_390_PC16DBL)
rc = apply_rela_bits(loc, val, 1, 16, 1); rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PC32DBL) else if (r_type == R_390_PC32DBL)
rc = apply_rela_bits(loc, val, 1, 32, 1); rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PC32) else if (r_type == R_390_PC32)
rc = apply_rela_bits(loc, val, 1, 32, 0); rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_PC64) else if (r_type == R_390_PC64)
rc = apply_rela_bits(loc, val, 1, 64, 0); rc = apply_rela_bits(loc, val, 1, 64, 0, write);
break; break;
case R_390_GOT12: /* 12 bit GOT offset. */ case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */ case R_390_GOT16: /* 16 bit GOT offset. */
...@@ -283,33 +293,33 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -283,33 +293,33 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_GOTPLT64: /* 64 bit offset to jump slot. */ case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */ case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
if (info->got_initialized == 0) { if (info->got_initialized == 0) {
Elf_Addr *gotent; Elf_Addr *gotent = me->core_layout.base +
me->arch.got_offset +
info->got_offset;
gotent = me->core_layout.base + me->arch.got_offset + write(gotent, &val, sizeof(*gotent));
info->got_offset;
*gotent = val;
info->got_initialized = 1; info->got_initialized = 1;
} }
val = info->got_offset + rela->r_addend; val = info->got_offset + rela->r_addend;
if (r_type == R_390_GOT12 || if (r_type == R_390_GOT12 ||
r_type == R_390_GOTPLT12) r_type == R_390_GOTPLT12)
rc = apply_rela_bits(loc, val, 0, 12, 0); rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_GOT16 || else if (r_type == R_390_GOT16 ||
r_type == R_390_GOTPLT16) r_type == R_390_GOTPLT16)
rc = apply_rela_bits(loc, val, 0, 16, 0); rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOT20 || else if (r_type == R_390_GOT20 ||
r_type == R_390_GOTPLT20) r_type == R_390_GOTPLT20)
rc = apply_rela_bits(loc, val, 1, 20, 0); rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_GOT32 || else if (r_type == R_390_GOT32 ||
r_type == R_390_GOTPLT32) r_type == R_390_GOTPLT32)
rc = apply_rela_bits(loc, val, 0, 32, 0); rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOT64 || else if (r_type == R_390_GOT64 ||
r_type == R_390_GOTPLT64) r_type == R_390_GOTPLT64)
rc = apply_rela_bits(loc, val, 0, 64, 0); rc = apply_rela_bits(loc, val, 0, 64, 0, write);
else if (r_type == R_390_GOTENT || else if (r_type == R_390_GOTENT ||
r_type == R_390_GOTPLTENT) { r_type == R_390_GOTPLTENT) {
val += (Elf_Addr) me->core_layout.base - loc; val += (Elf_Addr) me->core_layout.base - loc;
rc = apply_rela_bits(loc, val, 1, 32, 1); rc = apply_rela_bits(loc, val, 1, 32, 1, write);
} }
break; break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */ case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
...@@ -320,25 +330,29 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -320,25 +330,29 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */ case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */ case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_initialized == 0) { if (info->plt_initialized == 0) {
unsigned int *ip; unsigned int insn[5];
ip = me->core_layout.base + me->arch.plt_offset + unsigned int *ip = me->core_layout.base +
info->plt_offset; me->arch.plt_offset +
ip[0] = 0x0d10e310; /* basr 1,0 */ info->plt_offset;
ip[1] = 0x100a0004; /* lg 1,10(1) */
insn[0] = 0x0d10e310; /* basr 1,0 */
insn[1] = 0x100a0004; /* lg 1,10(1) */
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) { if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
unsigned int *ij; unsigned int *ij;
ij = me->core_layout.base + ij = me->core_layout.base +
me->arch.plt_offset + me->arch.plt_offset +
me->arch.plt_size - PLT_ENTRY_SIZE; me->arch.plt_size - PLT_ENTRY_SIZE;
ip[2] = 0xa7f40000 + /* j __jump_r1 */ insn[2] = 0xa7f40000 + /* j __jump_r1 */
(unsigned int)(u16) (unsigned int)(u16)
(((unsigned long) ij - 8 - (((unsigned long) ij - 8 -
(unsigned long) ip) / 2); (unsigned long) ip) / 2);
} else { } else {
ip[2] = 0x07f10000; /* br %r1 */ insn[2] = 0x07f10000; /* br %r1 */
} }
ip[3] = (unsigned int) (val >> 32); insn[3] = (unsigned int) (val >> 32);
ip[4] = (unsigned int) val; insn[4] = (unsigned int) val;
write(ip, insn, sizeof(insn));
info->plt_initialized = 1; info->plt_initialized = 1;
} }
if (r_type == R_390_PLTOFF16 || if (r_type == R_390_PLTOFF16 ||
...@@ -357,17 +371,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -357,17 +371,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
val += rela->r_addend - loc; val += rela->r_addend - loc;
} }
if (r_type == R_390_PLT16DBL) if (r_type == R_390_PLT16DBL)
rc = apply_rela_bits(loc, val, 1, 16, 1); rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PLTOFF16) else if (r_type == R_390_PLTOFF16)
rc = apply_rela_bits(loc, val, 0, 16, 0); rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_PLT32DBL) else if (r_type == R_390_PLT32DBL)
rc = apply_rela_bits(loc, val, 1, 32, 1); rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PLT32 || else if (r_type == R_390_PLT32 ||
r_type == R_390_PLTOFF32) r_type == R_390_PLTOFF32)
rc = apply_rela_bits(loc, val, 0, 32, 0); rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_PLT64 || else if (r_type == R_390_PLT64 ||
r_type == R_390_PLTOFF64) r_type == R_390_PLTOFF64)
rc = apply_rela_bits(loc, val, 0, 64, 0); rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break; break;
case R_390_GOTOFF16: /* 16 bit offset to GOT. */ case R_390_GOTOFF16: /* 16 bit offset to GOT. */
case R_390_GOTOFF32: /* 32 bit offset to GOT. */ case R_390_GOTOFF32: /* 32 bit offset to GOT. */
...@@ -375,20 +389,20 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -375,20 +389,20 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
val = val + rela->r_addend - val = val + rela->r_addend -
((Elf_Addr) me->core_layout.base + me->arch.got_offset); ((Elf_Addr) me->core_layout.base + me->arch.got_offset);
if (r_type == R_390_GOTOFF16) if (r_type == R_390_GOTOFF16)
rc = apply_rela_bits(loc, val, 0, 16, 0); rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOTOFF32) else if (r_type == R_390_GOTOFF32)
rc = apply_rela_bits(loc, val, 0, 32, 0); rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOTOFF64) else if (r_type == R_390_GOTOFF64)
rc = apply_rela_bits(loc, val, 0, 64, 0); rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break; break;
case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */ case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */ case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
val = (Elf_Addr) me->core_layout.base + me->arch.got_offset + val = (Elf_Addr) me->core_layout.base + me->arch.got_offset +
rela->r_addend - loc; rela->r_addend - loc;
if (r_type == R_390_GOTPC) if (r_type == R_390_GOTPC)
rc = apply_rela_bits(loc, val, 1, 32, 0); rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_GOTPCDBL) else if (r_type == R_390_GOTPCDBL)
rc = apply_rela_bits(loc, val, 1, 32, 1); rc = apply_rela_bits(loc, val, 1, 32, 1, write);
break; break;
case R_390_COPY: case R_390_COPY:
case R_390_GLOB_DAT: /* Create GOT entry. */ case R_390_GLOB_DAT: /* Create GOT entry. */
...@@ -412,9 +426,10 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, ...@@ -412,9 +426,10 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
return 0; return 0;
} }
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec, unsigned int symindex, unsigned int relsec,
struct module *me) struct module *me,
void *(*write)(void *dest, const void *src, size_t len))
{ {
Elf_Addr base; Elf_Addr base;
Elf_Sym *symtab; Elf_Sym *symtab;
...@@ -430,13 +445,27 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, ...@@ -430,13 +445,27 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
n = sechdrs[relsec].sh_size / sizeof(Elf_Rela); n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
for (i = 0; i < n; i++, rela++) { for (i = 0; i < n; i++, rela++) {
rc = apply_rela(rela, base, symtab, strtab, me); rc = apply_rela(rela, base, symtab, strtab, me, write);
if (rc) if (rc)
return rc; return rc;
} }
return 0; return 0;
} }
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me)
{
bool early = me->state == MODULE_STATE_UNFORMED;
void *(*write)(void *, const void *, size_t) = memcpy;
if (!early)
write = s390_kernel_write;
return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
write);
}
int module_finalize(const Elf_Ehdr *hdr, int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs, const Elf_Shdr *sechdrs,
struct module *me) struct module *me)
......
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