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Merge pull request #457 from jpoimboe/warn-fix

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warn detection fix
This commit is contained in:
Seth Jennings 2014-10-08 11:24:35 -05:00
commit a31a31f184
1 changed files with 23 additions and 18 deletions
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41
kpatch-build/create-diff-object.c
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@ -672,15 +672,20 @@ out:
*
* base object:
*
* 28e: be de 10 00 00 mov $0x10de,%esi
* 293: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
* 29a: e8 00 00 00 00 callq 29f <emulator_read_write_onepage+0x29f>
* be 5e 04 00 00 mov $0x45e,%esi
* 48 c7 c7 ff 5a a1 81 mov $0xffffffff81a15aff,%rdi
* e8 26 13 08 00 callq ffffffff8108d0d0 <warn_slowpath_fmt>
*
* patched object:
*
* 28e: be df 10 00 00 mov $0x10df,%esi
* 293: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
* 29a: e8 00 00 00 00 callq 29f <emulator_read_write_onepage+0x29f>
* be 5e 04 00 00 mov $0x45f,%esi
* 48 c7 c7 ff 5a a1 81 mov $0xffffffff81a15aff,%rdi
* e8 26 13 08 00 callq ffffffff8108d0d0 <warn_slowpath_fmt>
*
* The above is the most common case. The pattern which applies to all cases
* is an immediate move of the line number to %esi followed by zero or more
* relas to a string section followed by a rela to warn_slowpath_*.
*
*/
static int kpatch_warn_only_change(struct section *sec)
{
@ -724,22 +729,21 @@ static int kpatch_warn_only_change(struct section *sec)
if (insn1.opcode.value != 0xbe || insn2.opcode.value != 0xbe)
return 0;
/* verify the next instruction is mov $0x0,%rdi */
if (*(unsigned int *)(start1 + offset + length) != 0xc7c748)
return 0;
/* verify the instruction after that is callq */
if (*(unsigned int *)(start1 + offset + length + 7) != 0xe8)
return 0;
/* verify the callq's rela is for warn_slowpath_null */
/*
* Verify zero or more string relas followed by a
* warn_slowpath_* rela.
*/
found = 0;
list_for_each_entry(rela, &sec->rela->relas, list) {
if (rela->offset == offset + length + 8 &&
!strcmp(rela->sym->name, "warn_slowpath_null")) {
if (rela->offset < offset + length)
continue;
if (rela->string)
continue;
if (!strncmp(rela->sym->name, "warn_slowpath_", 14)) {
found = 1;
break;
}
return 0;
}
if (!found)
return 0;
@ -748,7 +752,8 @@ static int kpatch_warn_only_change(struct section *sec)
}
if (!warnonly)
ERROR("no instruction changes detected for changed section %s", sec->name);
ERROR("no instruction changes detected for changed section %s",
sec->name);
return 1;
}