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Merge pull request #603 from jpoimboe/warn_on_once

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create-diff-object: fix WARN*_ONCE detection on newer kernels
This commit is contained in:
Jessica Yu 2016-07-15 11:07:36 -07:00 committed by GitHub
commit 649764db02
1 changed files with 15 additions and 14 deletions
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29
kpatch-build/create-diff-object.c
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@ -231,22 +231,21 @@ out:
* Warning: Hackery lies herein. It's hopefully justified by the fact that
* this issue is very common.
*
* base object:
* Example:
*
* 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:
*
* 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_*.
* 938: be 70 00 00 00 mov $0x70,%esi
* 93d: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
* 940: R_X86_64_32S .rodata.tcp_conn_request.str1.8+0x88
* 944: c6 05 00 00 00 00 01 movb $0x1,0x0(%rip) # 94b <tcp_conn_request+0x94b>
* 946: R_X86_64_PC32 .data.unlikely-0x1
* 94b: e8 00 00 00 00 callq 950 <tcp_conn_request+0x950>
* 94c: R_X86_64_PC32 warn_slowpath_null-0x4
*
* The pattern which applies to all cases:
* 1) immediate move of the line number to %esi
* 2) (optional) string section rela
* 3) (optional) __warned.xxxxx static local rela
* 4) warn_slowpath_* rela
*/
static int kpatch_warn_only_change(struct section *sec)
{
@ -300,6 +299,8 @@ static int kpatch_warn_only_change(struct section *sec)
continue;
if (rela->string)
continue;
if (!strncmp(rela->sym->name, "__warned.", 9))
continue;
if (!strncmp(rela->sym->name, "warn_slowpath_", 14)) {
found = 1;
break;