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* [glibc/release/2.33/master] x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #29127]
@ 2022-05-25 23:11 Sunil Pandey
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From: Sunil Pandey @ 2022-05-25 23:11 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=69f16619e7119e26d70c00ac8b8750ed350147a3
commit 69f16619e7119e26d70c00ac8b8750ed350147a3
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Tue Feb 15 08:18:15 2022 -0600
x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #29127]
Re-cherry-pick commit c627209832 for strcmp-avx2.S change which was
omitted in intial cherry pick because at the time this bug was not
present on release branch.
Fixes BZ #29127.
In the overflow fallback strncmp-avx2-rtm and wcsncmp-avx2-rtm would
call strcmp-avx2 and wcscmp-avx2 respectively. This would have
not checks around vzeroupper and would trigger spurious
aborts. This commit fixes that.
test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass on
AVX2 machines with and without RTM.
Co-authored-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit c6272098323153db373f2986c67786ea8c85f1cf)
Diff:
---
sysdeps/x86_64/multiarch/strcmp-avx2.S | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index aa91f6e48a..a9806daadb 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -345,10 +345,10 @@ L(one_or_less):
movq %LOCALE_REG, %rdx
# endif
jb L(ret_zero)
-# ifdef USE_AS_WCSCMP
/* 'nbe' covers the case where length is negative (large
unsigned). */
- jnbe __wcscmp_avx2
+ jnbe OVERFLOW_STRCMP
+# ifdef USE_AS_WCSCMP
movl (%rdi), %edx
xorl %eax, %eax
cmpl (%rsi), %edx
@@ -357,10 +357,6 @@ L(one_or_less):
negl %eax
orl $1, %eax
# else
- /* 'nbe' covers the case where length is negative (large
- unsigned). */
-
- jnbe __strcmp_avx2
movzbl (%rdi), %eax
movzbl (%rsi), %ecx
TOLOWER_gpr (%rax, %eax)
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2022-05-25 23:11 [glibc/release/2.33/master] x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #29127] Sunil Pandey
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