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commit 83ae8287c1c3009459ff29241b647ff61363b22c
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Author: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Tue Feb 15 08:18:15 2022 -0600
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x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #29127]
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Re-cherry-pick commit c627209832 for strcmp-avx2.S change which was
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omitted in intial cherry pick because at the time this bug was not
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present on release branch.
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Fixes BZ #29127.
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In the overflow fallback strncmp-avx2-rtm and wcsncmp-avx2-rtm would
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call strcmp-avx2 and wcscmp-avx2 respectively. This would have
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not checks around vzeroupper and would trigger spurious
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aborts. This commit fixes that.
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test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass on
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AVX2 machines with and without RTM.
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Co-authored-by: H.J. Lu <hjl.tools@gmail.com>
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(cherry picked from commit c6272098323153db373f2986c67786ea8c85f1cf)
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diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
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index aa91f6e48a0e1ce5..a9806daadbbfd18b 100644
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--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
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+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
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@@ -345,10 +345,10 @@ L(one_or_less):
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movq %LOCALE_REG, %rdx
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# endif
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jb L(ret_zero)
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-# ifdef USE_AS_WCSCMP
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/* 'nbe' covers the case where length is negative (large
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unsigned). */
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- jnbe __wcscmp_avx2
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+ jnbe OVERFLOW_STRCMP
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+# ifdef USE_AS_WCSCMP
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movl (%rdi), %edx
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xorl %eax, %eax
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cmpl (%rsi), %edx
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@@ -357,10 +357,6 @@ L(one_or_less):
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negl %eax
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orl $1, %eax
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# else
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- /* 'nbe' covers the case where length is negative (large
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- unsigned). */
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-
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- jnbe __strcmp_avx2
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movzbl (%rdi), %eax
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movzbl (%rsi), %ecx
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TOLOWER_gpr (%rax, %eax)
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