668eaab0c7
* Fri Jul 22 2022 Arjun Shankar <arjun@redhat.com> - 2.34-40
- Sync with upstream branch release/2.34/master,
commit b2f32e746492615a6eb3e66fac1e766e32e8deb1:
- malloc: Simplify implementation of __malloc_assert
- Update syscall-names.list for Linux 5.18
- x86: Add missing IS_IN (libc) check to strncmp-sse4_2.S
- x86: Move mem{p}{mov|cpy}_{chk_}erms to its own file
- x86: Move and slightly improve memset_erms
- x86: Add definition for __wmemset_chk AVX2 RTM in ifunc impl list
- x86: Put wcs{n}len-sse4.1 in the sse4.1 text section
- x86: Align entry for memrchr to 64-bytes.
- x86: Add BMI1/BMI2 checks for ISA_V3 check
- x86: Cleanup bounds checking in large memcpy case
- x86: Add bounds `x86_non_temporal_threshold`
- x86: Add sse42 implementation to strcmp's ifunc
- x86: Fix misordered logic for setting `rep_movsb_stop_threshold`
- x86: Align varshift table to 32-bytes
- x86: ZERO_UPPER_VEC_REGISTERS_RETURN_XTEST expect no transactions
- x86: Shrink code size of memchr-evex.S
- x86: Shrink code size of memchr-avx2.S
- x86: Optimize memrchr-avx2.S
- x86: Optimize memrchr-evex.S
- x86: Optimize memrchr-sse2.S
- x86: Add COND_VZEROUPPER that can replace vzeroupper if no `ret`
- x86: Create header for VEC classes in x86 strings library
- x86_64: Add strstr function with 512-bit EVEX
- x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT
- x86_64: Implement evex512 version of strlen, strnlen, wcslen and wcsnlen
- x86_64: Remove bzero optimization
- x86_64: Remove end of line trailing spaces
- nptl: Fix ___pthread_unregister_cancel_restore asynchronous restore
- linux: Fix mq_timereceive check for 32 bit fallback code (BZ 29304)
Resolves: #2109505
91 lines
2.5 KiB
Diff
91 lines
2.5 KiB
Diff
commit e805606193e1a39956ca5ef73cb44a8796730686
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Author: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Mon Jun 6 21:11:28 2022 -0700
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x86: Add COND_VZEROUPPER that can replace vzeroupper if no `ret`
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The RTM vzeroupper mitigation has no way of replacing inline
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vzeroupper not before a return.
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This can be useful when hoisting a vzeroupper to save code size
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for example:
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```
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L(foo):
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cmpl %eax, %edx
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jz L(bar)
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tzcntl %eax, %eax
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addq %rdi, %rax
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VZEROUPPER_RETURN
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L(bar):
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xorl %eax, %eax
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VZEROUPPER_RETURN
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```
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Can become:
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```
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L(foo):
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COND_VZEROUPPER
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cmpl %eax, %edx
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jz L(bar)
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tzcntl %eax, %eax
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addq %rdi, %rax
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ret
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L(bar):
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xorl %eax, %eax
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ret
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```
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This code does not change any existing functionality.
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There is no difference in the objdump of libc.so before and after this
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patch.
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
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(cherry picked from commit dd5c483b2598f411428df4d8864c15c4b8a3cd68)
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diff --git a/sysdeps/x86_64/multiarch/avx-rtm-vecs.h b/sysdeps/x86_64/multiarch/avx-rtm-vecs.h
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index 3f531dd47fceefe9..6ca9f5e6bae7ba72 100644
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--- a/sysdeps/x86_64/multiarch/avx-rtm-vecs.h
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+++ b/sysdeps/x86_64/multiarch/avx-rtm-vecs.h
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@@ -20,6 +20,7 @@
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#ifndef _AVX_RTM_VECS_H
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#define _AVX_RTM_VECS_H 1
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+#define COND_VZEROUPPER COND_VZEROUPPER_XTEST
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#define ZERO_UPPER_VEC_REGISTERS_RETURN \
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ZERO_UPPER_VEC_REGISTERS_RETURN_XTEST
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diff --git a/sysdeps/x86_64/sysdep.h b/sysdeps/x86_64/sysdep.h
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index 7bebdeb21095eda0..93e44be22e2275f1 100644
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--- a/sysdeps/x86_64/sysdep.h
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+++ b/sysdeps/x86_64/sysdep.h
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@@ -106,6 +106,24 @@ lose: \
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vzeroupper; \
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ret
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+/* Can be used to replace vzeroupper that is not directly before a
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+ return. This is useful when hoisting a vzeroupper from multiple
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+ return paths to decrease the total number of vzerouppers and code
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+ size. */
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+#define COND_VZEROUPPER_XTEST \
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+ xtest; \
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+ jz 1f; \
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+ vzeroall; \
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+ jmp 2f; \
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+1: \
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+ vzeroupper; \
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+2:
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+
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+/* In RTM define this as COND_VZEROUPPER_XTEST. */
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+#ifndef COND_VZEROUPPER
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+# define COND_VZEROUPPER vzeroupper
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+#endif
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+
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/* Zero upper vector registers and return. */
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#ifndef ZERO_UPPER_VEC_REGISTERS_RETURN
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# define ZERO_UPPER_VEC_REGISTERS_RETURN \
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