glibc/sysdeps/x86/include, branch master

x86: Disable non-temporal memset on Skylake Server

2024-07-16T09:20:18Z

The original commit enabling non-temporal memset on Skylake Server had erroneous benchmarks (actually done on ICX). Further benchmarks indicate non-temporal stores may in fact by a regression on Skylake Server. This commit may be over-cautious in some cases, but should avoid any regressions for 2.40. Tested using qemu on all x86_64 cpu arch supported by both qemu + GLIBC. Reviewed-by: DJ Delorie Reviewed-by: H.J. Lu

x86: Add seperate non-temporal tunable for memset

2024-05-30T17:36:09Z

The tuning for non-temporal stores for memset vs memcpy is not always the same. This includes both the exact value and whether non-temporal stores are profitable at all for a given arch. This patch add `x86_memset_non_temporal_threshold`. Currently we disable non-temporal stores for non Intel vendors as the only benchmarks showing its benefit have been on Intel hardware. Reviewed-by: H.J. Lu

x86-64: Update _dl_tlsdesc_dynamic to preserve AMX registers

2024-02-29T12:30:01Z

_dl_tlsdesc_dynamic should also preserve AMX registers which are caller-saved. Add X86_XSTATE_TILECFG_ID and X86_XSTATE_TILEDATA_ID to x86-64 TLSDESC_CALL_STATE_SAVE_MASK. Compute the AMX state size and save it in xsave_state_full_size which is only used by _dl_tlsdesc_dynamic_xsave and _dl_tlsdesc_dynamic_xsavec. This fixes the AMX part of BZ #31372. Tested on AMX processor. AMX test is enabled only for compilers with the fix for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114098 GCC 14 and GCC 11/12/13 branches have the bug fix. Reviewed-by: Sunil K Pandey

Update copyright dates with scripts/update-copyrights

2024-01-01T18:53:40Z

x86/cet: Enable shadow stack during startup

2024-01-01T13:22:48Z

Previously, CET was enabled by kernel before passing control to user space and the startup code must disable CET if applications or shared libraries aren't CET enabled. Since the current kernel only supports shadow stack and won't enable shadow stack before passing control to user space, we need to enable shadow stack during startup if the application and all shared library are shadow stack enabled. There is no need to disable shadow stack at startup. Shadow stack can only be enabled in a function which will never return. Otherwise, shadow stack will underflow at the function return. 1. GL(dl_x86_feature_1) is set to the CET features which are supported by the processor and are not disabled by the tunable. Only non-zero features in GL(dl_x86_feature_1) should be enabled. After enabling shadow stack with ARCH_SHSTK_ENABLE, ARCH_SHSTK_STATUS is used to check if shadow stack is really enabled. 2. Use ARCH_SHSTK_ENABLE in RTLD_START in dynamic executable. It is safe since RTLD_START never returns. 3. Call arch_prctl (ARCH_SHSTK_ENABLE) from ARCH_SETUP_TLS in static executable. Since the start function using ARCH_SETUP_TLS never returns, it is safe to enable shadow stack in ARCH_SETUP_TLS.

x86: Add support for AVX10 preset and vec size in cpu-features

2023-09-29T19:18:42Z

This commit add support for the new AVX10 cpu features: https://cdrdv2-public.intel.com/784267/355989-intel-avx10-spec.pdf We add checks for: - `AVX10`: Check if AVX10 is present. - `AVX10_{X,Y,Z}MM`: Check if a given vec class has AVX10 support. `make check` passes and cpuid output was checked against GNR/DMR on an emulator.

: Add APX support

2023-07-27T15:42:32Z

Add support for Intel Advanced Performance Extensions: https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-performance-extensions-apx.html to .

x86: Make the divisor in setting `non_temporal_threshold` cpu specific

2023-06-12T16:33:39Z

Different systems prefer a different divisors. From benchmarks[1] so far the following divisors have been found: ICX : 2 SKX : 2 BWD : 8 For Intel, we are generalizing that BWD and older prefers 8 as a divisor, and SKL and newer prefers 2. This number can be further tuned as benchmarks are run. [1]: https://github.com/goldsteinn/memcpy-nt-benchmarks Reviewed-by: DJ Delorie

: Add PREFETCHI support

2023-04-05T21:46:10Z

Add PREFETCHI support to . Reviewed-by: Noah Goldstein

: Add AMX-COMPLEX support

2023-04-05T21:46:10Z

Add AMX-COMPLEX support to . Reviewed-by: Noah Goldstein