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elf: Fix tst-cpu-features-cpuinfo on some AMD systems (BZ #28090)

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The SSBD feature is implemented in 2 different ways on AMD processors:
newer systems (Zen3) provides AMD_SSBD (function 8000_0008, EBX[24]),
while older system provides AMD_VIRT_SSBD (function 8000_0008, EBX[25]).
However for AMD_VIRT_SSBD, kernel shows both 'ssdb' and 'virt_ssdb' on
/proc/cpuinfo; while for AMD_SSBD only 'ssdb' is provided.

This now check is AMD_SSBD is set to check for 'ssbd', otherwise check
if AMD_VIRT_SSDB is set to check for 'virt_ssbd'.

Checked on x86_64-linux-gnu on a Ryzen 9 5900x.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Adhemerval Zanella 2021-07-15 08:52:44 -03:00
parent 5adb0e14a5
commit 469761eac8
4 changed files with 19 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
manual/platform.texi
View File

@ -189,6 +189,9 @@ The supported processor features are:
@item
@code{AMD_STIBP} -- Single thread indirect branch predictors (STIBP) for AMD cpus.
@item
@code{AMD_VIRT_SSBD} -- Speculative Store Bypass Disable (SSBD) for AMD cpus (older systems).
@item
@code{AMX_BF16} -- Tile computational operations on bfloat16 numbers.

1
sysdeps/x86/bits/platform/x86.h
View File

@ -282,6 +282,7 @@ enum
x86_cpu_AMD_IBRS = x86_cpu_index_80000008_ebx + 14,
x86_cpu_AMD_STIBP = x86_cpu_index_80000008_ebx + 15,
x86_cpu_AMD_SSBD = x86_cpu_index_80000008_ebx + 24,
x86_cpu_AMD_VIRT_SSBD = x86_cpu_index_80000008_ebx + 25,
x86_cpu_index_7_ecx_1_eax
= (CPUID_INDEX_7_ECX_1 * 8 * 4 * sizeof (unsigned int)

3
sysdeps/x86/include/cpu-features.h
View File

@ -293,6 +293,7 @@ enum
#define bit_cpu_AMD_IBRS (1u << 14)
#define bit_cpu_AMD_STIBP (1u << 15)
#define bit_cpu_AMD_SSBD (1u << 24)
#define bit_cpu_AMD_VIRT_SSBD (1u << 25)
/* CPUID_INDEX_7_ECX_1. */
@ -527,6 +528,7 @@ enum
#define index_cpu_AMD_IBRS CPUID_INDEX_80000008
#define index_cpu_AMD_STIBP CPUID_INDEX_80000008
#define index_cpu_AMD_SSBD CPUID_INDEX_80000008
#define index_cpu_AMD_VIRT_SSBD CPUID_INDEX_80000008
/* CPUID_INDEX_7_ECX_1. */
@ -761,6 +763,7 @@ enum
#define reg_AMD_IBRS ebx
#define reg_AMD_STIBP ebx
#define reg_AMD_SSBD ebx
#define reg_AMD_VIRT_SSBD ebx
/* CPUID_INDEX_7_ECX_1. */

13
sysdeps/x86/tst-cpu-features-cpuinfo.c
View File

@ -236,7 +236,18 @@ do_test (int argc, char **argv)
if (cpu_features->basic.kind == arch_kind_intel)
fails += CHECK_PROC (ssbd, SSBD);
else if (cpu_features->basic.kind == arch_kind_amd)
fails += CHECK_PROC (ssbd, AMD_SSBD);
{
/* This feature is implemented in 2 different ways on AMD processors:
newer systems provides AMD_SSBD (function 8000_0008, EBX[24]),
while older system proviseds AMD_VIRT_SSBD (function 8000_008,
EBX[25]). However for AMD_VIRT_SSBD, kernel shows both 'ssbd'
and 'virt_ssbd' on /proc/cpuinfo; while for AMD_SSBD only 'ssbd'
is provided. */
if (HAS_CPU_FEATURE (AMD_SSBD))
fails += CHECK_PROC (ssbd, AMD_SSBD);
else if (HAS_CPU_FEATURE (AMD_VIRT_SSBD))
fails += CHECK_PROC (virt_ssbd, AMD_VIRT_SSBD);
}
fails += CHECK_PROC (sse, SSE);
fails += CHECK_PROC (sse2, SSE2);
fails += CHECK_PROC (pni, SSE3);