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* [glibc] elf: Fix tst-cpu-features-cpuinfo on some AMD systems (BZ #28090)
@ 2021-07-19 17:24 Adhemerval Zanella
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From: Adhemerval Zanella @ 2021-07-19 17:24 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=469761eac842663365bba3dacd4cdf15a2ae328d
commit 469761eac842663365bba3dacd4cdf15a2ae328d
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu Jul 15 08:52:44 2021 -0300
elf: Fix tst-cpu-features-cpuinfo on some AMD systems (BZ #28090)
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>
Diff:
---
manual/platform.texi | 3 +++
sysdeps/x86/bits/platform/x86.h | 1 +
sysdeps/x86/include/cpu-features.h | 3 +++
sysdeps/x86/tst-cpu-features-cpuinfo.c | 13 ++++++++++++-
4 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/manual/platform.texi b/manual/platform.texi
index 037dfc4f20..c56ba7d413 100644
--- a/manual/platform.texi
+++ b/manual/platform.texi
@@ -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.
diff --git a/sysdeps/x86/bits/platform/x86.h b/sysdeps/x86/bits/platform/x86.h
index 5509b1ad87..2b257606b2 100644
--- a/sysdeps/x86/bits/platform/x86.h
+++ b/sysdeps/x86/bits/platform/x86.h
@@ -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)
diff --git a/sysdeps/x86/include/cpu-features.h b/sysdeps/x86/include/cpu-features.h
index 59e01df543..a3f11baa7a 100644
--- a/sysdeps/x86/include/cpu-features.h
+++ b/sysdeps/x86/include/cpu-features.h
@@ -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. */
diff --git a/sysdeps/x86/tst-cpu-features-cpuinfo.c b/sysdeps/x86/tst-cpu-features-cpuinfo.c
index f457e8677b..76bf5b2653 100644
--- a/sysdeps/x86/tst-cpu-features-cpuinfo.c
+++ b/sysdeps/x86/tst-cpu-features-cpuinfo.c
@@ -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);
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2021-07-19 17:24 [glibc] elf: Fix tst-cpu-features-cpuinfo on some AMD systems (BZ #28090) Adhemerval Zanella
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