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authorSunil K Pandey <skpgkp2@gmail.com>2025-04-03 13:00:45 -0700
committerH.J. Lu <hjl.tools@gmail.com>2025-04-05 07:51:38 -0700
commit70b648855185e967e54668b101d24704c3fb869d (patch)
tree9c6f41f6ded189ec3de35dcddb3a4aa4652294ad
parent8322e93dcdf08d38977f3e9b771c7c1f6dc74542 (diff)
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x86: Optimize xstate size calculation
Scan xstate IDs up to the maximum supported xstate ID. Remove the separate AMX xstate calculation. Instead, exclude the AMX space from the start of TILECFG to the end of TILEDATA in xsave_state_size. Completed validation on SKL/SKX/SPR/SDE and compared xsave state size with "ld.so --list-diagnostics" option, no regression. Co-Authored-By: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
-rw-r--r--sysdeps/x86/cpu-features.c74
-rw-r--r--sysdeps/x86/sysdep.h6
2 files changed, 24 insertions, 56 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 6cf7e4c..9d136e4 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -325,13 +325,8 @@ update_active (struct cpu_features *cpu_features)
/* Check if XSAVEC is available. */
if (CPU_FEATURES_CPU_P (cpu_features, XSAVEC))
{
- unsigned int xstate_comp_offsets[32];
- unsigned int xstate_comp_sizes[32];
-#ifdef __x86_64__
- unsigned int xstate_amx_comp_offsets[32];
- unsigned int xstate_amx_comp_sizes[32];
- unsigned int amx_ecx;
-#endif
+ unsigned int xstate_comp_offsets[X86_XSTATE_MAX_ID + 1];
+ unsigned int xstate_comp_sizes[X86_XSTATE_MAX_ID + 1];
unsigned int i;
xstate_comp_offsets[0] = 0;
@@ -339,39 +334,16 @@ update_active (struct cpu_features *cpu_features)
xstate_comp_offsets[2] = 576;
xstate_comp_sizes[0] = 160;
xstate_comp_sizes[1] = 256;
-#ifdef __x86_64__
- xstate_amx_comp_offsets[0] = 0;
- xstate_amx_comp_offsets[1] = 160;
- xstate_amx_comp_offsets[2] = 576;
- xstate_amx_comp_sizes[0] = 160;
- xstate_amx_comp_sizes[1] = 256;
-#endif
- for (i = 2; i < 32; i++)
+ for (i = 2; i <= X86_XSTATE_MAX_ID; i++)
{
if ((FULL_STATE_SAVE_MASK & (1 << i)) != 0)
{
__cpuid_count (0xd, i, eax, ebx, ecx, edx);
-#ifdef __x86_64__
- /* Include this in xsave_state_full_size. */
- amx_ecx = ecx;
- xstate_amx_comp_sizes[i] = eax;
- if ((AMX_STATE_SAVE_MASK & (1 << i)) != 0)
- {
- /* Exclude this from xsave_state_size. */
- ecx = 0;
- xstate_comp_sizes[i] = 0;
- }
- else
-#endif
- xstate_comp_sizes[i] = eax;
+ xstate_comp_sizes[i] = eax;
}
else
{
-#ifdef __x86_64__
- amx_ecx = 0;
- xstate_amx_comp_sizes[i] = 0;
-#endif
ecx = 0;
xstate_comp_sizes[i] = 0;
}
@@ -380,42 +352,32 @@ update_active (struct cpu_features *cpu_features)
{
xstate_comp_offsets[i]
= (xstate_comp_offsets[i - 1]
- + xstate_comp_sizes[i -1]);
+ + xstate_comp_sizes[i - 1]);
if ((ecx & (1 << 1)) != 0)
xstate_comp_offsets[i]
= ALIGN_UP (xstate_comp_offsets[i], 64);
-#ifdef __x86_64__
- xstate_amx_comp_offsets[i]
- = (xstate_amx_comp_offsets[i - 1]
- + xstate_amx_comp_sizes[i - 1]);
- if ((amx_ecx & (1 << 1)) != 0)
- xstate_amx_comp_offsets[i]
- = ALIGN_UP (xstate_amx_comp_offsets[i],
- 64);
-#endif
}
}
/* Use XSAVEC. */
unsigned int size
- = xstate_comp_offsets[31] + xstate_comp_sizes[31];
+ = (xstate_comp_offsets[X86_XSTATE_MAX_ID]
+ + xstate_comp_sizes[X86_XSTATE_MAX_ID]);
if (size)
{
+ size = ALIGN_UP (size + TLSDESC_CALL_REGISTER_SAVE_AREA,
+ 64);
#ifdef __x86_64__
- unsigned int amx_size
- = (xstate_amx_comp_offsets[31]
- + xstate_amx_comp_sizes[31]);
- amx_size
- = ALIGN_UP ((amx_size
- + TLSDESC_CALL_REGISTER_SAVE_AREA),
- 64);
- /* Set TLSDESC state size to the compact AMX
- state size for XSAVEC. */
- _dl_x86_features_tlsdesc_state_size = amx_size;
+ _dl_x86_features_tlsdesc_state_size = size;
+ /* Exclude the AMX space from the start of TILECFG
+ space to the end of TILEDATA space. If CPU
+ doesn't support AMX, TILECFG offset is the same
+ as TILEDATA + 1 offset. Otherwise, they are
+ multiples of 64. */
+ size -= (xstate_comp_offsets[X86_XSTATE_TILEDATA_ID + 1]
+ - xstate_comp_offsets[X86_XSTATE_TILECFG_ID]);
#endif
- cpu_features->xsave_state_size
- = ALIGN_UP (size + TLSDESC_CALL_REGISTER_SAVE_AREA,
- 64);
+ cpu_features->xsave_state_size = size;
CPU_FEATURE_SET (cpu_features, XSAVEC);
}
}
diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
index 541393f..c3c73e7 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -102,6 +102,9 @@
| (1 << X86_XSTATE_ZMM_ID) \
| (1 << X86_XSTATE_APX_F_ID))
+/* The maximum supported xstate ID. */
+# define X86_XSTATE_MAX_ID X86_XSTATE_APX_F_ID
+
/* AMX state mask. */
# define AMX_STATE_SAVE_MASK \
((1 << X86_XSTATE_TILECFG_ID) | (1 << X86_XSTATE_TILEDATA_ID))
@@ -123,6 +126,9 @@
| (1 << X86_XSTATE_K_ID) \
| (1 << X86_XSTATE_ZMM_H_ID))
+/* The maximum supported xstate ID. */
+# define X86_XSTATE_MAX_ID X86_XSTATE_ZMM_H_ID
+
/* States to be included in xsave_state_size. */
# define FULL_STATE_SAVE_MASK STATE_SAVE_MASK
#endif