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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>
This commit is contained in:
Sunil K Pandey 2025-04-03 13:00:45 -07:00 committed by H.J. Lu
parent 8322e93dcd
commit 70b6488551
2 changed files with 24 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

74
sysdeps/x86/cpu-features.c
View File

@ -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);
}
}

6
sysdeps/x86/sysdep.h
View File

@ -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