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FPU init: allocate initial state from UMA to ensure alignment

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The Intel Instruction Set Reference says this about the XSAVE instruction:

    Use of a destination operand not aligned to 64-byte boundary
    (in either 64-bit or 32-bit modes) results in a general-protection
    (#GP) exception.

This alignment happens naturally when all malloc buckets are powers
of two.  However, this change is necessary on some systems when
certain non-power-of-two (and non-multiple of 64) malloc buckets
are defined.

Reviewed by:	cem; kib; earlier version by jhb
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D25098
This commit is contained in:
vangyzen 2020-06-12 21:17:56 +00:00
parent 13341723a9
commit 754af14f97
2 changed files with 2 additions and 4 deletions
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3
sys/amd64/amd64/fpu.c
View File

@ -372,8 +372,7 @@ fpuinitstate(void *arg __unused)
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
fpu_initialstate = malloc(cpu_max_ext_state_size, M_DEVBUF,
M_WAITOK | M_ZERO);
fpu_initialstate = uma_zalloc(fpu_save_area_zone, M_WAITOK | M_ZERO);
if (use_xsave) {
max_ext_n = flsl(xsave_mask);
xsave_area_desc = malloc(max_ext_n * sizeof(struct

3
sys/i386/i386/npx.c
View File

@ -483,8 +483,7 @@ npxinitstate(void *arg __unused)
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
npx_initialstate = malloc(cpu_max_ext_state_size, M_DEVBUF,
M_WAITOK | M_ZERO);
npx_initialstate = uma_zalloc(fpu_save_area_zone, M_WAITOK | M_ZERO);
if (use_xsave) {
if (xsave_mask >> 32 != 0)
max_ext_n = fls(xsave_mask >> 32) + 32;