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Reinitialize thread0's stack base after enabling XSAVE.

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Otherwise the initial call to set_top_of_stack(), which occurs before
fpuinit() sets the correct value for cpu_max_ext_state_size, leaves the
stack base at an incorrect location.  Then, when the full area is
zeroed, we end up erroneously zeroing part of the following page.

Reviewed by:	kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D24754
This commit is contained in:
Mark Johnston 2020-05-08 14:38:48 +00:00
parent deed14f451
commit cd9c23b5eb
1 changed files with 7 additions and 6 deletions
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13
sys/amd64/amd64/machdep.c
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@ -1857,7 +1857,7 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
setidt(IDT_IO_INTS + 15, IDTVEC(spuriousint), SDT_SYSIGT, SEL_KPL, 0);
#endif
#else
#error "have you forgotten the isa device?";
#error "have you forgotten the isa device?"
#endif
if (late_console)
@ -1867,12 +1867,13 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
fpuinit();
/*
* Set up thread0 pcb save area after fpuinit calculated fpu save
* area size. Zero out the extended state header in fpu save
* area.
* Reinitialize thread0's stack base now that the xsave area size is
* known. Set up thread0's pcb save area after fpuinit calculated fpu
* save area size. Zero out the extended state header in fpu save area.
*/
set_top_of_stack_td(&thread0);
thread0.td_pcb->pcb_save = get_pcb_user_save_td(&thread0);
bzero(get_pcb_user_save_td(&thread0), cpu_max_ext_state_size);
bzero(thread0.td_pcb->pcb_save, cpu_max_ext_state_size);
if (use_xsave) {
xhdr = (struct xstate_hdr *)(get_pcb_user_save_td(&thread0) +
1);
@ -1882,7 +1883,7 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
rsp0 = thread0.td_md.md_stack_base;
/* Ensure the stack is aligned to 16 bytes */
rsp0 &= ~0xFul;
__pcpu[0].pc_common_tss.tss_rsp0 = rsp0;
PCPU_PTR(common_tss)->tss_rsp0 = rsp0;
amd64_bsp_pcpu_init2(rsp0);
/* transfer to user mode */