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x86: Fix lapic_ipi_alloc() on i386

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The loop which checks to see if "dynamic" IDT entries are allocated
needs to compare with the trampoline address of the reserved ISR.
Otherwise it will never succeed.

Reported by:	Harry Schmalzbauer <freebsd@omnilan.de>
Tested by:	Harry Schmalzbauer <freebsd@omnilan.de>
Reviewed by:	kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30576
This commit is contained in:
Mark Johnston 2021-05-31 18:51:14 -04:00
parent 4a59cbc125
commit 18f55c67f7
1 changed files with 10 additions and 0 deletions
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10
sys/x86/x86/local_apic.c
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@ -2127,6 +2127,10 @@ native_lapic_ipi_vectored(u_int vector, int dest)
#endif /* SMP */
#ifdef __i386__
extern uintptr_t setidt_disp;
#endif
/*
* Since the IDT is shared by all CPUs the IPI slot update needs to be globally
* visible.
@ -2155,6 +2159,9 @@ native_lapic_ipi_alloc(inthand_t *ipifunc)
for (idx = IPI_DYN_FIRST; idx <= IPI_DYN_LAST; idx++) {
ip = &idt[idx];
func = (ip->gd_hioffset << 16) | ip->gd_looffset;
#ifdef __i386__
func -= setidt_disp;
#endif
if ((!pti && func == (uintptr_t)&IDTVEC(rsvd)) ||
(pti && func == (uintptr_t)&IDTVEC(rsvd_pti))) {
vector = idx;
@ -2178,6 +2185,9 @@ native_lapic_ipi_free(int vector)
mtx_lock_spin(&icu_lock);
ip = &idt[vector];
func = (ip->gd_hioffset << 16) | ip->gd_looffset;
#ifdef __i386__
func -= setidt_disp;
#endif
KASSERT(func != (uintptr_t)&IDTVEC(rsvd) &&
func != (uintptr_t)&IDTVEC(rsvd_pti),
("invalid idtfunc %#lx", func));