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i386: convert hardware exception 7 to an interrupt gate

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Handle no coprocessor exception with interrupt initially off.

device_not_available in entry_32.S calls either math_state_restore
or math_emulate. This patch adds an extra indirection to be
able to re-enable interrupts explicitly in traps_32.c

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alexander van Heukelum 2008-09-09 21:56:02 +02:00 committed by Ingo Molnar
parent 12394cf567
commit 7643e9b936
2 changed files with 15 additions and 14 deletions
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15
arch/x86/kernel/entry_32.S
View File

@ -760,20 +760,9 @@ ENTRY(device_not_available)
RING0_INT_FRAME
pushl $-1 # mark this as an int
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_CR0_INTO_EAX
testl $0x4, %eax # EM (math emulation bit)
jne device_not_available_emulate
preempt_stop(CLBR_ANY)
call math_state_restore
jmp ret_from_exception
device_not_available_emulate:
pushl $0 # temporary storage for ORIG_EIP
pushl $do_device_not_available
CFI_ADJUST_CFA_OFFSET 4
call math_emulate
addl $4, %esp
CFI_ADJUST_CFA_OFFSET -4
jmp ret_from_exception
jmp error_code
CFI_ENDPROC
END(device_not_available)

14
arch/x86/kernel/traps_32.c
View File

@ -46,6 +46,7 @@
#include <linux/edac.h>
#endif
#include <asm/processor-flags.h>
#include <asm/arch_hooks.h>
#include <asm/stacktrace.h>
#include <asm/processor.h>
@ -1236,6 +1237,17 @@ asmlinkage void math_emulate(long arg)
#endif /* CONFIG_MATH_EMULATION */
void __kprobes do_device_not_available(struct pt_regs *regs, long error)
{
if (read_cr0() & X86_CR0_EM) {
conditional_sti(regs);
math_emulate(0);
} else {
math_state_restore(); /* interrupts still off */
conditional_sti(regs);
}
}
void __init trap_init(void)
{
int i;
@ -1255,7 +1267,7 @@ void __init trap_init(void)
set_system_intr_gate(4, &overflow); /* int4 can be called from all */
set_intr_gate(5, &bounds);
set_intr_gate(6, &invalid_op);
set_trap_gate(7, &device_not_available);
set_intr_gate(7, &device_not_available);
set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
set_trap_gate(9, &coprocessor_segment_overrun);
set_trap_gate(10, &invalid_TSS);