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Commit 7643e9b9 authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar
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i386: convert hardware exception 7 to an interrupt gate 



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: default avatarAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 12394cf5

arch/x86/kernel/entry_32.S

+2 −13
Original line number Diff line number Diff line
@@ -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)

arch/x86/kernel/traps_32.c

+13 −1
Original line number Diff line number Diff line
@@ -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);