diff options
Diffstat (limited to 'arch/x86/include/asm/irqflags.h')
| -rw-r--r-- | arch/x86/include/asm/irqflags.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h index 5745ce8bf10..fdf897373e1 100644 --- a/arch/x86/include/asm/irqflags.h +++ b/arch/x86/include/asm/irqflags.h @@ -56,6 +56,61 @@ static inline void native_halt(void) #endif +#ifdef CONFIG_X86_64 +/* + * Only returns from a trap or exception to a NMI context (intra-privilege + * level near return) to the same SS and CS segments. Should be used + * upon trap or exception return when nested over a NMI context so no iret is + * issued. It takes care of modifying the eflags, rsp and returning to the + * previous function. + * + * The stack, at that point, looks like : + * + * 0(rsp) RIP + * 8(rsp) CS + * 16(rsp) EFLAGS + * 24(rsp) RSP + * 32(rsp) SS + * + * Upon execution : + * Copy EIP to the top of the return stack + * Update top of return stack address + * Pop eflags into the eflags register + * Make the return stack current + * Near return (popping the return address from the return stack) + */ +#define NATIVE_INTERRUPT_RETURN_NMI_SAFE pushq %rax; \ + movq %rsp, %rax; \ + movq 24+8(%rax), %rsp; \ + pushq 0+8(%rax); \ + pushq 16+8(%rax); \ + movq (%rax), %rax; \ + popfq; \ + ret +#else +/* + * Protected mode only, no V8086. Implies that protected mode must + * be entered before NMIs or MCEs are enabled. Only returns from a trap or + * exception to a NMI context (intra-privilege level far return). Should be used + * upon trap or exception return when nested over a NMI context so no iret is + * issued. + * + * The stack, at that point, looks like : + * + * 0(esp) EIP + * 4(esp) CS + * 8(esp) EFLAGS + * + * Upon execution : + * Copy the stack eflags to top of stack + * Pop eflags into the eflags register + * Far return: pop EIP and CS into their register, and additionally pop EFLAGS. + */ +#define NATIVE_INTERRUPT_RETURN_NMI_SAFE pushl 8(%esp); \ + popfl; \ + lret $4 +#endif + #ifdef CONFIG_PARAVIRT #include <asm/paravirt.h> #else @@ -112,6 +167,7 @@ static inline unsigned long arch_local_irq_save(void) #define ENABLE_INTERRUPTS(x) sti #define DISABLE_INTERRUPTS(x) cli +#define INTERRUPT_RETURN_NMI_SAFE NATIVE_INTERRUPT_RETURN_NMI_SAFE #ifdef CONFIG_X86_64 #define SWAPGS swapgs |