diff options
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 119 |
1 files changed, 99 insertions, 20 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 7251c4f3e99e..fea49ec345ba 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -154,7 +154,7 @@ #endif /* CONFIG_X86_32_LAZY_GS */ -.macro SAVE_ALL pt_regs_ax=%eax +.macro SAVE_ALL pt_regs_ax=%eax switch_stacks=0 cld PUSH_GS pushl %fs @@ -173,6 +173,12 @@ movl $(__KERNEL_PERCPU), %edx movl %edx, %fs SET_KERNEL_GS %edx + + /* Switch to kernel stack if necessary */ +.if \switch_stacks > 0 + SWITCH_TO_KERNEL_STACK +.endif + .endm /* @@ -269,6 +275,73 @@ .Lend_\@: #endif /* CONFIG_X86_ESPFIX32 */ .endm + + +/* + * Called with pt_regs fully populated and kernel segments loaded, + * so we can access PER_CPU and use the integer registers. + * + * We need to be very careful here with the %esp switch, because an NMI + * can happen everywhere. If the NMI handler finds itself on the + * entry-stack, it will overwrite the task-stack and everything we + * copied there. So allocate the stack-frame on the task-stack and + * switch to it before we do any copying. + */ +.macro SWITCH_TO_KERNEL_STACK + + ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV + + /* Are we on the entry stack? Bail out if not! */ + movl PER_CPU_VAR(cpu_entry_area), %ecx + addl $CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx + subl %esp, %ecx /* ecx = (end of entry_stack) - esp */ + cmpl $SIZEOF_entry_stack, %ecx + jae .Lend_\@ + + /* Load stack pointer into %esi and %edi */ + movl %esp, %esi + movl %esi, %edi + + /* Move %edi to the top of the entry stack */ + andl $(MASK_entry_stack), %edi + addl $(SIZEOF_entry_stack), %edi + + /* Load top of task-stack into %edi */ + movl TSS_entry2task_stack(%edi), %edi + + /* Bytes to copy */ + movl $PTREGS_SIZE, %ecx + +#ifdef CONFIG_VM86 + testl $X86_EFLAGS_VM, PT_EFLAGS(%esi) + jz .Lcopy_pt_regs_\@ + + /* + * Stack-frame contains 4 additional segment registers when + * coming from VM86 mode + */ + addl $(4 * 4), %ecx + +.Lcopy_pt_regs_\@: +#endif + + /* Allocate frame on task-stack */ + subl %ecx, %edi + + /* Switch to task-stack */ + movl %edi, %esp + + /* + * We are now on the task-stack and can safely copy over the + * stack-frame + */ + shrl $2, %ecx + cld + rep movsl + +.Lend_\@: +.endm + /* * %eax: prev task * %edx: next task @@ -469,7 +542,7 @@ ENTRY(entry_SYSENTER_32) pushl $__USER_CS /* pt_regs->cs */ pushl $0 /* pt_regs->ip = 0 (placeholder) */ pushl %eax /* pt_regs->orig_ax */ - SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ + SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest, stack already switched */ /* * SYSENTER doesn't filter flags, so we need to clear NT, AC @@ -580,7 +653,8 @@ ENDPROC(entry_SYSENTER_32) ENTRY(entry_INT80_32) ASM_CLAC pushl %eax /* pt_regs->orig_ax */ - SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ + + SAVE_ALL pt_regs_ax=$-ENOSYS switch_stacks=1 /* save rest */ /* * User mode is traced as though IRQs are on, and the interrupt gate @@ -677,7 +751,8 @@ END(irq_entries_start) common_interrupt: ASM_CLAC addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */ - SAVE_ALL + + SAVE_ALL switch_stacks=1 ENCODE_FRAME_POINTER TRACE_IRQS_OFF movl %esp, %eax @@ -685,16 +760,16 @@ common_interrupt: jmp ret_from_intr ENDPROC(common_interrupt) -#define BUILD_INTERRUPT3(name, nr, fn) \ -ENTRY(name) \ - ASM_CLAC; \ - pushl $~(nr); \ - SAVE_ALL; \ - ENCODE_FRAME_POINTER; \ - TRACE_IRQS_OFF \ - movl %esp, %eax; \ - call fn; \ - jmp ret_from_intr; \ +#define BUILD_INTERRUPT3(name, nr, fn) \ +ENTRY(name) \ + ASM_CLAC; \ + pushl $~(nr); \ + SAVE_ALL switch_stacks=1; \ + ENCODE_FRAME_POINTER; \ + TRACE_IRQS_OFF \ + movl %esp, %eax; \ + call fn; \ + jmp ret_from_intr; \ ENDPROC(name) #define BUILD_INTERRUPT(name, nr) \ @@ -926,16 +1001,20 @@ common_exception: pushl %es pushl %ds pushl %eax + movl $(__USER_DS), %eax + movl %eax, %ds + movl %eax, %es + movl $(__KERNEL_PERCPU), %eax + movl %eax, %fs pushl %ebp pushl %edi pushl %esi pushl %edx pushl %ecx pushl %ebx + SWITCH_TO_KERNEL_STACK ENCODE_FRAME_POINTER cld - movl $(__KERNEL_PERCPU), %ecx - movl %ecx, %fs UNWIND_ESPFIX_STACK GS_TO_REG %ecx movl PT_GS(%esp), %edi # get the function address @@ -943,9 +1022,6 @@ common_exception: movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart REG_TO_PTGS %ecx SET_KERNEL_GS %ecx - movl $(__USER_DS), %ecx - movl %ecx, %ds - movl %ecx, %es TRACE_IRQS_OFF movl %esp, %eax # pt_regs pointer CALL_NOSPEC %edi @@ -964,6 +1040,7 @@ ENTRY(debug) */ ASM_CLAC pushl $-1 # mark this as an int + SAVE_ALL ENCODE_FRAME_POINTER xorl %edx, %edx # error code 0 @@ -999,6 +1076,7 @@ END(debug) */ ENTRY(nmi) ASM_CLAC + #ifdef CONFIG_X86_ESPFIX32 pushl %eax movl %ss, %eax @@ -1066,7 +1144,8 @@ END(nmi) ENTRY(int3) ASM_CLAC pushl $-1 # mark this as an int - SAVE_ALL + + SAVE_ALL switch_stacks=1 ENCODE_FRAME_POINTER TRACE_IRQS_OFF xorl %edx, %edx # zero error code |