diff options
Diffstat (limited to 'arch/x86/entry/entry_32.S')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 145 |
1 files changed, 95 insertions, 50 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 21b352a11b49..701d29f8e4d3 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -45,6 +45,7 @@ #include <asm/asm.h> #include <asm/smap.h> #include <asm/export.h> +#include <asm/frame.h> .section .entry.text, "ax" @@ -175,6 +176,22 @@ SET_KERNEL_GS %edx .endm +/* + * This is a sneaky trick to help the unwinder find pt_regs on the stack. The + * frame pointer is replaced with an encoded pointer to pt_regs. The encoding + * is just setting the LSB, which makes it an invalid stack address and is also + * a signal to the unwinder that it's a pt_regs pointer in disguise. + * + * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the + * original rbp. + */ +.macro ENCODE_FRAME_POINTER +#ifdef CONFIG_FRAME_POINTER + mov %esp, %ebp + orl $0x1, %ebp +#endif +.endm + .macro RESTORE_INT_REGS popl %ebx popl %ecx @@ -238,6 +255,23 @@ ENTRY(__switch_to_asm) END(__switch_to_asm) /* + * The unwinder expects the last frame on the stack to always be at the same + * offset from the end of the page, which allows it to validate the stack. + * Calling schedule_tail() directly would break that convention because its an + * asmlinkage function so its argument has to be pushed on the stack. This + * wrapper creates a proper "end of stack" frame header before the call. + */ +ENTRY(schedule_tail_wrapper) + FRAME_BEGIN + + pushl %eax + call schedule_tail + popl %eax + + FRAME_END + ret +ENDPROC(schedule_tail_wrapper) +/* * A newly forked process directly context switches into this address. * * eax: prev task we switched from @@ -245,9 +279,7 @@ END(__switch_to_asm) * edi: kernel thread arg */ ENTRY(ret_from_fork) - pushl %eax - call schedule_tail - popl %eax + call schedule_tail_wrapper testl %ebx, %ebx jnz 1f /* kernel threads are uncommon */ @@ -307,13 +339,13 @@ END(ret_from_exception) #ifdef CONFIG_PREEMPT ENTRY(resume_kernel) DISABLE_INTERRUPTS(CLBR_ANY) -need_resched: +.Lneed_resched: cmpl $0, PER_CPU_VAR(__preempt_count) jnz restore_all testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ? jz restore_all call preempt_schedule_irq - jmp need_resched + jmp .Lneed_resched END(resume_kernel) #endif @@ -334,7 +366,7 @@ GLOBAL(__begin_SYSENTER_singlestep_region) */ ENTRY(xen_sysenter_target) addl $5*4, %esp /* remove xen-provided frame */ - jmp sysenter_past_esp + jmp .Lsysenter_past_esp #endif /* @@ -371,7 +403,7 @@ ENTRY(xen_sysenter_target) */ ENTRY(entry_SYSENTER_32) movl TSS_sysenter_sp0(%esp), %esp -sysenter_past_esp: +.Lsysenter_past_esp: pushl $__USER_DS /* pt_regs->ss */ pushl %ebp /* pt_regs->sp (stashed in bp) */ pushfl /* pt_regs->flags (except IF = 0) */ @@ -504,9 +536,9 @@ ENTRY(entry_INT80_32) restore_all: TRACE_IRQS_IRET -restore_all_notrace: +.Lrestore_all_notrace: #ifdef CONFIG_X86_ESPFIX32 - ALTERNATIVE "jmp restore_nocheck", "", X86_BUG_ESPFIX + ALTERNATIVE "jmp .Lrestore_nocheck", "", X86_BUG_ESPFIX movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS /* @@ -518,22 +550,23 @@ restore_all_notrace: movb PT_CS(%esp), %al andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax - je ldt_ss # returning to user-space with LDT SS + je .Lldt_ss # returning to user-space with LDT SS #endif -restore_nocheck: +.Lrestore_nocheck: RESTORE_REGS 4 # skip orig_eax/error_code -irq_return: +.Lirq_return: INTERRUPT_RETURN + .section .fixup, "ax" ENTRY(iret_exc ) pushl $0 # no error code pushl $do_iret_error - jmp error_code + jmp common_exception .previous - _ASM_EXTABLE(irq_return, iret_exc) + _ASM_EXTABLE(.Lirq_return, iret_exc) #ifdef CONFIG_X86_ESPFIX32 -ldt_ss: +.Lldt_ss: /* * Setup and switch to ESPFIX stack * @@ -562,7 +595,7 @@ ldt_ss: */ DISABLE_INTERRUPTS(CLBR_EAX) lss (%esp), %esp /* switch to espfix segment */ - jmp restore_nocheck + jmp .Lrestore_nocheck #endif ENDPROC(entry_INT80_32) @@ -624,6 +657,7 @@ common_interrupt: ASM_CLAC addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */ SAVE_ALL + ENCODE_FRAME_POINTER TRACE_IRQS_OFF movl %esp, %eax call do_IRQ @@ -635,6 +669,7 @@ ENTRY(name) \ ASM_CLAC; \ pushl $~(nr); \ SAVE_ALL; \ + ENCODE_FRAME_POINTER; \ TRACE_IRQS_OFF \ movl %esp, %eax; \ call fn; \ @@ -659,7 +694,7 @@ ENTRY(coprocessor_error) ASM_CLAC pushl $0 pushl $do_coprocessor_error - jmp error_code + jmp common_exception END(coprocessor_error) ENTRY(simd_coprocessor_error) @@ -673,14 +708,14 @@ ENTRY(simd_coprocessor_error) #else pushl $do_simd_coprocessor_error #endif - jmp error_code + jmp common_exception END(simd_coprocessor_error) ENTRY(device_not_available) ASM_CLAC pushl $-1 # mark this as an int pushl $do_device_not_available - jmp error_code + jmp common_exception END(device_not_available) #ifdef CONFIG_PARAVIRT @@ -694,59 +729,59 @@ ENTRY(overflow) ASM_CLAC pushl $0 pushl $do_overflow - jmp error_code + jmp common_exception END(overflow) ENTRY(bounds) ASM_CLAC pushl $0 pushl $do_bounds - jmp error_code + jmp common_exception END(bounds) ENTRY(invalid_op) ASM_CLAC pushl $0 pushl $do_invalid_op - jmp error_code + jmp common_exception END(invalid_op) ENTRY(coprocessor_segment_overrun) ASM_CLAC pushl $0 pushl $do_coprocessor_segment_overrun - jmp error_code + jmp common_exception END(coprocessor_segment_overrun) ENTRY(invalid_TSS) ASM_CLAC pushl $do_invalid_TSS - jmp error_code + jmp common_exception END(invalid_TSS) ENTRY(segment_not_present) ASM_CLAC pushl $do_segment_not_present - jmp error_code + jmp common_exception END(segment_not_present) ENTRY(stack_segment) ASM_CLAC pushl $do_stack_segment - jmp error_code + jmp common_exception END(stack_segment) ENTRY(alignment_check) ASM_CLAC pushl $do_alignment_check - jmp error_code + jmp common_exception END(alignment_check) ENTRY(divide_error) ASM_CLAC pushl $0 # no error code pushl $do_divide_error - jmp error_code + jmp common_exception END(divide_error) #ifdef CONFIG_X86_MCE @@ -754,7 +789,7 @@ ENTRY(machine_check) ASM_CLAC pushl $0 pushl machine_check_vector - jmp error_code + jmp common_exception END(machine_check) #endif @@ -762,13 +797,14 @@ ENTRY(spurious_interrupt_bug) ASM_CLAC pushl $0 pushl $do_spurious_interrupt_bug - jmp error_code + jmp common_exception END(spurious_interrupt_bug) #ifdef CONFIG_XEN ENTRY(xen_hypervisor_callback) pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL + ENCODE_FRAME_POINTER TRACE_IRQS_OFF /* @@ -823,6 +859,7 @@ ENTRY(xen_failsafe_callback) jmp iret_exc 5: pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL + ENCODE_FRAME_POINTER jmp ret_from_exception .section .fixup, "ax" @@ -882,15 +919,15 @@ ftrace_call: popl %edx popl %ecx popl %eax -ftrace_ret: +.Lftrace_ret: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call ftrace_graph_call: jmp ftrace_stub #endif -.globl ftrace_stub -ftrace_stub: +/* This is weak to keep gas from relaxing the jumps */ +WEAK(ftrace_stub) ret END(ftrace_caller) @@ -952,7 +989,7 @@ GLOBAL(ftrace_regs_call) popl %gs addl $8, %esp /* Skip orig_ax and ip */ popf /* Pop flags at end (no addl to corrupt flags) */ - jmp ftrace_ret + jmp .Lftrace_ret popf jmp ftrace_stub @@ -963,7 +1000,7 @@ ENTRY(mcount) jb ftrace_stub /* Paging not enabled yet? */ cmpl $ftrace_stub, ftrace_trace_function - jnz trace + jnz .Ltrace #ifdef CONFIG_FUNCTION_GRAPH_TRACER cmpl $ftrace_stub, ftrace_graph_return jnz ftrace_graph_caller @@ -976,7 +1013,7 @@ ftrace_stub: ret /* taken from glibc */ -trace: +.Ltrace: pushl %eax pushl %ecx pushl %edx @@ -1027,7 +1064,7 @@ return_to_handler: ENTRY(trace_page_fault) ASM_CLAC pushl $trace_do_page_fault - jmp error_code + jmp common_exception END(trace_page_fault) #endif @@ -1035,7 +1072,10 @@ ENTRY(page_fault) ASM_CLAC pushl $do_page_fault ALIGN -error_code: + jmp common_exception +END(page_fault) + +common_exception: /* the function address is in %gs's slot on the stack */ pushl %fs pushl %es @@ -1047,6 +1087,7 @@ error_code: pushl %edx pushl %ecx pushl %ebx + ENCODE_FRAME_POINTER cld movl $(__KERNEL_PERCPU), %ecx movl %ecx, %fs @@ -1064,7 +1105,7 @@ error_code: movl %esp, %eax # pt_regs pointer call *%edi jmp ret_from_exception -END(page_fault) +END(common_exception) ENTRY(debug) /* @@ -1079,6 +1120,7 @@ ENTRY(debug) ASM_CLAC pushl $-1 # mark this as an int SAVE_ALL + ENCODE_FRAME_POINTER xorl %edx, %edx # error code 0 movl %esp, %eax # pt_regs pointer @@ -1094,11 +1136,11 @@ ENTRY(debug) .Ldebug_from_sysenter_stack: /* We're on the SYSENTER stack. Switch off. */ - movl %esp, %ebp + movl %esp, %ebx movl PER_CPU_VAR(cpu_current_top_of_stack), %esp TRACE_IRQS_OFF call do_debug - movl %ebp, %esp + movl %ebx, %esp jmp ret_from_exception END(debug) @@ -1116,11 +1158,12 @@ ENTRY(nmi) movl %ss, %eax cmpw $__ESPFIX_SS, %ax popl %eax - je nmi_espfix_stack + je .Lnmi_espfix_stack #endif pushl %eax # pt_regs->orig_ax SAVE_ALL + ENCODE_FRAME_POINTER xorl %edx, %edx # zero error code movl %esp, %eax # pt_regs pointer @@ -1132,21 +1175,21 @@ ENTRY(nmi) /* Not on SYSENTER stack. */ call do_nmi - jmp restore_all_notrace + jmp .Lrestore_all_notrace .Lnmi_from_sysenter_stack: /* * We're on the SYSENTER stack. Switch off. No one (not even debug) * is using the thread stack right now, so it's safe for us to use it. */ - movl %esp, %ebp + movl %esp, %ebx movl PER_CPU_VAR(cpu_current_top_of_stack), %esp call do_nmi - movl %ebp, %esp - jmp restore_all_notrace + movl %ebx, %esp + jmp .Lrestore_all_notrace #ifdef CONFIG_X86_ESPFIX32 -nmi_espfix_stack: +.Lnmi_espfix_stack: /* * create the pointer to lss back */ @@ -1159,12 +1202,13 @@ nmi_espfix_stack: .endr pushl %eax SAVE_ALL + ENCODE_FRAME_POINTER FIXUP_ESPFIX_STACK # %eax == %esp xorl %edx, %edx # zero error code call do_nmi RESTORE_REGS lss 12+4(%esp), %esp # back to espfix stack - jmp irq_return + jmp .Lirq_return #endif END(nmi) @@ -1172,6 +1216,7 @@ ENTRY(int3) ASM_CLAC pushl $-1 # mark this as an int SAVE_ALL + ENCODE_FRAME_POINTER TRACE_IRQS_OFF xorl %edx, %edx # zero error code movl %esp, %eax # pt_regs pointer @@ -1181,14 +1226,14 @@ END(int3) ENTRY(general_protection) pushl $do_general_protection - jmp error_code + jmp common_exception END(general_protection) #ifdef CONFIG_KVM_GUEST ENTRY(async_page_fault) ASM_CLAC pushl $do_async_page_fault - jmp error_code + jmp common_exception END(async_page_fault) #endif |