diff options
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 40 |
1 files changed, 33 insertions, 7 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 9ee0da180..02fff3ebf 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -288,11 +288,15 @@ return_from_SYSCALL_64: jne opportunistic_sysret_failed /* - * SYSRET can't restore RF. SYSRET can restore TF, but unlike IRET, - * restoring TF results in a trap from userspace immediately after - * SYSRET. This would cause an infinite loop whenever #DB happens - * with register state that satisfies the opportunistic SYSRET - * conditions. For example, single-stepping this user code: + * SYSCALL clears RF when it saves RFLAGS in R11 and SYSRET cannot + * restore RF properly. If the slowpath sets it for whatever reason, we + * need to restore it correctly. + * + * SYSRET can restore TF, but unlike IRET, restoring TF results in a + * trap from userspace immediately after SYSRET. This would cause an + * infinite loop whenever #DB happens with register state that satisfies + * the opportunistic SYSRET conditions. For example, single-stepping + * this user code: * * movq $stuck_here, %rcx * pushfq @@ -601,9 +605,20 @@ apicinterrupt3 \num trace(\sym) smp_trace(\sym) .endm #endif +/* Make sure APIC interrupt handlers end up in the irqentry section: */ +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) +# define PUSH_SECTION_IRQENTRY .pushsection .irqentry.text, "ax" +# define POP_SECTION_IRQENTRY .popsection +#else +# define PUSH_SECTION_IRQENTRY +# define POP_SECTION_IRQENTRY +#endif + .macro apicinterrupt num sym do_sym +PUSH_SECTION_IRQENTRY apicinterrupt3 \num \sym \do_sym trace_apicinterrupt \num \sym +POP_SECTION_IRQENTRY .endm #ifdef CONFIG_SMP @@ -987,7 +1002,6 @@ ENTRY(error_entry) testb $3, CS+8(%rsp) jz .Lerror_kernelspace -.Lerror_entry_from_usermode_swapgs: /* * We entered from user mode or we're pretending to have entered * from user mode due to an IRET fault. @@ -1030,7 +1044,8 @@ ENTRY(error_entry) * gsbase and proceed. We'll fix up the exception and land in * .Lgs_change's error handler with kernel gsbase. */ - jmp .Lerror_entry_from_usermode_swapgs + SWAPGS + jmp .Lerror_entry_done .Lbstep_iret: /* Fix truncated RIP */ @@ -1423,3 +1438,14 @@ ENTRY(ignore_sysret) mov $-ENOSYS, %eax sysret END(ignore_sysret) + +ENTRY(rewind_stack_do_exit) + /* Prevent any naive code from trying to unwind to our caller. */ + xorl %ebp, %ebp + + movq PER_CPU_VAR(cpu_current_top_of_stack), %rax + leaq -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%rax), %rsp + + call do_exit +1: jmp 1b +END(rewind_stack_do_exit) |