Interrupt state tracing can be safely done in C code. The few stack operations in assembly do not need to be covered.
Remove the now pointless indirection via .Lsyscall_32_done and jump to swapgs_restore_regs_and_return_to_usermode directly. Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/entry/common.c | 10 ++++++++++ arch/x86/entry/entry_32.S | 17 ----------------- arch/x86/entry/entry_64.S | 6 ------ arch/x86/entry/entry_64_compat.S | 30 ++++-------------------------- 4 files changed, 14 insertions(+), 49 deletions(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -218,6 +218,9 @@ static void exit_to_usermode_loop(struct user_enter_irqoff(); mds_user_clear_cpu_buffers(); + + /* The return to usermode reenables interrupts. Tell the tracer */ + trace_hardirqs_on(); } #define SYSCALL_EXIT_WORK_FLAGS \ @@ -279,6 +282,9 @@ static void syscall_slow_exit_work(struc { struct thread_info *ti; + /* User to kernel transition disabled interrupts. */ + trace_hardirqs_off(); + enter_from_user_mode(); local_irq_enable(); ti = current_thread_info(); @@ -351,6 +357,7 @@ static __always_inline void do_syscall_3 /* Handles int $0x80 */ __visible void do_int80_syscall_32(struct pt_regs *regs) { + trace_hardirqs_off(); enter_from_user_mode(); local_irq_enable(); do_syscall_32_irqs_on(regs); @@ -367,6 +374,9 @@ static __always_inline void do_syscall_3 unsigned long landing_pad = (unsigned long)current->mm->context.vdso + vdso_image_32.sym_int80_landing_pad; + /* User to kernel transition disabled interrupts. */ + trace_hardirqs_off(); + /* * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward * so that 'regs->ip -= 2' lands back on an int $0x80 instruction. --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -924,12 +924,6 @@ ENTRY(entry_SYSENTER_32) jnz .Lsysenter_fix_flags .Lsysenter_flags_fixed: - /* - * User mode is traced as though IRQs are on, and SYSENTER - * turned them off. - */ - TRACE_IRQS_OFF - movl %esp, %eax call do_fast_syscall_32 /* XEN PV guests always use IRET path */ @@ -939,8 +933,6 @@ ENTRY(entry_SYSENTER_32) STACKLEAK_ERASE /* Opportunistic SYSEXIT */ - TRACE_IRQS_ON /* User mode traces as IRQs on. */ - /* * Setup entry stack - we keep the pointer in %eax and do the * switch after almost all user-state is restored. @@ -1039,12 +1031,6 @@ ENTRY(entry_INT80_32) SAVE_ALL pt_regs_ax=$-ENOSYS switch_stacks=1 /* save rest */ - /* - * User mode is traced as though IRQs are on, and the interrupt gate - * turned them off. - */ - TRACE_IRQS_OFF - movl %esp, %eax call do_int80_syscall_32 .Lsyscall_32_done: @@ -1052,11 +1038,8 @@ ENTRY(entry_INT80_32) STACKLEAK_ERASE restore_all: - TRACE_IRQS_IRET SWITCH_TO_ENTRY_STACK -.Lrestore_all_notrace: CHECK_AND_APPLY_ESPFIX -.Lrestore_nocheck: /* Switch back to user CR3 */ SWITCH_TO_USER_CR3 scratch_reg=%eax --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -167,15 +167,11 @@ GLOBAL(entry_SYSCALL_64_after_hwframe) PUSH_AND_CLEAR_REGS rax=$-ENOSYS - TRACE_IRQS_OFF - /* IRQs are off. */ movq %rax, %rdi movq %rsp, %rsi call do_syscall_64 /* returns with IRQs disabled */ - TRACE_IRQS_IRETQ /* we're about to change IF */ - /* * Try to use SYSRET instead of IRET if we're returning to * a completely clean 64-bit userspace context. If we're not, @@ -342,7 +338,6 @@ ENTRY(ret_from_fork) UNWIND_HINT_REGS movq %rsp, %rdi call syscall_return_slowpath /* returns with IRQs disabled */ - TRACE_IRQS_ON /* user mode is traced as IRQS on */ jmp swapgs_restore_regs_and_return_to_usermode 1: @@ -606,7 +601,6 @@ END(common_spurious) GLOBAL(retint_user) mov %rsp,%rdi call prepare_exit_to_usermode - TRACE_IRQS_IRETQ GLOBAL(swapgs_restore_regs_and_return_to_usermode) #ifdef CONFIG_DEBUG_ENTRY --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -129,17 +129,11 @@ ENTRY(entry_SYSENTER_compat) jnz .Lsysenter_fix_flags .Lsysenter_flags_fixed: - /* - * User mode is traced as though IRQs are on, and SYSENTER - * turned them off. - */ - TRACE_IRQS_OFF - movq %rsp, %rdi call do_fast_syscall_32 /* XEN PV guests always use IRET path */ - ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \ - "jmp .Lsyscall_32_done", X86_FEATURE_XENPV + ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \ + "jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV jmp sysret32_from_system_call .Lsysenter_fix_flags: @@ -247,17 +241,11 @@ GLOBAL(entry_SYSCALL_compat_after_hwfram pushq $0 /* pt_regs->r15 = 0 */ xorl %r15d, %r15d /* nospec r15 */ - /* - * User mode is traced as though IRQs are on, and SYSENTER - * turned them off. - */ - TRACE_IRQS_OFF - movq %rsp, %rdi call do_fast_syscall_32 /* XEN PV guests always use IRET path */ - ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \ - "jmp .Lsyscall_32_done", X86_FEATURE_XENPV + ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \ + "jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV /* Opportunistic SYSRET */ sysret32_from_system_call: @@ -266,7 +254,6 @@ GLOBAL(entry_SYSCALL_compat_after_hwfram * stack. So let's erase the thread stack right now. */ STACKLEAK_ERASE - TRACE_IRQS_ON /* User mode traces as IRQs on. */ movq RBX(%rsp), %rbx /* pt_regs->rbx */ movq RBP(%rsp), %rbp /* pt_regs->rbp */ movq EFLAGS(%rsp), %r11 /* pt_regs->flags (in r11) */ @@ -403,17 +390,8 @@ ENTRY(entry_INT80_compat) xorl %r15d, %r15d /* nospec r15 */ cld - /* - * User mode is traced as though IRQs are on, and the interrupt - * gate turned them off. - */ - TRACE_IRQS_OFF - movq %rsp, %rdi call do_int80_syscall_32 -.Lsyscall_32_done: - /* Go back to user mode. */ - TRACE_IRQS_ON jmp swapgs_restore_regs_and_return_to_usermode END(entry_INT80_compat)
