From dd8e2d9ae64fa4348530df3e45e9f874d807a1c2 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 25 Feb 2020 23:08:05 +0100 Subject: [PATCH] x86/entry: Move irq tracing on syscall entry to C-code Now that the C entry points are safe, move the irq flags tracing code into the entry helper: - Invoke lockdep before calling into context tracking - Use the safe trace_hardirqs_on_prepare() trace function after context tracking established state and RCU is watching. enter_from_user_mode() is also still invoked from the exception/interrupt entry code which still contains the ASM irq flags tracing. So this is just a redundant and harmless invocation of tracing / lockdep until these are removed as well. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134340.611961721@linutronix.de --- arch/x86/entry/common.c | 21 +++++++++++++++++++-- arch/x86/entry/entry_32.S | 12 ------------ arch/x86/entry/entry_64.S | 2 -- arch/x86/entry/entry_64_compat.S | 18 ------------------ 4 files changed, 19 insertions(+), 34 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 9892fb7..7473c12 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -40,19 +40,36 @@ #include #ifdef CONFIG_CONTEXT_TRACKING -/* Called on entry from user mode with IRQs off. */ +/** + * enter_from_user_mode - Establish state when coming from user mode + * + * Syscall entry disables interrupts, but user mode is traced as interrupts + * enabled. Also with NO_HZ_FULL RCU might be idle. + * + * 1) Tell lockdep that interrupts are disabled + * 2) Invoke context tracking if enabled to reactivate RCU + * 3) Trace interrupts off state + */ __visible noinstr void enter_from_user_mode(void) { enum ctx_state state = ct_state(); + lockdep_hardirqs_off(CALLER_ADDR0); user_exit_irqoff(); instrumentation_begin(); CT_WARN_ON(state != CONTEXT_USER); + trace_hardirqs_off_prepare(); instrumentation_end(); } #else -static inline void enter_from_user_mode(void) {} +static __always_inline void enter_from_user_mode(void) +{ + lockdep_hardirqs_off(CALLER_ADDR0); + instrumentation_begin(); + trace_hardirqs_off_prepare(); + instrumentation_end(); +} #endif static noinstr void exit_to_user_mode(void) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index bf0082b..65704e0 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -967,12 +967,6 @@ SYM_FUNC_START(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 */ @@ -1082,12 +1076,6 @@ SYM_FUNC_START(entry_INT80_32) SAVE_ALL pt_regs_ax=$-ENOSYS switch_stacks=1 /* save rest */ - /* - * User mode is traced as though IRQs are on, and the interrupt gate - * turned them off. - */ - TRACE_IRQS_OFF - movl %esp, %eax call do_int80_syscall_32 .Lsyscall_32_done: diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index b199f43..9e34fe8 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -167,8 +167,6 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL) PUSH_AND_CLEAR_REGS rax=$-ENOSYS - TRACE_IRQS_OFF - /* IRQs are off. */ movq %rax, %rdi movq %rsp, %rsi diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index f1d3cca..e2e8bd7 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -129,12 +129,6 @@ SYM_FUNC_START(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 */ @@ -247,12 +241,6 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_after_hwframe, SYM_L_GLOBAL) 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 */ @@ -403,12 +391,6 @@ SYM_CODE_START(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: -- 2.7.4