From 11a7ffb01703c3bbb1e9b968893f4487a1b0b5a8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Aug 2017 08:47:22 +0200 Subject: [PATCH] x86/traps: Simplify pagefault tracing logic Make use of the new irqvector tracing static key and remove the duplicated trace_do_pagefault() implementation. If irq vector tracing is disabled, then the overhead of this is a single NOP5, which is a reasonable tradeoff to avoid duplicated code and the unholy macro mess. Signed-off-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20170828064956.672965407@linutronix.de Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_32.S | 8 ------ arch/x86/entry/entry_64.S | 13 +--------- arch/x86/include/asm/traps.h | 10 +------- arch/x86/kernel/kvm.c | 2 +- arch/x86/mm/fault.c | 49 ++++++++++-------------------------- 5 files changed, 16 insertions(+), 66 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 48ef7bb32c42..0092da1c056f 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -891,14 +891,6 @@ BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR, #endif /* CONFIG_HYPERV */ -#ifdef CONFIG_TRACING -ENTRY(trace_page_fault) - ASM_CLAC - pushl $trace_do_page_fault - jmp common_exception -END(trace_page_fault) -#endif - ENTRY(page_fault) ASM_CLAC pushl $do_page_fault diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 4dbb336a1fdd..2731b9471770 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -918,17 +918,6 @@ ENTRY(\sym) END(\sym) .endm -#ifdef CONFIG_TRACING -.macro trace_idtentry sym do_sym has_error_code:req -idtentry trace(\sym) trace(\do_sym) has_error_code=\has_error_code -idtentry \sym \do_sym has_error_code=\has_error_code -.endm -#else -.macro trace_idtentry sym do_sym has_error_code:req -idtentry \sym \do_sym has_error_code=\has_error_code -.endm -#endif - idtentry divide_error do_divide_error has_error_code=0 idtentry overflow do_overflow has_error_code=0 idtentry bounds do_bounds has_error_code=0 @@ -1096,7 +1085,7 @@ idtentry xen_stack_segment do_stack_segment has_error_code=1 #endif idtentry general_protection do_general_protection has_error_code=1 -trace_idtentry page_fault do_page_fault has_error_code=1 +idtentry page_fault do_page_fault has_error_code=1 #ifdef CONFIG_KVM_GUEST idtentry async_page_fault do_async_page_fault has_error_code=1 diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 01fd0a7f48cd..b4f322d6c95f 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -39,7 +39,6 @@ asmlinkage void machine_check(void); asmlinkage void simd_coprocessor_error(void); #ifdef CONFIG_TRACING -asmlinkage void trace_page_fault(void); #define trace_stack_segment stack_segment #define trace_divide_error divide_error #define trace_bounds bounds @@ -54,6 +53,7 @@ asmlinkage void trace_page_fault(void); #define trace_alignment_check alignment_check #define trace_simd_coprocessor_error simd_coprocessor_error #define trace_async_page_fault async_page_fault +#define trace_page_fault page_fault #endif dotraplinkage void do_divide_error(struct pt_regs *, long); @@ -74,14 +74,6 @@ asmlinkage struct pt_regs *sync_regs(struct pt_regs *); #endif dotraplinkage void do_general_protection(struct pt_regs *, long); dotraplinkage void do_page_fault(struct pt_regs *, unsigned long); -#ifdef CONFIG_TRACING -dotraplinkage void trace_do_page_fault(struct pt_regs *, unsigned long); -#else -static inline void trace_do_page_fault(struct pt_regs *regs, unsigned long error) -{ - do_page_fault(regs, error); -} -#endif dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *, long); dotraplinkage void do_coprocessor_error(struct pt_regs *, long); dotraplinkage void do_alignment_check(struct pt_regs *, long); diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index d04e30e3c0ff..6ed9242b5fa7 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -263,7 +263,7 @@ do_async_page_fault(struct pt_regs *regs, unsigned long error_code) switch (kvm_read_and_reset_pf_reason()) { default: - trace_do_page_fault(regs, error_code); + do_page_fault(regs, error_code); break; case KVM_PV_REASON_PAGE_NOT_PRESENT: /* page is swapped out by the host. */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 2a1fa10c6a98..58d7b3a4ec2e 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1254,10 +1254,6 @@ static inline bool smap_violation(int error_code, struct pt_regs *regs) * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. - * - * This function must have noinline because both callers - * {,trace_}do_page_fault() have notrace on. Having this an actual function - * guarantees there's a function trace entry. */ static noinline void __do_page_fault(struct pt_regs *regs, unsigned long error_code, @@ -1490,27 +1486,6 @@ good_area: } NOKPROBE_SYMBOL(__do_page_fault); -dotraplinkage void notrace -do_page_fault(struct pt_regs *regs, unsigned long error_code) -{ - unsigned long address = read_cr2(); /* Get the faulting address */ - enum ctx_state prev_state; - - /* - * We must have this function tagged with __kprobes, notrace and call - * read_cr2() before calling anything else. To avoid calling any kind - * of tracing machinery before we've observed the CR2 value. - * - * exception_{enter,exit}() contain all sorts of tracepoints. - */ - - prev_state = exception_enter(); - __do_page_fault(regs, error_code, address); - exception_exit(prev_state); -} -NOKPROBE_SYMBOL(do_page_fault); - -#ifdef CONFIG_TRACING static nokprobe_inline void trace_page_fault_entries(unsigned long address, struct pt_regs *regs, unsigned long error_code) @@ -1521,22 +1496,24 @@ trace_page_fault_entries(unsigned long address, struct pt_regs *regs, trace_page_fault_kernel(address, regs, error_code); } +/* + * We must have this function blacklisted from kprobes, tagged with notrace + * and call read_cr2() before calling anything else. To avoid calling any + * kind of tracing machinery before we've observed the CR2 value. + * + * exception_{enter,exit}() contains all sorts of tracepoints. + */ dotraplinkage void notrace -trace_do_page_fault(struct pt_regs *regs, unsigned long error_code) +do_page_fault(struct pt_regs *regs, unsigned long error_code) { - /* - * The exception_enter and tracepoint processing could - * trigger another page faults (user space callchain - * reading) and destroy the original cr2 value, so read - * the faulting address now. - */ - unsigned long address = read_cr2(); + unsigned long address = read_cr2(); /* Get the faulting address */ enum ctx_state prev_state; prev_state = exception_enter(); - trace_page_fault_entries(address, regs, error_code); + if (trace_irqvectors_enabled()) + trace_page_fault_entries(address, regs, error_code); + __do_page_fault(regs, error_code, address); exception_exit(prev_state); } -NOKPROBE_SYMBOL(trace_do_page_fault); -#endif /* CONFIG_TRACING */ +NOKPROBE_SYMBOL(do_page_fault); -- 2.20.1