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 <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064956.672965407@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 48ef7bb32c4269331ceb2332b8e6bf5faffcb3de..0092da1c056f2b8d0525f83103486ed7abe0b332 100644 (file)
--- 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 4dbb336a1fdd1bacfbf294ffef2a4a43a81d924a..2731b94717706230fd5122f3bcf1cee7d2bf2d04 100644 (file)
--- 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 01fd0a7f48cd2f97dac2c1fd20e809e17975ad34..b4f322d6c95ff9e9f735a3174bac9268c53b48fa 100644 (file)
--- 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 d04e30e3c0ffd3f255f50e595c0ab0f919fddc70..6ed9242b5fa7662861eea051da41d146dda31d85 100644 (file)
--- 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 2a1fa10c6a98682a2db282a840f7e19f5466039a..58d7b3a4ec2e5516c08dafe138e147e41c532658 100644 (file)
--- 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);