From 9a7c348ba6a46f6270d4fe49577649dad5664fe7 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Fri, 19 Aug 2016 06:52:57 -0500 Subject: ftrace: Add return address pointer to ftrace_ret_stack Storing this value will help prevent unwinders from getting out of sync with the function graph tracer ret_stack. Now instead of needing a stateful iterator, they can compare the return address pointer to find the right ret_stack entry. Note that an array of 50 ftrace_ret_stack structs is allocated for every task. So when an arch implements this, it will add either 200 or 400 bytes of memory usage per task (depending on whether it's a 32-bit or 64-bit platform). Signed-off-by: Josh Poimboeuf Acked-by: Steven Rostedt Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Byungchul Park Cc: Denys Vlasenko Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Nilay Vaish Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt index dd5f916..a273dd0 100644 --- a/Documentation/trace/ftrace-design.txt +++ b/Documentation/trace/ftrace-design.txt @@ -203,6 +203,17 @@ along to ftrace_push_return_trace() instead of a stub value of 0. Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer. +HAVE_FUNCTION_GRAPH_RET_ADDR_PTR +-------------------------------- + +An arch may pass in a pointer to the return address on the stack. This +prevents potential stack unwinding issues where the unwinder gets out of +sync with ret_stack and the wrong addresses are reported by +ftrace_graph_ret_addr(). + +Adding support for it is easy: just define the macro in asm/ftrace.h and +pass the return address pointer as the 'retp' argument to +ftrace_push_return_trace(). HAVE_FTRACE_NMI_ENTER --------------------- diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 709ee1d..3f17594 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -218,7 +218,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, } err = ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer); + frame_pointer, NULL); if (err == -EBUSY) { *parent = old; return; diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index ebecf9a..40ad08a 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -138,7 +138,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, return; err = ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer); + frame_pointer, NULL); if (err == -EBUSY) return; else diff --git a/arch/blackfin/kernel/ftrace.c b/arch/blackfin/kernel/ftrace.c index 095de0f..8dad758 100644 --- a/arch/blackfin/kernel/ftrace.c +++ b/arch/blackfin/kernel/ftrace.c @@ -107,7 +107,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, return; if (ftrace_push_return_trace(*parent, self_addr, &trace.depth, - frame_pointer) == -EBUSY) + frame_pointer, NULL) == -EBUSY) return; trace.func = self_addr; diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c index fc7b48a..d57563c 100644 --- a/arch/microblaze/kernel/ftrace.c +++ b/arch/microblaze/kernel/ftrace.c @@ -63,7 +63,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) return; } - err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0); + err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL); if (err == -EBUSY) { *parent = old; return; diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c index 937c54b..30a3b75 100644 --- a/arch/mips/kernel/ftrace.c +++ b/arch/mips/kernel/ftrace.c @@ -382,8 +382,8 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, if (unlikely(faulted)) goto out; - if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp) - == -EBUSY) { + if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp, + NULL) == -EBUSY) { *parent_ra_addr = old_parent_ra; return; } diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c index a828a0a..5a5506a 100644 --- a/arch/parisc/kernel/ftrace.c +++ b/arch/parisc/kernel/ftrace.c @@ -48,7 +48,7 @@ static void __hot prepare_ftrace_return(unsigned long *parent, return; if (ftrace_push_return_trace(old, self_addr, &trace.depth, - 0 ) == -EBUSY) + 0, NULL) == -EBUSY) return; /* activate parisc_return_to_handler() as return point */ diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index cc52d97..a95639b 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -593,7 +593,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip) if (!ftrace_graph_entry(&trace)) goto out; - if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY) + if (ftrace_push_return_trace(parent, ip, &trace.depth, 0, + NULL) == -EBUSY) goto out; parent = return_hooker; diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 0f7bfeb..60a8a4e 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -209,7 +209,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip) /* Only trace if the calling function expects to. */ if (!ftrace_graph_entry(&trace)) goto out; - if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY) + if (ftrace_push_return_trace(parent, ip, &trace.depth, 0, + NULL) == -EBUSY) goto out; parent = (unsigned long) return_to_handler; out: diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c index 38993e0..95eccd4 100644 --- a/arch/sh/kernel/ftrace.c +++ b/arch/sh/kernel/ftrace.c @@ -382,7 +382,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) return; } - err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0); + err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL); if (err == -EBUSY) { __raw_writel(old, parent); return; diff --git a/arch/sparc/kernel/ftrace.c b/arch/sparc/kernel/ftrace.c index 0a2d2dd..6bcff69 100644 --- a/arch/sparc/kernel/ftrace.c +++ b/arch/sparc/kernel/ftrace.c @@ -131,7 +131,7 @@ unsigned long prepare_ftrace_return(unsigned long parent, return parent + 8UL; if (ftrace_push_return_trace(parent, self_addr, &trace.depth, - frame_pointer) == -EBUSY) + frame_pointer, NULL) == -EBUSY) return parent + 8UL; trace.func = self_addr; diff --git a/arch/tile/kernel/ftrace.c b/arch/tile/kernel/ftrace.c index 4a57208..b827a41 100644 --- a/arch/tile/kernel/ftrace.c +++ b/arch/tile/kernel/ftrace.c @@ -184,7 +184,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, *parent = return_hooker; err = ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer); + frame_pointer, NULL); if (err == -EBUSY) { *parent = old; return; diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index d036cfb..ae3b1fb 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -1029,7 +1029,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, } if (ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer) == -EBUSY) { + frame_pointer, NULL) == -EBUSY) { *parent = old; return; } diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 4ad9ccc..483e02a 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -798,6 +798,9 @@ struct ftrace_ret_stack { #ifdef HAVE_FUNCTION_GRAPH_FP_TEST unsigned long fp; #endif +#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR + unsigned long *retp; +#endif }; /* @@ -809,7 +812,7 @@ extern void return_to_handler(void); extern int ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, - unsigned long frame_pointer); + unsigned long frame_pointer, unsigned long *retp); /* * Sometimes we don't want to trace a function with the function diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 0e03ed0..f7212ec 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -119,7 +119,7 @@ print_graph_duration(struct trace_array *tr, unsigned long long duration, /* Add a function return address to the trace stack on thread info.*/ int ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, - unsigned long frame_pointer) + unsigned long frame_pointer, unsigned long *retp) { unsigned long long calltime; int index; @@ -174,6 +174,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, #ifdef HAVE_FUNCTION_GRAPH_FP_TEST current->ret_stack[index].fp = frame_pointer; #endif +#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR + current->ret_stack[index].retp = retp; +#endif *depth = current->curr_ret_stack; return 0; -- cgit v0.10.2