From 8cf868affdc459beee1a941df0cfaba1673740e3 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 28 Nov 2016 13:03:21 -0500 Subject: tracing: Have the reg function allow to fail Some tracepoints have a registration function that gets enabled when the tracepoint is enabled. There may be cases that the registraction function must fail (for example, can't allocate enough memory). In this case, the tracepoint should also fail to register, otherwise the user would not know why the tracepoint is not working. Cc: David Howells Cc: Seiji Aguchi Cc: Anton Blanchard Cc: Mathieu Desnoyers Signed-off-by: Steven Rostedt --- arch/powerpc/include/asm/trace.h | 4 ++-- arch/powerpc/platforms/powernv/opal-tracepoints.c | 6 ++++-- arch/powerpc/platforms/pseries/lpar.c | 6 ++++-- arch/x86/include/asm/trace/exceptions.h | 2 +- arch/x86/include/asm/trace/irq_vectors.h | 2 +- arch/x86/kernel/tracepoint.c | 3 ++- 6 files changed, 14 insertions(+), 9 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h index 32e36b16773f..c05cef6ee06c 100644 --- a/arch/powerpc/include/asm/trace.h +++ b/arch/powerpc/include/asm/trace.h @@ -54,7 +54,7 @@ DEFINE_EVENT(ppc64_interrupt_class, timer_interrupt_exit, ); #ifdef CONFIG_PPC_PSERIES -extern void hcall_tracepoint_regfunc(void); +extern int hcall_tracepoint_regfunc(void); extern void hcall_tracepoint_unregfunc(void); TRACE_EVENT_FN_COND(hcall_entry, @@ -104,7 +104,7 @@ TRACE_EVENT_FN_COND(hcall_exit, #endif #ifdef CONFIG_PPC_POWERNV -extern void opal_tracepoint_regfunc(void); +extern int opal_tracepoint_regfunc(void); extern void opal_tracepoint_unregfunc(void); TRACE_EVENT_FN(opal_entry, diff --git a/arch/powerpc/platforms/powernv/opal-tracepoints.c b/arch/powerpc/platforms/powernv/opal-tracepoints.c index 1e496b780efd..3c447002edff 100644 --- a/arch/powerpc/platforms/powernv/opal-tracepoints.c +++ b/arch/powerpc/platforms/powernv/opal-tracepoints.c @@ -6,9 +6,10 @@ #ifdef HAVE_JUMP_LABEL struct static_key opal_tracepoint_key = STATIC_KEY_INIT; -void opal_tracepoint_regfunc(void) +int opal_tracepoint_regfunc(void) { static_key_slow_inc(&opal_tracepoint_key); + return 0; } void opal_tracepoint_unregfunc(void) @@ -25,9 +26,10 @@ void opal_tracepoint_unregfunc(void) /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ extern long opal_tracepoint_refcount; -void opal_tracepoint_regfunc(void) +int opal_tracepoint_regfunc(void) { opal_tracepoint_refcount++; + return 0; } void opal_tracepoint_unregfunc(void) diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index aa35245d8d6d..c0423ce3955c 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -661,9 +661,10 @@ EXPORT_SYMBOL(arch_free_page); #ifdef HAVE_JUMP_LABEL struct static_key hcall_tracepoint_key = STATIC_KEY_INIT; -void hcall_tracepoint_regfunc(void) +int hcall_tracepoint_regfunc(void) { static_key_slow_inc(&hcall_tracepoint_key); + return 0; } void hcall_tracepoint_unregfunc(void) @@ -680,9 +681,10 @@ void hcall_tracepoint_unregfunc(void) /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ extern long hcall_tracepoint_refcount; -void hcall_tracepoint_regfunc(void) +int hcall_tracepoint_regfunc(void) { hcall_tracepoint_refcount++; + return 0; } void hcall_tracepoint_unregfunc(void) diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h index 2fbc66c7885b..2422b14c50a7 100644 --- a/arch/x86/include/asm/trace/exceptions.h +++ b/arch/x86/include/asm/trace/exceptions.h @@ -6,7 +6,7 @@ #include -extern void trace_irq_vector_regfunc(void); +extern int trace_irq_vector_regfunc(void); extern void trace_irq_vector_unregfunc(void); DECLARE_EVENT_CLASS(x86_exceptions, diff --git a/arch/x86/include/asm/trace/irq_vectors.h b/arch/x86/include/asm/trace/irq_vectors.h index 38a09a13a9bc..32dd6a9e343c 100644 --- a/arch/x86/include/asm/trace/irq_vectors.h +++ b/arch/x86/include/asm/trace/irq_vectors.h @@ -6,7 +6,7 @@ #include -extern void trace_irq_vector_regfunc(void); +extern int trace_irq_vector_regfunc(void); extern void trace_irq_vector_unregfunc(void); DECLARE_EVENT_CLASS(x86_irq_vector, diff --git a/arch/x86/kernel/tracepoint.c b/arch/x86/kernel/tracepoint.c index 1c113db9ed57..15515132bf0d 100644 --- a/arch/x86/kernel/tracepoint.c +++ b/arch/x86/kernel/tracepoint.c @@ -34,7 +34,7 @@ static void switch_idt(void *arg) local_irq_restore(flags); } -void trace_irq_vector_regfunc(void) +int trace_irq_vector_regfunc(void) { mutex_lock(&irq_vector_mutex); if (!trace_irq_vector_refcount) { @@ -44,6 +44,7 @@ void trace_irq_vector_regfunc(void) } trace_irq_vector_refcount++; mutex_unlock(&irq_vector_mutex); + return 0; } void trace_irq_vector_unregfunc(void) -- cgit v1.2.3 From 847fa1a6d3d00f3bdf68ef5fa4a786f644a0dd67 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 8 Dec 2016 12:48:26 -0500 Subject: ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it With new binutils, gcc may get smart with its optimization and change a jmp from a 5 byte jump to a 2 byte one even though it was jumping to a global function. But that global function existed within a 2 byte radius, and gcc was able to optimize it. Unfortunately, that jump was also being modified when function graph tracing begins. Since ftrace expected that jump to be 5 bytes, but it was only two, it overwrote code after the jump, causing a crash. This was fixed for x86_64 with commit 8329e818f149, with the same subject as this commit, but nothing was done for x86_32. Cc: stable@vger.kernel.org Fixes: d61f82d06672 ("ftrace: use dynamic patching for updating mcount calls") Reported-by: Colin Ian King Tested-by: Colin Ian King Signed-off-by: Steven Rostedt --- arch/x86/entry/entry_32.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 21b352a11b49..edba8606b99a 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -889,8 +889,8 @@ ftrace_graph_call: jmp ftrace_stub #endif -.globl ftrace_stub -ftrace_stub: +/* This is weak to keep gas from relaxing the jumps */ +WEAK(ftrace_stub) ret END(ftrace_caller) -- cgit v1.2.3