Sorry - had wrong lists on original message Add ftrace function-graph tracer support for ARM.
This includes adding code in mcount to check for (and call) a registered function graph trace entry routine, and adding code to support a return trampoline, to catch the function exit. IRQENTRY_TEXT was added to vmlinux.lds.S (to eliminate a compiler error on kernel/trace/trace_functions_graph.c), although no routines were marked as __irq_entry. Signed-off-by: Tim Bird <[email protected]> --- arch/arm/Kconfig | 1 arch/arm/kernel/Makefile | 4 +-- arch/arm/kernel/entry-common.S | 36 +++++++++++++++++++++++++++++++- arch/arm/kernel/ftrace_graph.c | 46 +++++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/vmlinux.lds.S | 1 5 files changed, 85 insertions(+), 3 deletions(-) --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -18,6 +18,7 @@ config ARM select HAVE_KPROBES if (!XIP_KERNEL) select HAVE_KRETPROBES if (HAVE_KPROBES) select HAVE_FUNCTION_TRACER if (!XIP_KERNEL) + select HAVE_FUNCTION_GRAPH_TRACER if (!XIP_KERNEL) select HAVE_GENERIC_DMA_COHERENT select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZO --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -5,9 +5,8 @@ CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$(TEXT_OFFSET) AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET) -ifdef CONFIG_DYNAMIC_FTRACE CFLAGS_REMOVE_ftrace.o = -pg -endif +CFLAGS_REMOVE_ftrace_graph.o = -pg CFLAGS_REMOVE_return_address.o = -pg @@ -31,6 +30,7 @@ obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o +obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace_graph.o obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o obj-$(CONFIG_KPROBES) += kprobes.o kprobes-decode.o obj-$(CONFIG_ATAGS_PROC) += atags.o --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -98,6 +98,11 @@ ENTRY(mcount) mov r0, lr sub r0, r0, #MCOUNT_INSN_SIZE +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + @ FIXTHIS - DYNAMIC_FTRACE does not support function graph tracing + @ when the dynamic work is revived, this should be supported as well +#endif + .globl mcount_call mcount_call: bl ftrace_stub @@ -144,8 +149,16 @@ ENTRY(mcount) adr r0, ftrace_stub cmp r0, r2 bne trace + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + ldr r1, =ftrace_graph_return + ldr r2, [r1] + cmp r0, r2 @ if *ftrace_graph_return != ftrace_stub + bne ftrace_graph_caller +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + ldr lr, [fp, #-4] @ restore lr - ldmia sp!, {r0-r3, pc} + ldmia sp!, {r0-r3, pc} @ return doing nothing trace: ldr r1, [fp, #-4] @ lr of instrumented routine @@ -156,6 +169,27 @@ trace: ldr lr, [fp, #-4] @ restore lr ldmia sp!, {r0-r3, pc} +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +ENTRY(ftrace_graph_caller) + sub r0, fp, #4 @ &lr of instrumented routine (&parent) + mov r1, lr @ instrumented routine (func) + sub r1, r1, #MCOUNT_INSN_SIZE + mov r2, fp @ frame pointer + bl prepare_ftrace_return + ldr lr, [fp, #-4] @ restore lr + ldmia sp!, {r0-r3, pc} + + .globl return_to_handler +return_to_handler: + stmdb sp!, {r0-r3} + mov r0, fp @ frame pointer + bl ftrace_return_to_handler + mov lr, r0 @ r0 has real ret addr + ldmia sp!, {r0-r3} + mov pc, lr + +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + #endif /* CONFIG_DYNAMIC_FTRACE */ .globl ftrace_stub --- /dev/null +++ b/arch/arm/kernel/ftrace_graph.c @@ -0,0 +1,46 @@ +/* + * function graph tracing support. + * + * Copyright (C) 2009 Tim Bird <[email protected]> + * + * For licencing details, see COPYING. + * + * Defines routine needed for ARM return trampoline for tracing + * function exits. + */ + +#include <linux/ftrace.h> + +/* + * Hook the return address and push it in the stack of return addrs + * in current thread info. + */ +void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, + unsigned long frame_pointer) +{ + unsigned long old; + + struct ftrace_graph_ent trace; + unsigned long return_hooker = (unsigned long) + &return_to_handler; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + old = *parent; + *parent = return_hooker; + + if (ftrace_push_return_trace(old, self_addr, &trace.depth, + frame_pointer) == -EBUSY) { + *parent = old; + return; + } + + trace.func = self_addr; + + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) { + current->curr_ret_stack--; + *parent = old; + } +} --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -91,6 +91,7 @@ SECTIONS SCHED_TEXT LOCK_TEXT KPROBES_TEXT + IRQENTRY_TEXT #ifdef CONFIG_MMU *(.fixup) #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
