diff options
| -rw-r--r-- | arch/arm/oprofile/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm/oprofile/backtrace.c | 144 | ||||
| -rw-r--r-- | arch/arm/oprofile/init.c | 2 | ||||
| -rw-r--r-- | arch/arm/oprofile/op_arm_model.h | 2 |
4 files changed, 149 insertions, 1 deletions
diff --git a/arch/arm/oprofile/Makefile b/arch/arm/oprofile/Makefile index ba1a6e9f2b2..8ffb523e6c7 100644 --- a/arch/arm/oprofile/Makefile +++ b/arch/arm/oprofile/Makefile @@ -6,6 +6,6 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \ oprofilefs.o oprofile_stats.o \ timer_int.o ) -oprofile-y := $(DRIVER_OBJS) init.o +oprofile-y := $(DRIVER_OBJS) init.o backtrace.o oprofile-$(CONFIG_CPU_XSCALE) += common.o op_model_xscale.o diff --git a/arch/arm/oprofile/backtrace.c b/arch/arm/oprofile/backtrace.c new file mode 100644 index 00000000000..ec58d3e2eb8 --- /dev/null +++ b/arch/arm/oprofile/backtrace.c @@ -0,0 +1,144 @@ +/* + * Arm specific backtracing code for oprofile + * + * Copyright 2005 Openedhand Ltd. + * + * Author: Richard Purdie <rpurdie@openedhand.com> + * + * Based on i386 oprofile backtrace code by John Levon, David Smith + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/oprofile.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <asm/ptrace.h> +#include <asm/uaccess.h> + + +/* + * The registers we're interested in are at the end of the variable + * length saved register structure. The fp points at the end of this + * structure so the address of this struct is: + * (struct frame_tail *)(xxx->fp)-1 + */ +struct frame_tail { + struct frame_tail *fp; + unsigned long sp; + unsigned long lr; +} __attribute__((packed)); + + +#ifdef CONFIG_FRAME_POINTER +static struct frame_tail* kernel_backtrace(struct frame_tail *tail) +{ + oprofile_add_trace(tail->lr); + + /* frame pointers should strictly progress back up the stack + * (towards higher addresses) */ + if (tail >= tail->fp) + return NULL; + + return tail->fp-1; +} +#endif + +static struct frame_tail* user_backtrace(struct frame_tail *tail) +{ + struct frame_tail buftail; + + /* hardware pte might not be valid due to dirty/accessed bit emulation + * so we use copy_from_user and benefit from exception fixups */ + if (copy_from_user(&buftail, tail, sizeof(struct frame_tail))) + return NULL; + + oprofile_add_trace(buftail.lr); + + /* frame pointers should strictly progress back up the stack + * (towards higher addresses) */ + if (tail >= buftail.fp) + return NULL; + + return buftail.fp-1; +} + +/* Compare two addresses and see if they're on the same page */ +#define CMP_ADDR_EQUAL(x,y,offset) ((((unsigned long) x) >> PAGE_SHIFT) \ + == ((((unsigned long) y) + offset) >> PAGE_SHIFT)) + +/* check that the page(s) containing the frame tail are present */ +static int pages_present(struct frame_tail *tail) +{ + struct mm_struct * mm = current->mm; + + if (!check_user_page_readable(mm, (unsigned long)tail)) + return 0; + + if (CMP_ADDR_EQUAL(tail, tail, 8)) + return 1; + + if (!check_user_page_readable(mm, ((unsigned long)tail) + 8)) + return 0; + + return 1; +} + +/* + * | | /\ Higher addresses + * | | + * --------------- stack base (address of current_thread_info) + * | thread info | + * . . + * | stack | + * --------------- saved regs->ARM_fp value if valid (frame_tail address) + * . . + * --------------- struct pt_regs stored on stack (struct pt_regs *) + * | | + * . . + * | | + * --------------- %esp + * | | + * | | \/ Lower addresses + * + * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values + */ +static int valid_kernel_stack(struct frame_tail *tail, struct pt_regs *regs) +{ + unsigned long tailaddr = (unsigned long)tail; + unsigned long stack = (unsigned long)regs; + unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE; + + return (tailaddr > stack) && (tailaddr < stack_base); +} + +void arm_backtrace(struct pt_regs const *regs, unsigned int depth) +{ + struct frame_tail *tail; + unsigned long last_address = 0; + + tail = ((struct frame_tail *) regs->ARM_fp) - 1; + + if (!user_mode(regs)) { + +#ifdef CONFIG_FRAME_POINTER + while (depth-- && tail && valid_kernel_stack(tail, regs)) { + tail = kernel_backtrace(tail); + } +#endif + return; + } + + while (depth-- && tail && !((unsigned long) tail & 3)) { + if ((!CMP_ADDR_EQUAL(last_address, tail, 0) + || !CMP_ADDR_EQUAL(last_address, tail, 8)) + && !pages_present(tail)) + return; + last_address = (unsigned long) tail; + tail = user_backtrace(tail); + } +} + diff --git a/arch/arm/oprofile/init.c b/arch/arm/oprofile/init.c index cce3d3015eb..d315a3a86c8 100644 --- a/arch/arm/oprofile/init.c +++ b/arch/arm/oprofile/init.c @@ -20,6 +20,8 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) ret = pmu_init(ops, &op_xscale_spec); #endif + ops->backtrace = arm_backtrace; + return ret; } diff --git a/arch/arm/oprofile/op_arm_model.h b/arch/arm/oprofile/op_arm_model.h index 2d4caf4781a..2148d07484b 100644 --- a/arch/arm/oprofile/op_arm_model.h +++ b/arch/arm/oprofile/op_arm_model.h @@ -24,6 +24,8 @@ struct op_arm_model_spec { extern struct op_arm_model_spec op_xscale_spec; #endif +extern void arm_backtrace(struct pt_regs * const regs, unsigned int depth); + extern int __init pmu_init(struct oprofile_operations *ops, struct op_arm_model_spec *spec); extern void pmu_exit(void); #endif /* OP_ARM_MODEL_H */ |