mips堆栈回溯相关资料

Submitter Gergely Kis Date 2011-05-13 12:38:05 Message ID <1305290285-13818-3-git-send-email-gergely@homejinni.com> Download mbox | patch Permalink /patch/2376/ State New Headers show Comments Gergely Kis - 2011-05-13 12:38:05 From: Daniel Kalmar <kalmard@homejinni.com> Stack unwinding is done by code examination. For kernelspace, the already existing unwind function is utilized that uses kallsyms to quickly find the beginning of functions. For userspace a new function was added that examines code at and before the pc. Signed-off-by: Daniel Kalmar <kalmard@homejinni.com> Signed-off-by: Gergely Kis <gergely@homejinni.com> --- arch/mips/oprofile/Makefile | 2 +- arch/mips/oprofile/backtrace.c | 173 ++++++++++++++++++++++++++++++++++++++++ arch/mips/oprofile/common.c | 1 + arch/mips/oprofile/op_impl.h | 2 + 4 files changed, 177 insertions(+), 1 deletions(-) create mode 100644 arch/mips/oprofile/backtrace.c Patch diff --git a/arch/mips/oprofile/Makefile b/arch/mips/oprofile/Makefile index 4b9d704..29f2f13 100644 --- a/arch/mips/oprofile/Makefile +++ b/arch/mips/oprofile/Makefile @@ -8,7 +8,7 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \ oprofilefs.o oprofile_stats.o \ timer_int.o ) -oprofile-y := $(DRIVER_OBJS) common.o +oprofile-y := $(DRIVER_OBJS) common.o backtrace.o oprofile-$(CONFIG_CPU_MIPS32) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_MIPS64) += op_model_mipsxx.o diff --git a/arch/mips/oprofile/backtrace.c b/arch/mips/oprofile/backtrace.c new file mode 100644 index 0000000..d508e9e --- /dev/null +++ b/arch/mips/oprofile/backtrace.c @@ -0,0 +1,173 @@ +#include <linux/oprofile.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <linux/uaccess.h> +#include <asm/ptrace.h> +#include <asm/stacktrace.h> +#include <linux/stacktrace.h> +#include <linux/kernel.h> +#include <asm/sections.h> +#include <asm/inst.h> + +struct stackframe { + unsigned long sp; + unsigned long pc; + unsigned long ra; +}; + +static inline int get_mem(unsigned long addr, unsigned long *result) +{ + unsigned long *address = (unsigned long *) addr; + if (!access_ok(VERIFY_READ, addr, sizeof(unsigned long))) + return -1; + if (__copy_from_user_inatomic(result, address, sizeof(unsigned long))) + return -3; + return 0; +} + +/* + * These two instruction helpers were taken from process.c + */ +static inline int is_ra_save_ins(union mips_instruction *ip) +{ + /* sw / sd $ra, offset($sp) */ + return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) + && ip->i_format.rs == 29 && ip->i_format.rt == 31; +} + +static inline int is_sp_move_ins(union mips_instruction *ip) +{ + /* addiu/daddiu sp,sp,-imm */ + if (ip->i_format.rs != 29 || ip->i_format.rt != 29) + return 0; + if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) + return 1; + return 0; +} + +/* + * Looks for specific instructions that mark the end of a function. + * This usually means we ran into the code area of the previous function. + */ +static inline int is_end_of_function_marker(union mips_instruction *ip) +{ + /* jr ra */ + if (ip->r_format.func == jr_op && ip->r_format.rs == 31) + return 1; + /* lui gp */ + if (ip->i_format.opcode == lui_op && ip->i_format.rt == 28) + return 1; + return 0; +} + +/* + * TODO for userspace stack unwinding: + * - handle cases where the stack is adjusted inside a function + * (generally doesn't happen) + * - find optimal value for max_instr_check + * - try to find a way to handle leaf functions + */ + +static inline int unwind_user_frame(struct stackframe *old_frame, + const unsigned int max_instr_check) +{ + struct stackframe new_frame = *old_frame; + off_t ra_offset = 0; + size_t stack_size = 0; + unsigned long addr; + + if (old_frame->pc == 0 || old_frame->sp == 0 || old_frame->ra == 0) + return -9; + + for (addr = new_frame.pc; (addr + max_instr_check > new_frame.pc) + && (!ra_offset || !stack_size); --addr) { + union mips_instruction ip; + + if (get_mem(addr, (unsigned long *) &ip)) + return -11; + + if (is_sp_move_ins(&ip)) { + int stack_adjustment = ip.i_format.simmediate; + if (stack_adjustment > 0) + /* This marks the end of the previous function, + which means we overran. */ + break; + stack_size = (unsigned) stack_adjustment; + } else if (is_ra_save_ins(&ip)) { + int ra_slot = ip.i_format.simmediate; + if (ra_slot < 0) + /* This shouldn't happen. */ + break; + ra_offset = ra_slot; + } else if (is_end_of_function_marker(&ip)) + break; + } + + if (!ra_offset || !stack_size) + return -1; + + if (ra_offset) { + new_frame.ra = old_frame->sp + ra_offset; + if (get_mem(new_frame.ra, &(new_frame.ra))) + return -13; + } + + if (stack_size) { + new_frame.sp = old_frame->sp + stack_size; + if (get_mem(new_frame.sp, &(new_frame.sp))) + return -14; + } + + if (new_frame.sp > old_frame->sp) + return -2; + + new_frame.pc = old_frame->ra; + *old_frame = new_frame; + + return 0; +} + +static inline void do_user_backtrace(unsigned long low_addr, + struct stackframe *frame, + unsigned int depth) { + const unsigned int max_instr_check = 512; + const unsigned long high_addr = low_addr + THREAD_SIZE; + + while (depth-- && !unwind_user_frame(frame, max_instr_check)) { + oprofile_add_trace(frame->ra); + if (frame->sp < low_addr || frame->sp > high_addr) + break; + } +} + +#ifndef CONFIG_KALLSYMS +static inline void do_kernel_backtrace(unsigned long low_addr, + struct stackframe *frame, + unsigned int depth) { } +#else +static inline void do_kernel_backtrace(unsigned long low_addr, + struct stackframe *frame, + unsigned int depth) { + while (depth-- && frame->pc) { + frame->pc = unwind_stack_by_address(low_addr, + &(frame->sp), + frame->pc, + &(frame->ra)); + oprofile_add_trace(frame->ra); + } +} +#endif + +void notrace op_mips_backtrace(struct pt_regs *const regs, unsigned int depth) +{ + struct stackframe frame = { .sp = regs->regs[29], + .pc = regs->cp0_epc, + .ra = regs->regs[31] }; + const int userspace = user_mode(regs); + const unsigned long low_addr = ALIGN(frame.sp, THREAD_SIZE); + + if (userspace) + do_user_backtrace(low_addr, &frame, depth); + else + do_kernel_backtrace(low_addr, &frame, depth); +} diff --git a/arch/mips/oprofile/common.c b/arch/mips/oprofile/common.c index f9eb1ab..d1f2d4c 100644 --- a/arch/mips/oprofile/common.c +++ b/arch/mips/oprofile/common.c @@ -115,6 +115,7 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) ops->start = op_mips_start; ops->stop = op_mips_stop; ops->cpu_type = lmodel->cpu_type; + ops->backtrace = op_mips_backtrace; printk(KERN_INFO "oprofile: using %s performance monitoring.\n", lmodel->cpu_type); diff --git a/arch/mips/oprofile/op_impl.h b/arch/mips/oprofile/op_impl.h index f04b54f..7c2da27 100644 --- a/arch/mips/oprofile/op_impl.h +++ b/arch/mips/oprofile/op_impl.h @@ -36,4 +36,6 @@ struct op_mips_model { unsigned char num_counters; }; +void op_mips_backtrace(struct pt_regs * const regs, unsigned int depth); + #endif