<div dir="ltr"><div dir="ltr">On Mon, Aug 1, 2022 at 12:31 PM Xianting Tian <<a href="mailto:xianting.tian@linux.alibaba.com">xianting.tian@linux.alibaba.com</a>> wrote: </div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">1, Add the implementation to get stack frame from active & inactive task's stack. 2, Add 'bt -l' command support get a line number associated with a current pc address. 3, Add 'bt -f' command support to display all stack data contained in a frame With the patch, we can get the backtrace, crash> bt PID: 113 TASK: ff6000000226c200 CPU: 0 COMMAND: "sh" #0 [ff20000010333b90] riscv_crash_save_regs at ffffffff800078f8 #1 [ff20000010333cf0] panic at ffffffff806578c6 #2 [ff20000010333d50] sysrq_reset_seq_param_set at ffffffff8038c03c #3 [ff20000010333da0] __handle_sysrq at ffffffff8038c604 #4 [ff20000010333e00] write_sysrq_trigger at ffffffff8038cae4 #5 [ff20000010333e20] proc_reg_write at ffffffff801b7ee8 #6 [ff20000010333e40] vfs_write at ffffffff80152bb2 #7 [ff20000010333e80] ksys_write at ffffffff80152eda #8 [ff20000010333ed0] sys_write at ffffffff80152f52 crash> bt -l PID: 113 TASK: ff6000000226c200 CPU: 0 COMMAND: "sh" #0 [ff20000010333b90] riscv_crash_save_regs at ffffffff800078f8 /buildroot/qemu_riscv64_virt_defconfig/build/linux-custom/arch/riscv/kernel/crash_save_regs.S: 47 #1 [ff20000010333cf0] panic at ffffffff806578c6 /buildroot/qemu_riscv64_virt_defconfig/build/linux-custom/kernel/panic.c: 276 ... ... crash> bt -f PID: 113 TASK: ff6000000226c200 CPU: 0 COMMAND: "sh" #0 [ff20000010333b90] riscv_crash_save_regs at ffffffff800078f8 [PC: ffffffff800078f8 RA: ffffffff806578c6 SP: ff20000010333b90 SIZE: 352] ff20000010333b90: ff20000010333bb0 ffffffff800078f8 ff20000010333ba0: ffffffff8008862c ff20000010333b90 ff20000010333bb0: ffffffff810dde38 ff6000000226c200 ff20000010333bc0: ffffffff8032be68 0720072007200720 ... ... Signed-off-by: Xianting Tian <<a href="mailto:xianting.tian@linux.alibaba.com" target="_blank">xianting.tian@linux.alibaba.com</a>> --- netdump.c | 13 +++ riscv64.c | 287 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 300 insertions(+) diff --git a/netdump.c b/netdump.c index 4ec12a0..1f418e6 100644 --- a/netdump.c +++ b/netdump.c @@ -42,6 +42,7 @@ static void get_netdump_regs_ppc64(struct bt_info *, ulong *, ulong *); static void get_netdump_regs_arm(struct bt_info *, ulong *, ulong *); static void get_netdump_regs_arm64(struct bt_info *, ulong *, ulong *); static void get_netdump_regs_mips(struct bt_info *, ulong *, ulong *); +static void get_netdump_regs_riscv(struct bt_info *, ulong *, ulong *); static void check_dumpfile_size(char *); static int proc_kcore_init_32(FILE *, int); static int proc_kcore_init_64(FILE *, int); @@ -2675,6 +2676,10 @@ get_netdump_regs(struct bt_info *bt, ulong *eip, ulong *esp) return get_netdump_regs_mips(bt, eip, esp); break; + case EM_RISCV: + return get_netdump_regs_riscv(bt, eip, esp); + break; + </blockquote><div> </div><div>This looks weird. I guess that you are still following the old code changes. I would suggest using a better</div><div>code style as below, unless you have specific reasons.</div><div> </div><div>+ case EM_RISCV: + get_netdump_regs_riscv(bt, eip, esp); + break; +</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> default: error(FATAL, "support for ELF machine type %d not available\n", @@ -2931,6 +2936,8 @@ display_regs_from_elf_notes(int cpu, FILE *ofp) mips_display_regs_from_elf_notes(cpu, ofp); } else if (machine_type("MIPS64")) { mips64_display_regs_from_elf_notes(cpu, ofp); + } else if (machine_type("RISCV64")) { + riscv64_display_regs_from_elf_notes(cpu, ofp); } } @@ -3877,6 +3884,12 @@ get_netdump_regs_mips(struct bt_info *bt, ulong *eip, ulong *esp) machdep->get_stack_frame(bt, eip, esp); } +static void +get_netdump_regs_riscv(struct bt_info *bt, ulong *eip, ulong *esp) +{ + machdep->get_stack_frame(bt, eip, esp); +} + int is_partial_netdump(void) { diff --git a/riscv64.c b/riscv64.c index db37123..8bd35f7 100644 --- a/riscv64.c +++ b/riscv64.c @@ -33,6 +33,17 @@ static int riscv64_uvtop(struct task_context *tc, ulong vaddr, static int riscv64_kvtop(struct task_context *tc, ulong kvaddr, physaddr_t *paddr, int verbose); static void riscv64_cmd_mach(void); +static void riscv64_stackframe_init(void); +static void riscv64_back_trace_cmd(struct bt_info *bt); +static int riscv64_get_dumpfile_stack_frame(struct bt_info *bt, + ulong *nip, ulong *ksp); +static void riscv64_get_stack_frame(struct bt_info *bt, ulong *pcp, + ulong *spp); +static int riscv64_get_frame(struct bt_info *bt, ulong *pcp, + ulong *spp); +static void riscv64_display_full_frame(struct bt_info *bt, + struct riscv64_unwind_frame *current, + struct riscv64_unwind_frame *previous); static int riscv64_translate_pte(ulong, void *, ulonglong); static int riscv64_init_active_task_regs(void); static int riscv64_get_crash_notes(void); @@ -503,6 +514,279 @@ no_page: return FALSE; } +/* + * 'bt -f' command output + * Display all stack data contained in a frame + */ +static void +riscv64_display_full_frame(struct bt_info *bt, struct riscv64_unwind_frame *current, + struct riscv64_unwind_frame *previous) +{ + int i, u_idx; + ulong *up; + ulong words, addr; + char buf[BUFSIZE]; + + if (previous->sp < current->sp) + return; + + if (!(INSTACK(previous->sp, bt) && INSTACK(current->sp, bt))) + return; + + words = (previous->sp - current->sp) / sizeof(ulong) + 1; + addr = current->sp; + u_idx = (current->sp - bt->stackbase) / sizeof(ulong); + + for (i = 0; i < words; i++, u_idx++) { + if (!(i & 1)) + fprintf(fp, "%s %lx: ", i ? "\n" : "", addr); + + up = (ulong *)(&bt->stackbuf[u_idx*sizeof(ulong)]); + fprintf(fp, "%s ", format_stack_entry(bt, buf, *up, 0)); + addr += sizeof(ulong); + } + fprintf(fp, "\n"); + + return; </blockquote><div> ^^^^^^^ </div><div>Is it redundant? Could it be removed? </div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> +} + +static void +riscv64_stackframe_init(void) +{ + long task_struct_thread = MEMBER_OFFSET("task_struct", "thread"); + + /* from arch/riscv/include/asm/processor.h */ + long thread_reg_ra = MEMBER_OFFSET("thread_struct", "ra"); + long thread_reg_sp = MEMBER_OFFSET("thread_struct", "sp"); + long thread_reg_fp = MEMBER_OFFSET("thread_struct", "s"); + + if ((task_struct_thread == INVALID_OFFSET) || + (thread_reg_ra == INVALID_OFFSET) || + (thread_reg_sp == INVALID_OFFSET) || + (thread_reg_fp == INVALID_OFFSET) ) { + error(FATAL, + "cannot determine thread_struct offsets\n"); + return; </blockquote><div> ^^^^^^</div><div>The "return" has no chance to execute due to the "error(FATAL, ...)". </div><div> </div><div>Thanks.</div><div>Lianbo</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + } + + ASSIGN_OFFSET(task_struct_thread_context_pc) = + task_struct_thread + thread_reg_ra; + ASSIGN_OFFSET(task_struct_thread_context_sp) = + task_struct_thread + thread_reg_sp; + ASSIGN_OFFSET(task_struct_thread_context_fp) = + task_struct_thread + thread_reg_fp; +} + +static void +riscv64_dump_backtrace_entry(struct bt_info *bt, struct syment *sym, + struct riscv64_unwind_frame *current, + struct riscv64_unwind_frame *previous, int level) +{ + const char *name = sym ? sym->name : "(invalid)"; + struct load_module *lm; + char *name_plus_offset = NULL; + struct syment *symp; + ulong symbol_offset; + char buf[BUFSIZE]; + + if (bt->flags & BT_SYMBOL_OFFSET) { + symp = value_search(current->pc, &symbol_offset); + + if (symp && symbol_offset) + name_plus_offset = + value_to_symstr(current->pc, buf, bt->radix); + } + + fprintf(fp, "%s#%d [%016lx] %s at %016lx", + level < 10 ? " " : "", + level, + current->sp, + name_plus_offset ? name_plus_offset : name, + current->pc); + + if (module_symbol(current->pc, NULL, &lm, NULL, 0)) + fprintf(fp, " [%s]", lm->mod_name); + + fprintf(fp, "\n"); + + /* + * 'bt -l', get a line number associated with a current pc address. + */ + if (bt->flags & BT_LINE_NUMBERS) { + get_line_number(current->pc, buf, FALSE); + if (strlen(buf)) + fprintf(fp, " %s\n", buf); + } + + /* bt -f */ + if (bt->flags & BT_FULL) { + fprintf(fp, " " + "[PC: %016lx RA: %016lx SP: %016lx SIZE: %ld]\n", + current->pc, + previous->pc, + current->sp, + previous->sp - current->sp); + riscv64_display_full_frame(bt, current, previous); + } +} + +/* + * Unroll a kernel stack. + */ +static void +riscv64_back_trace_cmd(struct bt_info *bt) +{ + struct riscv64_unwind_frame current, previous; + struct stackframe curr_frame; + int level = 0; + + if (bt->flags & BT_REGS_NOT_FOUND) + return; + + current.pc = bt->instptr; + current.sp = bt->stkptr; + current.fp = bt->frameptr; + + if (!INSTACK(current.sp, bt)) + return; + + for (;;) { + struct syment *symbol = NULL; + struct stackframe *frameptr; + ulong low, high; + ulong offset; + + if (CRASHDEBUG(8)) + fprintf(fp, "level %d pc %#lx sp %lx fp 0x%lx\n", + level, current.pc, current.sp, current.fp); + + /* Validate frame pointer */ + low = current.sp + sizeof(struct stackframe); + high = bt->stacktop; + if (current.fp < low || current.fp > high || current.fp & 0x7) { + if (CRASHDEBUG(8)) + fprintf(fp, "fp 0x%lx sp 0x%lx low 0x%lx high 0x%lx\n", + current.fp, current.sp, low, high); + return; + } + + symbol = value_search(current.pc, &offset); + if (!symbol) + return; + + frameptr = (struct stackframe *)current.fp - 1; + if (!readmem((ulong)frameptr, KVADDR, &curr_frame, + sizeof(curr_frame), "get stack frame", RETURN_ON_ERROR)) + return; + + previous.pc = curr_frame.ra; + previous.fp = curr_frame.fp; + previous.sp = current.fp; + + riscv64_dump_backtrace_entry(bt, symbol, &current, &previous, level++); + + current.pc = previous.pc; + current.fp = previous.fp; + current.sp = previous.sp; + + if (CRASHDEBUG(8)) + fprintf(fp, "next %d pc %#lx sp %#lx fp %lx\n", + level, current.pc, current.sp, current.fp); + } +} + +/* + * Get a stack frame combination of pc and ra from the most relevant spot. + */ +static void +riscv64_get_stack_frame(struct bt_info *bt, ulong *pcp, ulong *spp) +{ + ulong ksp = 0, nip = 0; + int ret = 0; + + if (DUMPFILE() && is_task_active(bt->task)) + ret = riscv64_get_dumpfile_stack_frame(bt, &nip, &ksp); + else + ret = riscv64_get_frame(bt, &nip, &ksp); + + if (!ret) + error(WARNING, "cannot determine starting stack frame for task %lx\n", + bt->task); + + if (pcp) + *pcp = nip; + if (spp) + *spp = ksp; +} + +/* + * Get the starting point for the active cpu in a diskdump. + */ +static int +riscv64_get_dumpfile_stack_frame(struct bt_info *bt, ulong *nip, ulong *ksp) +{ + const struct machine_specific *ms = machdep->machspec; + struct riscv64_register *regs; + ulong epc, sp; + + if (!ms->crash_task_regs) { + bt->flags |= BT_REGS_NOT_FOUND; + return FALSE; + } + + /* + * We got registers for panic task from crash_notes. Just return them. + */ + regs = &ms->crash_task_regs[bt->tc->processor]; + epc = regs->regs[RISCV64_REGS_EPC]; + sp = regs->regs[RISCV64_REGS_SP]; + + /* + * Set stack frame ptr. + */ + bt->frameptr = regs->regs[RISCV64_REGS_FP]; + + if (nip) + *nip = epc; + if (ksp) + *ksp = sp; + + bt->machdep = regs; + + return TRUE; +} + +/* + * Do the work for riscv64_get_stack_frame() for non-active tasks. + * Get SP and PC values for idle tasks. + */ +static int +riscv64_get_frame(struct bt_info *bt, ulong *pcp, ulong *spp) +{ + if (!bt->tc || !(tt->flags & THREAD_INFO)) + return FALSE; + + if (!readmem(bt->task + OFFSET(task_struct_thread_context_pc), + KVADDR, pcp, sizeof(*pcp), + "thread_struct.ra", + RETURN_ON_ERROR)) + return FALSE; + + if (!readmem(bt->task + OFFSET(task_struct_thread_context_sp), + KVADDR, spp, sizeof(*spp), + "thread_struct.sp", + RETURN_ON_ERROR)) + return FALSE; + + if (!readmem(bt->task + OFFSET(task_struct_thread_context_fp), + KVADDR, &bt->frameptr, sizeof(bt->frameptr), + "thread_struct.fp", + RETURN_ON_ERROR)) + return FALSE; + + return TRUE; +} + static int riscv64_vtop_4level_4k(ulong *pgd, ulong vaddr, physaddr_t *paddr, int verbose) { @@ -983,6 +1267,8 @@ riscv64_init(int when) machdep->uvtop = riscv64_uvtop; machdep->kvtop = riscv64_kvtop; machdep->cmd_mach = riscv64_cmd_mach; + machdep->get_stack_frame = riscv64_get_stack_frame; + machdep->back_trace = riscv64_back_trace_cmd; machdep->vmalloc_start = riscv64_vmalloc_start; machdep->processor_speed = riscv64_processor_speed; @@ -1003,6 +1289,7 @@ riscv64_init(int when) case POST_GDB: machdep->section_size_bits = _SECTION_SIZE_BITS; machdep->max_physmem_bits = _MAX_PHYSMEM_BITS; + riscv64_stackframe_init(); riscv64_page_type_init(); if (!machdep->hz) -- 2.17.1 _______________________________________________ kexec mailing list <a href="mailto:kexec@lists.infradead.org" target="_blank">kexec@lists.infradead.org</a> <a href="http://lists.infradead.org/mailman/listinfo/kexec" rel="noreferrer" target="_blank">http://lists.infradead.org/mailman/listinfo/kexec</a> </blockquote></div></div>