[PATCH 5/8] RISCV64: Add 'bt' command support
Xianting Tian
xianting.tian at linux.alibaba.com
Sat Jul 16 21:29:26 PDT 2022
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 <xianting.tian at linux.alibaba.com>
---
netdump.c | 13 +++
riscv64.c | 283 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 296 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;
+
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 465834f..c00ce90 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);
@@ -650,6 +661,275 @@ no_page:
return FALSE;
}
+/*
+ * 'bt -f' commend 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;
+}
+
+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;
+ }
+
+ 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, ¤t, &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 (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_init_active_task_regs(void)
{
@@ -967,6 +1247,8 @@ 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;
@@ -987,6 +1269,7 @@ 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
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