On 2023/12/13 18:45, Song Shuai wrote:
> The patch introduces per-cpu overflow stacks for RISCV64 to let
> "bt" do backtrace on it and the 'help -m' command dispalys the
> addresss of each per-cpu overflow stack.
>
> TEST: a lkdtm DIRECT EXHAUST_STACK vmcore
>
> ```
> crash> bt
> PID: 1 TASK: ff600000000d8000 CPU: 1 COMMAND: "sh"
> #0 [ff6000001fc501c0] riscv_crash_save_regs at ffffffff8000a1dc
> #1 [ff6000001fc50320] panic at ffffffff808773ec
> #2 [ff6000001fc50380] walk_stackframe at ffffffff800056da
> PC: ffffffff80876a34 [memset+96]
> RA: ffffffff80563dc0 [recursive_loop+68]
> SP: ff2000000000fd50 CAUSE: 000000000000000f
> epc : ffffffff80876a34 ra : ffffffff80563dc0 sp : ff2000000000fd50
> gp : ffffffff81515d38 tp : 0000000000000000 t0 : ff2000000000fd58
> t1 : ff600000000d88c8 t2 : 6143203a6d74646b s0 : ff20000000010190
> s1 : 0000000000000012 a0 : ff2000000000fd58 a1 : 1212121212121212
> a2 : 0000000000000400 a3 : ff20000000010158 a4 : 0000000000000000
> a5 : 725bedba92260900 a6 : 000000000130e0f0 a7 : 0000000000000000
> s2 : ff2000000000fd58 s3 : ffffffff815170d8 s4 : ff20000000013e60
> s5 : 000000000000000e s6 : ff20000000013e60 s7 : 0000000000000000
> s8 : ff60000000861000 s9 : 00007fffc3641694 s10: 00007fffc3641690
> s11: 00005555796ed240 t3 : 0000000000010297 t4 : ffffffff80c17810
> t5 : ffffffff8195e7b8 t6 : ff20000000013b18
> status: 0000000200000120 badaddr: ff2000000000fd58
> cause: 000000000000000f orig_a0: 0000000000000000
> --- <OVERFLOW stack> ---
> #3 [ff2000000000fd50] memset at ffffffff80876a34
> #4 [ff20000000010190] recursive_loop at ffffffff80563e16
> #5 [ff200000000105d0] recursive_loop at ffffffff80563e16
> < recursive_loop ...>
> #16 [ff20000000013490] recursive_loop at ffffffff80563e16
> #17 [ff200000000138d0] recursive_loop at ffffffff80563e16
> #18 [ff20000000013d10] lkdtm_EXHAUST_STACK at ffffffff8088005e
> #19 [ff20000000013d30] lkdtm_do_action at ffffffff80563292
> #20 [ff20000000013d40] direct_entry at ffffffff80563474
> #21 [ff20000000013d70] full_proxy_write at ffffffff8032fb3a
> #22 [ff20000000013db0] vfs_write at ffffffff801d6414
> #23 [ff20000000013e60] ksys_write at ffffffff801d67b8
> #24 [ff20000000013eb0] __riscv_sys_write at ffffffff801d6832
> #25 [ff20000000013ec0] do_trap_ecall_u at ffffffff80884a20
> crash>
>
> crash> help -m
> <snip>
> irq_stack_size: 16384
> irq_stacks[0]: ff20000000000000
> irq_stacks[1]: ff20000000008000
> overflow_stack_size: 4096
> overflow_stacks[0]: ff6000001fa7a510
> overflow_stacks[1]: ff6000001fc4f510
> crash>
> ```
> Signed-off-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
> ---
> defs.h | 6 +++
> riscv64.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 120 insertions(+), 3 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 7b9fcce..5369d57 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -3656,6 +3656,9 @@ typedef signed int s32;
> #define VM_L5_2M (0x100)
> #define VM_L5_1G (0x200)
> #define IRQ_STACKS (0x400)
> +#define OVERFLOW_STACKS (0x800)
> +
> +#define RISCV64_OVERFLOW_STACK_SIZE (1 << 12)
>
> #define VM_FLAGS (VM_L3_4K | VM_L3_2M | VM_L3_1G | \
> VM_L4_4K | VM_L4_2M | VM_L4_1G | \
> @@ -7048,6 +7051,9 @@ struct machine_specific {
> struct riscv64_register *crash_task_regs;
> ulong irq_stack_size;
> ulong *irq_stacks;
> +
> + ulong overflow_stack_size;
> + ulong *overflow_stacks;
> };
> /* from arch/riscv/include/asm/pgtable-bits.h */
> #define _PAGE_PRESENT (machdep->machspec->_page_present)
> diff --git a/riscv64.c b/riscv64.c
> index a69dfe5..c5a85e8 100644
> --- a/riscv64.c
> +++ b/riscv64.c
> @@ -34,6 +34,7 @@ static int riscv64_kvtop(struct task_context *tc, ulong kvaddr,
> physaddr_t *paddr, int verbose);
> static void riscv64_cmd_mach(void);
> static void riscv64_irq_stack_init(void);
> +static void riscv64_overflow_stack_init(void);
> static void riscv64_stackframe_init(void);
> static void riscv64_back_trace_cmd(struct bt_info *bt);
> static int riscv64_eframe_search(struct bt_info *bt);
> @@ -59,9 +60,13 @@ static int riscv64_on_irq_stack(int , ulong);
> static int riscv64_on_process_stack(struct bt_info *, ulong );
> static void riscv64_set_process_stack(struct bt_info *);
> static void riscv64_set_irq_stack(struct bt_info *);
> +static int riscv64_on_overflow_stack(int, ulong);
> +static void riscv64_set_overflow_stack(struct bt_info *);
>
> #define REG_FMT "%016lx"
> #define SZ_2G 0x80000000
> +#define USER_MODE (0)
> +#define KERNEL_MODE (1)
I moved this "move" to the 2/3 patch due to a compilation error and
tweaked some indents and spaces, and applied.
https://github.com/crash-utility/crash/compare/edb2bd5...a694962
(ugh, I didn't notice that those stack addresses should be printed by
"mach" command like other architectures..)
Thanks,
Kazu
>
> /*
> * Holds registers during the crash.
> @@ -204,6 +209,8 @@ riscv64_dump_machdep_table(ulong arg)
> fprintf(fp, "%sKSYMS_START", others++ ? "|" : "");
> if (machdep->flags & IRQ_STACKS)
> fprintf(fp, "%sIRQ_STACKS", others++ ? "|" : "");
> + if (machdep->flags & OVERFLOW_STACKS)
> + fprintf(fp, "%sOVERFLOW_STACKS", others++ ? "|" : "");
> fprintf(fp, ")\n");
>
> fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
> @@ -268,6 +275,15 @@ riscv64_dump_machdep_table(ulong arg)
> fprintf(fp, " irq_stack_size: (unused)\n");
> fprintf(fp, " irq_stacks: (unused)\n");
> }
> + if (machdep->flags & OVERFLOW_STACKS) {
> + fprintf(fp, " overflow_stack_size: %ld\n", ms->overflow_stack_size);
> + for (i = 0; i < kt->cpus; i++)
> + fprintf(fp, " overflow_stacks[%d]: %lx\n",
> + i, ms->overflow_stacks[i]);
> + } else {
> + fprintf(fp, " overflow_stack_size: (unused)\n");
> + fprintf(fp, " overflow_stacks: (unused)\n");
> + }
> }
>
> static ulong
> @@ -682,6 +698,48 @@ riscv64_display_full_frame(struct bt_info *bt, struct riscv64_unwind_frame *curr
> fprintf(fp, "\n");
> }
>
> +
> +/*
> + * Gather Overflow stack values.
> + */
> +static void
> +riscv64_overflow_stack_init(void)
> +{
> + int i;
> + struct syment *sp;
> + struct gnu_request request, *req;
> + struct machine_specific *ms = machdep->machspec;
> + req = &request;
> +
> + if (symbol_exists("overflow_stack") &&
> + (sp = per_cpu_symbol_search("overflow_stack")) &&
> + get_symbol_type("overflow_stack", NULL, req)) {
> + if (CRASHDEBUG(1)) {
> + fprintf(fp, "overflow_stack: \n");
> + fprintf(fp, " type: %x, %s\n",
> + (int)req->typecode,
> + (req->typecode == TYPE_CODE_ARRAY) ?
> + "TYPE_CODE_ARRAY" : "other");
> + fprintf(fp, " target_typecode: %x, %s\n",
> + (int)req->target_typecode,
> + req->target_typecode == TYPE_CODE_INT ?
> + "TYPE_CODE_INT" : "other");
> + fprintf(fp, " target_length: %ld\n",
> + req->target_length);
> + fprintf(fp, " length: %ld\n", req->length);
> + }
> +
> + if (!(ms->overflow_stacks = (ulong *)malloc((size_t)(kt->cpus * sizeof(ulong)))))
> + error(FATAL, "cannot malloc overflow_stack addresses\n");
> +
> + ms->overflow_stack_size = RISCV64_OVERFLOW_STACK_SIZE;
> + machdep->flags |= OVERFLOW_STACKS;
> +
> + for (i = 0; i < kt->cpus; i++)
> + ms->overflow_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
> + }
> +}
> +
> /*
> * Gather IRQ stack values.
> */
> @@ -755,6 +813,23 @@ riscv64_on_irq_stack(int cpu, ulong stkptr)
> return FALSE;
> }
>
> +static int
> +riscv64_on_overflow_stack(int cpu, ulong stkptr)
> +{
> + struct machine_specific *ms = machdep->machspec;
> + ulong * stacks = ms->overflow_stacks;
> + ulong stack_size = ms->overflow_stack_size;
> +
> + if ((cpu >= kt->cpus) || (stacks == NULL) || !stack_size)
> + return FALSE;
> +
> + if ((stkptr >= stacks[cpu]) &&
> + (stkptr < (stacks[cpu] + stack_size)))
> + return TRUE;
> +
> + return FALSE;
> +}
> +
> static int
> riscv64_on_process_stack(struct bt_info *bt, ulong stkptr)
> {
> @@ -779,6 +854,16 @@ riscv64_set_irq_stack(struct bt_info *bt)
> alter_stackbuf(bt);
> }
>
> +static void
> +riscv64_set_overflow_stack(struct bt_info *bt)
> +{
> + struct machine_specific *ms = machdep->machspec;
> +
> + bt->stackbase = ms->overflow_stacks[bt->tc->processor];
> + bt->stacktop = bt->stackbase + ms->overflow_stack_size;
> + alter_stackbuf(bt);
> +}
> +
> static void
> riscv64_set_process_stack(struct bt_info *bt)
> {
> @@ -873,7 +958,7 @@ riscv64_back_trace_cmd(struct bt_info *bt)
> {
> struct riscv64_unwind_frame current, previous;
> struct stackframe curr_frame;
> - struct riscv64_register *regs, *irq_regs;
> + struct riscv64_register *regs, *irq_regs, *overflow_regs;
> int level = 0;
>
> if (bt->flags & BT_REGS_NOT_FOUND)
> @@ -885,6 +970,11 @@ riscv64_back_trace_cmd(struct bt_info *bt)
> if (riscv64_on_irq_stack(bt->tc->processor, bt->frameptr)) {
> riscv64_set_irq_stack(bt);
> bt->flags |= BT_IRQSTACK;
> + }
> +
> + if (riscv64_on_overflow_stack(bt->tc->processor, bt->frameptr)) {
> + riscv64_set_overflow_stack(bt);
> + bt->flags |= BT_OVERFLOW_STACK;
> }
>
> current.pc = bt->instptr;
> @@ -970,6 +1060,28 @@ riscv64_back_trace_cmd(struct bt_info *bt)
> }
> }
>
> + /* When backtracing to handle_kernel_stack_overflow()
> + * use pt_regs saved in overflow stack to continue
> + */
> +
> + if ((bt->flags & BT_OVERFLOW_STACK) &&
> + !riscv64_on_overflow_stack(bt->tc->processor, current.fp)) {
> +
> + overflow_regs = (struct riscv64_register *)
> + &bt->stackbuf[(ulong)(STACK_OFFSET_TYPE(current.sp))];
> +
> + riscv64_print_exception_frame(bt, current.sp, KERNEL_MODE);
> +
> + current.pc = overflow_regs->regs[RISCV64_REGS_EPC];
> + current.fp = overflow_regs->regs[RISCV64_REGS_FP];
> + current.sp = overflow_regs->regs[RISCV64_REGS_SP];
> +
> + riscv64_set_process_stack(bt);
> +
> + bt->flags &= ~BT_OVERFLOW_STACK;
> + fprintf(fp, "--- <OVERFLOW stack> ---\n");
> + }
> +
> if (CRASHDEBUG(8))
> fprintf(fp, "next %d pc %#lx sp %#lx fp %lx\n",
> level, current.pc, current.sp, current.fp);
> @@ -1582,6 +1694,7 @@ riscv64_init(int when)
> machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
>
> riscv64_irq_stack_init();
> + riscv64_overflow_stack_init();
> riscv64_stackframe_init();
> riscv64_page_type_init();
>
> @@ -1678,8 +1791,6 @@ riscv64_display_regs_from_elf_notes(int cpu, FILE *ofp)
> riscv64_dump_pt_regs(regs, ofp, 0);
> }
>
> -#define USER_MODE (0)
> -#define KERNEL_MODE (1)
>
> static void
> riscv64_print_exception_frame(struct bt_info *bt, ulong ptr, int mode)
--
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