3:49 a.m.
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(a)tinylab.org>
---
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)
/*
* 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)
--
2.20.1