380 lines
13 KiB
Diff
380 lines
13 KiB
Diff
From 995db8ab88916b6397676b67be98c0a4f82cca49 Mon Sep 17 00:00:00 2001
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From: Hong YANG <hong.yang3@nio.com>
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Date: Mon, 15 Nov 2021 15:41:01 +0800
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Subject: [PATCH 1/3] arm64: Support overflow stack panic
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Kernel commit <872d8327ce89> ("arm64: add VMAP_STACK overflow detection")
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has supported the overflow stack exception handling. Without the patch, the
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"bt" command will make crash generate a core dump because of segmentation
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fault. With the patch, the "bt" command can display the overflow stack.
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Before:
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crash> bt
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PID: 3607 TASK: ffffffcbf9a4da00 CPU: 2 COMMAND: "sh"
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Segmentation fault (core dumped)
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After:
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crash> bt
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PID: 3607 TASK: ffffffcbf9a4da00 CPU: 2 COMMAND: "sh"
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#0 [ffffffccbfd85f50] __delay at ffffff8008ceded8
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...
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#5 [ffffffccbfd85fd0] emergency_restart at ffffff80080d49fc
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#6 [ffffffccbfd86140] panic at ffffff80080af4c0
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#7 [ffffffccbfd86150] nmi_panic at ffffff80080af150
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#8 [ffffffccbfd86190] handle_bad_stack at ffffff800808b0b8
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#9 [ffffffccbfd862d0] __bad_stack at ffffff800808285c
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PC: ffffff8008082e80 [el1_sync]
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LR: ffffff8000d6c214 [stack_overflow_demo+84]
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SP: ffffff1a79930070 PSTATE: 204003c5
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X29: ffffff8011b03d00 X28: ffffffcbf9a4da00 X27: ffffff8008e02000
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X26: 0000000000000040 X25: 0000000000000124 X24: ffffffcbf9a4da00
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X23: 0000007daec2e288 X22: ffffffcbfe03b800 X21: 0000007daec2e288
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X20: 0000000000000002 X19: 0000000000000002 X18: 0000000000000002
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X17: 00000000000003e7 X16: 0000000000000000 X15: 0000000000000000
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X14: ffffffcc17facb00 X13: ffffffccb4c25c00 X12: 0000000000000000
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X11: ffffffcc17fad660 X10: 0000000000000af0 X9: 0000000000000000
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X8: ffffff1a799334f0 X7: 0000000000000000 X6: 000000000000003f
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X5: 0000000000000040 X4: 0000000000000010 X3: 00000065981d07f0
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X2: 00000065981d07f0 X1: 0000000000000000 X0: ffffff1a799334f0
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Signed-off-by: Hong YANG <hong.yang3@nio.com>
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---
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arm64.c | 169 ++++++++++++++++++++++++++++++++++++++++++++++++++------
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defs.h | 6 ++
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2 files changed, 159 insertions(+), 16 deletions(-)
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diff --git a/arm64.c b/arm64.c
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index 94681d1a37db..23c3d75d85aa 100644
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--- a/arm64.c
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+++ b/arm64.c
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@@ -45,6 +45,7 @@ static int arm64_vtop_3level_4k(ulong, ulong, physaddr_t *, int);
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static int arm64_vtop_4level_4k(ulong, ulong, physaddr_t *, int);
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static ulong arm64_get_task_pgd(ulong);
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static void arm64_irq_stack_init(void);
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+static void arm64_overflow_stack_init(void);
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static void arm64_stackframe_init(void);
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static int arm64_eframe_search(struct bt_info *);
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static int arm64_is_kernel_exception_frame(struct bt_info *, ulong);
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@@ -63,6 +64,7 @@ static int arm64_get_dumpfile_stackframe(struct bt_info *, struct arm64_stackfra
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static int arm64_in_kdump_text(struct bt_info *, struct arm64_stackframe *);
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static int arm64_in_kdump_text_on_irq_stack(struct bt_info *);
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static int arm64_switch_stack(struct bt_info *, struct arm64_stackframe *, FILE *);
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+static int arm64_switch_stack_from_overflow(struct bt_info *, struct arm64_stackframe *, FILE *);
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static int arm64_get_stackframe(struct bt_info *, struct arm64_stackframe *);
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static void arm64_get_stack_frame(struct bt_info *, ulong *, ulong *);
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static void arm64_gen_hidden_frame(struct bt_info *bt, ulong, struct arm64_stackframe *);
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@@ -78,8 +80,11 @@ static int arm64_get_smp_cpus(void);
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static void arm64_clear_machdep_cache(void);
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static int arm64_on_process_stack(struct bt_info *, ulong);
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static int arm64_in_alternate_stack(int, ulong);
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+static int arm64_in_alternate_stackv(int cpu, ulong stkptr, ulong *stacks, ulong stack_size);
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static int arm64_on_irq_stack(int, ulong);
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+static int arm64_on_overflow_stack(int, ulong);
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static void arm64_set_irq_stack(struct bt_info *);
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+static void arm64_set_overflow_stack(struct bt_info *);
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static void arm64_set_process_stack(struct bt_info *);
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static int arm64_get_kvaddr_ranges(struct vaddr_range *);
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static void arm64_get_crash_notes(void);
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@@ -463,6 +468,7 @@ arm64_init(int when)
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machdep->hz = 100;
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arm64_irq_stack_init();
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+ arm64_overflow_stack_init();
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arm64_stackframe_init();
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break;
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@@ -1715,6 +1721,49 @@ arm64_irq_stack_init(void)
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}
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}
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+/*
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+ * Gather Overflow stack values.
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+ *
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+ * Overflow stack supported since 4.14, in commit 872d8327c
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+ */
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+static void
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+arm64_overflow_stack_init(void)
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+{
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+ int i;
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+ struct syment *sp;
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+ struct gnu_request request, *req;
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+ struct machine_specific *ms = machdep->machspec;
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+ req = &request;
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+
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+ if (symbol_exists("overflow_stack") &&
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+ (sp = per_cpu_symbol_search("overflow_stack")) &&
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+ get_symbol_type("overflow_stack", NULL, req)) {
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+ if (CRASHDEBUG(1)) {
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+ fprintf(fp, "overflow_stack: \n");
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+ fprintf(fp, " type: %x, %s\n",
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+ (int)req->typecode,
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+ (req->typecode == TYPE_CODE_ARRAY) ?
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+ "TYPE_CODE_ARRAY" : "other");
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+ fprintf(fp, " target_typecode: %x, %s\n",
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+ (int)req->target_typecode,
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+ req->target_typecode == TYPE_CODE_INT ?
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+ "TYPE_CODE_INT" : "other");
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+ fprintf(fp, " target_length: %ld\n",
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+ req->target_length);
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+ fprintf(fp, " length: %ld\n", req->length);
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+ }
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+
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+ if (!(ms->overflow_stacks = (ulong *)malloc((size_t)(kt->cpus * sizeof(ulong)))))
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+ error(FATAL, "cannot malloc overflow_stack addresses\n");
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+
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+ ms->overflow_stack_size = ARM64_OVERFLOW_STACK_SIZE;
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+ machdep->flags |= OVERFLOW_STACKS;
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+
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+ for (i = 0; i < kt->cpus; i++)
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+ ms->overflow_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
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+ }
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+}
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+
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/*
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* Gather and verify all of the backtrace requirements.
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*/
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@@ -1960,6 +2009,7 @@ static char *arm64_exception_functions[] = {
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"do_mem_abort",
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"do_el0_irq_bp_hardening",
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"do_sp_pc_abort",
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+ "handle_bad_stack",
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NULL
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};
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@@ -1978,7 +2028,10 @@ arm64_in_exception_text(ulong ptr)
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if ((ptr >= ms->__exception_text_start) &&
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(ptr < ms->__exception_text_end))
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return TRUE;
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- } else if ((name = closest_symbol(ptr))) { /* Linux 5.5 and later */
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+ }
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+
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+ name = closest_symbol(ptr);
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+ if (name != NULL) { /* Linux 5.5 and later */
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for (func = &arm64_exception_functions[0]; *func; func++) {
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if (STREQ(name, *func))
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return TRUE;
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@@ -2252,15 +2305,14 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
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if ((frame->fp == 0) && (frame->pc == 0))
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return FALSE;
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- if (!(machdep->flags & IRQ_STACKS))
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- return TRUE;
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-
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- if (!(machdep->flags & IRQ_STACKS))
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+ if (!(machdep->flags & (IRQ_STACKS | OVERFLOW_STACKS)))
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return TRUE;
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if (machdep->flags & UNW_4_14) {
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- if ((bt->flags & BT_IRQSTACK) &&
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- !arm64_on_irq_stack(bt->tc->processor, frame->fp)) {
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+ if (((bt->flags & BT_IRQSTACK) &&
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+ !arm64_on_irq_stack(bt->tc->processor, frame->fp)) ||
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+ ((bt->flags & BT_OVERFLOW_STACK) &&
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+ !arm64_on_overflow_stack(bt->tc->processor, frame->fp))) {
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if (arm64_on_process_stack(bt, frame->fp)) {
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arm64_set_process_stack(bt);
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@@ -2677,6 +2729,9 @@ arm64_back_trace_cmd(struct bt_info *bt)
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if (arm64_on_irq_stack(bt->tc->processor, bt->frameptr)) {
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arm64_set_irq_stack(bt);
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bt->flags |= BT_IRQSTACK;
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+ } else if (arm64_on_overflow_stack(bt->tc->processor, bt->frameptr)) {
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+ arm64_set_overflow_stack(bt);
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+ bt->flags |= BT_OVERFLOW_STACK;
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}
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stackframe.sp = bt->stkptr;
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stackframe.pc = bt->instptr;
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@@ -2731,7 +2786,9 @@ arm64_back_trace_cmd(struct bt_info *bt)
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break;
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if (arm64_in_exception_text(bt->instptr) && INSTACK(stackframe.fp, bt)) {
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- if (!(bt->flags & BT_IRQSTACK) ||
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+ if (bt->flags & BT_OVERFLOW_STACK) {
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+ exception_frame = stackframe.fp - KERN_EFRAME_OFFSET;
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+ } else if (!(bt->flags & BT_IRQSTACK) ||
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((stackframe.sp + SIZE(pt_regs)) < bt->stacktop)) {
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if (arm64_is_kernel_exception_frame(bt, stackframe.fp - KERN_EFRAME_OFFSET))
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exception_frame = stackframe.fp - KERN_EFRAME_OFFSET;
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@@ -2745,6 +2802,12 @@ arm64_back_trace_cmd(struct bt_info *bt)
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break;
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}
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+ if ((bt->flags & BT_OVERFLOW_STACK) &&
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+ !arm64_on_overflow_stack(bt->tc->processor, stackframe.fp)) {
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+ bt->flags &= ~BT_OVERFLOW_STACK;
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+ if (arm64_switch_stack_from_overflow(bt, &stackframe, ofp) == USER_MODE)
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+ break;
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+ }
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level++;
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}
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@@ -3131,6 +3194,43 @@ arm64_switch_stack(struct bt_info *bt, struct arm64_stackframe *frame, FILE *ofp
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return KERNEL_MODE;
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}
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+static int
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+arm64_switch_stack_from_overflow(struct bt_info *bt, struct arm64_stackframe *frame, FILE *ofp)
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+{
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+ int i;
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+ ulong stacktop, words, addr;
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+ ulong *stackbuf;
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+ char buf[BUFSIZE];
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+ struct machine_specific *ms = machdep->machspec;
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+
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+ if (bt->flags & BT_FULL) {
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+ stacktop = ms->overflow_stacks[bt->tc->processor] + ms->overflow_stack_size;
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+ words = (stacktop - bt->bptr) / sizeof(ulong);
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+ stackbuf = (ulong *)GETBUF(words * sizeof(ulong));
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+ readmem(bt->bptr, KVADDR, stackbuf, words * sizeof(long),
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+ "top of overflow stack", FAULT_ON_ERROR);
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+
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+ addr = bt->bptr;
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+ for (i = 0; i < words; i++) {
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+ if (!(i & 1))
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+ fprintf(ofp, "%s %lx: ", i ? "\n" : "", addr);
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+ fprintf(ofp, "%s ", format_stack_entry(bt, buf, stackbuf[i], 0));
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+ addr += sizeof(ulong);
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+ }
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+ fprintf(ofp, "\n");
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+ FREEBUF(stackbuf);
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+ }
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+ fprintf(ofp, "--- <Overflow stack> ---\n");
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+
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+ if (frame->fp == 0)
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+ return USER_MODE;
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+
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+ if (!(machdep->flags & UNW_4_14))
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+ arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
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+
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+ return KERNEL_MODE;
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+}
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+
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static int
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arm64_get_dumpfile_stackframe(struct bt_info *bt, struct arm64_stackframe *frame)
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{
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@@ -3682,6 +3782,16 @@ arm64_display_machine_stats(void)
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machdep->machspec->irq_stacks[i]);
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}
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}
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+ if (machdep->machspec->overflow_stack_size) {
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+ fprintf(fp, "OVERFLOW STACK SIZE: %ld\n",
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+ machdep->machspec->overflow_stack_size);
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+ fprintf(fp, " OVERFLOW STACKS:\n");
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+ for (i = 0; i < kt->cpus; i++) {
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+ pad = (i < 10) ? 3 : (i < 100) ? 2 : (i < 1000) ? 1 : 0;
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+ fprintf(fp, "%s CPU %d: %lx\n", space(pad), i,
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+ machdep->machspec->overflow_stacks[i]);
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+ }
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+ }
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}
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static int
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@@ -3875,24 +3985,41 @@ arm64_on_process_stack(struct bt_info *bt, ulong stkptr)
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}
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static int
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-arm64_on_irq_stack(int cpu, ulong stkptr)
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+arm64_in_alternate_stackv(int cpu, ulong stkptr, ulong *stacks, ulong stack_size)
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{
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- return arm64_in_alternate_stack(cpu, stkptr);
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+ if ((cpu >= kt->cpus) || (stacks == NULL) || !stack_size)
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+ return FALSE;
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+
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+ if ((stkptr >= stacks[cpu]) &&
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+ (stkptr < (stacks[cpu] + stack_size)))
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+ return TRUE;
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+
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+ return FALSE;
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}
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static int
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arm64_in_alternate_stack(int cpu, ulong stkptr)
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+{
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+ return (arm64_on_irq_stack(cpu, stkptr) ||
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+ arm64_on_overflow_stack(cpu, stkptr));
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+}
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+
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+static int
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+arm64_on_irq_stack(int cpu, ulong stkptr)
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{
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struct machine_specific *ms = machdep->machspec;
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- if (!ms->irq_stack_size || (cpu >= kt->cpus))
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- return FALSE;
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+ return arm64_in_alternate_stackv(cpu, stkptr,
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+ ms->irq_stacks, ms->irq_stack_size);
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+}
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- if ((stkptr >= ms->irq_stacks[cpu]) &&
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- (stkptr < (ms->irq_stacks[cpu] + ms->irq_stack_size)))
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- return TRUE;
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+static int
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+arm64_on_overflow_stack(int cpu, ulong stkptr)
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+{
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+ struct machine_specific *ms = machdep->machspec;
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- return FALSE;
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+ return arm64_in_alternate_stackv(cpu, stkptr,
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+ ms->overflow_stacks, ms->overflow_stack_size);
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}
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static void
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@@ -3905,6 +4032,16 @@ arm64_set_irq_stack(struct bt_info *bt)
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alter_stackbuf(bt);
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}
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+static void
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+arm64_set_overflow_stack(struct bt_info *bt)
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+{
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+ struct machine_specific *ms = machdep->machspec;
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+
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+ bt->stackbase = ms->overflow_stacks[bt->tc->processor];
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+ bt->stacktop = bt->stackbase + ms->overflow_stack_size;
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+ alter_stackbuf(bt);
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+}
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+
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static void
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arm64_set_process_stack(struct bt_info *bt)
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{
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diff --git a/defs.h b/defs.h
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index a2f30853a4b1..7e2a16e34a59 100644
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--- a/defs.h
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+++ b/defs.h
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@@ -3218,6 +3218,7 @@ typedef signed int s32;
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#define UNW_4_14 (0x200)
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#define FLIPPED_VM (0x400)
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#define HAS_PHYSVIRT_OFFSET (0x800)
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+#define OVERFLOW_STACKS (0x1000)
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/*
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* Get kimage_voffset from /dev/crash
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@@ -3260,6 +3261,7 @@ typedef signed int s32;
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#define ARM64_STACK_SIZE (16384)
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#define ARM64_IRQ_STACK_SIZE ARM64_STACK_SIZE
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+#define ARM64_OVERFLOW_STACK_SIZE (4096)
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#define _SECTION_SIZE_BITS 30
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#define _SECTION_SIZE_BITS_5_12 27
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@@ -3332,6 +3334,9 @@ struct machine_specific {
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char *irq_stackbuf;
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ulong __irqentry_text_start;
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ulong __irqentry_text_end;
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+ ulong overflow_stack_size;
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+ ulong *overflow_stacks;
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+ char *overflow_stackbuf;
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/* for exception vector code */
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ulong exp_entry1_start;
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ulong exp_entry1_end;
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@@ -5770,6 +5775,7 @@ ulong cpu_map_addr(const char *type);
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#define BT_CPUMASK (0x1000000000000ULL)
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#define BT_SHOW_ALL_REGS (0x2000000000000ULL)
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#define BT_REGS_NOT_FOUND (0x4000000000000ULL)
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+#define BT_OVERFLOW_STACK (0x8000000000000ULL)
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#define BT_SYMBOL_OFFSET (BT_SYMBOLIC_ARGS)
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#define BT_REF_HEXVAL (0x1)
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--
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2.20.1
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