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arm64: add cpu context registers to better support gdb stack unwind
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Let gdb fetch_registers include cpu context registers x19~x28, which
will be helpful to show more args when gdb stack unwind.

Without the patch:
    crash> gdb bt
    #0  __switch_to (prev=<unavailable>, prev@entry=0xffffff80025f0000, next=next@entry=<unavailable>) at arch/arm64/kernel/process.c:566
    #1  0xffffffc008f820b8 in context_switch (rq=0xffffff81fcf419c0, prev=0xffffff80025f0000, next=<unavailable>, rf=<optimized out>) at kernel/sched/core.c:5471
    #2  __schedule (sched_mode=<optimized out>, sched_mode@entry=168999904) at kernel/sched/core.c:6857
    #3  0xffffffc008f82514 in schedule () at kernel/sched/core.c:6933
    ...

With the patch:
    crash> gdb bt
    #0  __switch_to (prev=prev@entry=0xffffff80025f0000, next=next@entry=0xffffff80026092c0) at arch/arm64/kernel/process.c:566
    #1  0xffffffc008f820b8 in context_switch (rq=0xffffff81fcf419c0, prev=0xffffff80025f0000, next=0xffffff80026092c0, rf=<optimized out>) at kernel/sched/core.c:5471
    #2  __schedule (sched_mode=<optimized out>, sched_mode@entry=168999904) at kernel/sched/core.c:6857
    #3  0xffffffc008f82514 in schedule () at kernel/sched/core.c:6933
    ...

Signed-off-by: Guanyou.Chen <[email protected]>
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@lian-bo
Guanyou.Chen authored and lian-bo committed Dec 11, 2024
1 parent aa9f724 commit f070329
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Showing 3 changed files with 110 additions and 8 deletions.
66 changes: 64 additions & 2 deletions arm64.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2725,6 +2725,9 @@ arm64_stackframe_init(void)
long task_struct_thread;
long thread_struct_cpu_context;
long context_sp, context_pc, context_fp;
long context_x19, context_x20, context_x21, context_x22;
long context_x23, context_x24, context_x25, context_x26;
long context_x27, context_x28;
struct syment *sp1, *sp1n, *sp2, *sp2n, *sp3, *sp3n;

STRUCT_SIZE_INIT(note_buf, "note_buf_t");
Expand Down Expand Up @@ -2809,6 +2812,16 @@ arm64_stackframe_init(void)
context_sp = MEMBER_OFFSET("cpu_context", "sp");
context_fp = MEMBER_OFFSET("cpu_context", "fp");
context_pc = MEMBER_OFFSET("cpu_context", "pc");
context_x19 = MEMBER_OFFSET("cpu_context", "x19");
context_x20 = MEMBER_OFFSET("cpu_context", "x20");
context_x21 = MEMBER_OFFSET("cpu_context", "x21");
context_x22 = MEMBER_OFFSET("cpu_context", "x22");
context_x23 = MEMBER_OFFSET("cpu_context", "x23");
context_x24 = MEMBER_OFFSET("cpu_context", "x24");
context_x25 = MEMBER_OFFSET("cpu_context", "x25");
context_x26 = MEMBER_OFFSET("cpu_context", "x26");
context_x27 = MEMBER_OFFSET("cpu_context", "x27");
context_x28 = MEMBER_OFFSET("cpu_context", "x28");
if (context_sp == INVALID_OFFSET) {
error(INFO, "cannot determine cpu_context.sp offset\n");
return;
Expand All @@ -2827,6 +2840,26 @@ arm64_stackframe_init(void)
task_struct_thread + thread_struct_cpu_context + context_fp;
ASSIGN_OFFSET(task_struct_thread_context_pc) =
task_struct_thread + thread_struct_cpu_context + context_pc;
ASSIGN_OFFSET(task_struct_thread_context_x19) =
task_struct_thread + thread_struct_cpu_context + context_x19;
ASSIGN_OFFSET(task_struct_thread_context_x20) =
task_struct_thread + thread_struct_cpu_context + context_x20;
ASSIGN_OFFSET(task_struct_thread_context_x21) =
task_struct_thread + thread_struct_cpu_context + context_x21;
ASSIGN_OFFSET(task_struct_thread_context_x22) =
task_struct_thread + thread_struct_cpu_context + context_x22;
ASSIGN_OFFSET(task_struct_thread_context_x23) =
task_struct_thread + thread_struct_cpu_context + context_x23;
ASSIGN_OFFSET(task_struct_thread_context_x24) =
task_struct_thread + thread_struct_cpu_context + context_x24;
ASSIGN_OFFSET(task_struct_thread_context_x25) =
task_struct_thread + thread_struct_cpu_context + context_x25;
ASSIGN_OFFSET(task_struct_thread_context_x26) =
task_struct_thread + thread_struct_cpu_context + context_x26;
ASSIGN_OFFSET(task_struct_thread_context_x27) =
task_struct_thread + thread_struct_cpu_context + context_x27;
ASSIGN_OFFSET(task_struct_thread_context_x28) =
task_struct_thread + thread_struct_cpu_context + context_x28;
}

#define KERNEL_MODE (1)
Expand Down Expand Up @@ -4251,6 +4284,16 @@ arm64_get_stackframe(struct bt_info *bt, struct arm64_stackframe *frame)
frame->sp = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_sp));
frame->pc = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_pc));
frame->fp = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_fp));
frame->x19 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x19));
frame->x20 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x20));
frame->x21 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x21));
frame->x22 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x22));
frame->x23 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x23));
frame->x24 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x24));
frame->x25 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x25));
frame->x26 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x26));
frame->x27 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x27));
frame->x28 = ULONG(tt->task_struct + OFFSET(task_struct_thread_context_x28));

return TRUE;
}
Expand All @@ -4275,10 +4318,29 @@ arm64_get_stack_frame(struct bt_info *bt, ulong *pcp, ulong *spp)
ur_bitmap->ur.pc = stackframe.pc;
ur_bitmap->ur.sp = stackframe.sp;
ur_bitmap->ur.regs[29] = stackframe.fp;
ur_bitmap->ur.regs[28] = stackframe.x28;
ur_bitmap->ur.regs[27] = stackframe.x27;
ur_bitmap->ur.regs[26] = stackframe.x26;
ur_bitmap->ur.regs[25] = stackframe.x25;
ur_bitmap->ur.regs[24] = stackframe.x24;
ur_bitmap->ur.regs[23] = stackframe.x23;
ur_bitmap->ur.regs[22] = stackframe.x22;
ur_bitmap->ur.regs[21] = stackframe.x21;
ur_bitmap->ur.regs[20] = stackframe.x20;
ur_bitmap->ur.regs[19] = stackframe.x19;
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, pc));
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, sp));
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0])
+ X29_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X29_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X28_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X27_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X26_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X25_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X24_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X23_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X22_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X21_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X20_REGNUM - X0_REGNUM);
SET_BIT(ur_bitmap->bitmap, REG_SEQ(arm64_pt_regs, regs[0]) + X19_REGNUM - X0_REGNUM);
bt->machdep = ur_bitmap;
bt->need_free = TRUE;
}
Expand Down
20 changes: 20 additions & 0 deletions defs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2259,6 +2259,16 @@ struct offset_table { /* stash of commonly-used offsets */
long thread_struct_gsbase;
long thread_struct_fs;
long thread_struct_gs;
long task_struct_thread_context_x19;
long task_struct_thread_context_x20;
long task_struct_thread_context_x21;
long task_struct_thread_context_x22;
long task_struct_thread_context_x23;
long task_struct_thread_context_x24;
long task_struct_thread_context_x25;
long task_struct_thread_context_x26;
long task_struct_thread_context_x27;
long task_struct_thread_context_x28;
};

struct size_table { /* stash of commonly-used sizes */
Expand Down Expand Up @@ -3584,6 +3594,16 @@ struct machine_specific {
};

struct arm64_stackframe {
unsigned long x19;
unsigned long x20;
unsigned long x21;
unsigned long x22;
unsigned long x23;
unsigned long x24;
unsigned long x25;
unsigned long x26;
unsigned long x27;
unsigned long x28;
unsigned long fp;
unsigned long sp;
unsigned long pc;
Expand Down
32 changes: 26 additions & 6 deletions symbols.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9832,12 +9832,32 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(task_struct_thread_reg29));
fprintf(fp, " task_struct_thread_reg31: %ld\n",
OFFSET(task_struct_thread_reg31));
fprintf(fp, " task_struct_thread_context_fp: %ld\n",
OFFSET(task_struct_thread_context_fp));
fprintf(fp, " task_struct_thread_context_sp: %ld\n",
OFFSET(task_struct_thread_context_sp));
fprintf(fp, " task_struct_thread_context_pc: %ld\n",
OFFSET(task_struct_thread_context_pc));
fprintf(fp, "task_struct_thread_context_x19: %ld\n",
OFFSET(task_struct_thread_context_x19));
fprintf(fp, "task_struct_thread_context_x20: %ld\n",
OFFSET(task_struct_thread_context_x20));
fprintf(fp, "task_struct_thread_context_x21: %ld\n",
OFFSET(task_struct_thread_context_x21));
fprintf(fp, "task_struct_thread_context_x22: %ld\n",
OFFSET(task_struct_thread_context_x22));
fprintf(fp, "task_struct_thread_context_x23: %ld\n",
OFFSET(task_struct_thread_context_x23));
fprintf(fp, "task_struct_thread_context_x24: %ld\n",
OFFSET(task_struct_thread_context_x24));
fprintf(fp, "task_struct_thread_context_x25: %ld\n",
OFFSET(task_struct_thread_context_x25));
fprintf(fp, "task_struct_thread_context_x26: %ld\n",
OFFSET(task_struct_thread_context_x26));
fprintf(fp, "task_struct_thread_context_x27: %ld\n",
OFFSET(task_struct_thread_context_x27));
fprintf(fp, "task_struct_thread_context_x28: %ld\n",
OFFSET(task_struct_thread_context_x28));
fprintf(fp, " task_struct_thread_context_fp: %ld\n",
OFFSET(task_struct_thread_context_fp));
fprintf(fp, " task_struct_thread_context_sp: %ld\n",
OFFSET(task_struct_thread_context_sp));
fprintf(fp, " task_struct_thread_context_pc: %ld\n",
OFFSET(task_struct_thread_context_pc));
fprintf(fp, " task_struct_processor: %ld\n",
OFFSET(task_struct_processor));
fprintf(fp, " task_struct_p_pptr: %ld\n",
Expand Down

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