aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorArd Biesheuvel2021-10-05 09:15:39 +0200
committerArd Biesheuvel2021-12-03 15:11:31 +0100
commit4ab6827081c63b83011a18d8e27f621ed34b1194 (patch)
treec47ae449b8c9cb2343f187c1b27993c953c54298
parent8cdfdf7fe4fec5a952edfb8927ee7cc639c58184 (diff)
ARM: unwind: dump exception stack from calling frame
The existing code that dumps the contents of the pt_regs structure passed to __entry routines does so while unwinding the callee frame, and dereferences the stack pointer as a struct pt_regs*. This will no longer work when we enable support for IRQ or overflow stacks, because the struct pt_regs may live on the task stack, while we are executing from another stack. The unwinder has access to this information, but only while unwinding the calling frame. So let's combine the exception stack dumping code with the handling of the calling frame as well. By printing it before dumping the caller/callee addresses, the output order is preserved. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Linus Walleij <linus.walleij@linaro.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
-rw-r--r--arch/arm/include/asm/stacktrace.h10
-rw-r--r--arch/arm/kernel/traps.c3
-rw-r--r--arch/arm/kernel/unwind.c8
3 files changed, 19 insertions, 2 deletions
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
index 33ee1aa4b8c0..d87d60532b86 100644
--- a/arch/arm/include/asm/stacktrace.h
+++ b/arch/arm/include/asm/stacktrace.h
@@ -18,6 +18,16 @@ struct stackframe {
struct llist_node *kr_cur;
struct task_struct *tsk;
#endif
+#ifdef CONFIG_ARM_UNWIND
+ /*
+ * This field is used to track the stack pointer value when calling
+ * __entry routines. This is needed when IRQ stacks and overflow stacks
+ * are used, because in that case, the struct pt_regs passed to these
+ * __entry routines may be at the top of the task stack, while we are
+ * executing from another stack.
+ */
+ unsigned long sp_low;
+#endif
};
static __always_inline
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index e4698605bb72..89be21ec3b52 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -74,7 +74,8 @@ void dump_backtrace_entry(unsigned long where, unsigned long from,
loglvl, where, from);
#endif
- if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
+ if (!IS_ENABLED(CONFIG_UNWINDER_ARM) &&
+ in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
dump_mem(loglvl, "Exception stack", frame + 4, end);
}
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 9cb9af3fc433..b7a6141c342f 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -29,6 +29,7 @@
#include <linux/spinlock.h>
#include <linux/list.h>
+#include <asm/sections.h>
#include <asm/stacktrace.h>
#include <asm/traps.h>
#include <asm/unwind.h>
@@ -459,6 +460,7 @@ int unwind_frame(struct stackframe *frame)
frame->sp = ctrl.vrs[SP];
frame->lr = ctrl.vrs[LR];
frame->pc = ctrl.vrs[PC];
+ frame->sp_low = ctrl.sp_low;
return URC_OK;
}
@@ -502,7 +504,11 @@ void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
urc = unwind_frame(&frame);
if (urc < 0)
break;
- dump_backtrace_entry(where, frame.pc, frame.sp - 4, loglvl);
+ if (in_entry_text(where))
+ dump_mem(loglvl, "Exception stack", frame.sp_low,
+ frame.sp_low + sizeof(struct pt_regs));
+
+ dump_backtrace_entry(where, frame.pc, 0, loglvl);
}
}