From: Ard Biesheuvel <ardb@kernel.org>
To: linux@armlinux.org.uk
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Kees Cook <keescook@chromium.org>,
Keith Packard <keithpac@amazon.com>,
Linus Walleij <linus.walleij@linaro.org>
Subject: [PATCH 07/10] ARM: unwind: dump exception stack from calling frame
Date: Tue, 21 Sep 2021 11:54:05 +0200 [thread overview]
Message-ID: <20210921095408.133210-8-ardb@kernel.org> (raw)
In-Reply-To: <20210921095408.133210-1-ardb@kernel.org>
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>
---
arch/arm/include/asm/stacktrace.h | 11 +++++++++++
arch/arm/kernel/traps.c | 3 ++-
arch/arm/kernel/unwind.c | 8 +++++++-
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
index e86f55155500..8dcad8156561 100644
--- a/arch/arm/include/asm/stacktrace.h
+++ b/arch/arm/include/asm/stacktrace.h
@@ -13,6 +13,17 @@ struct stackframe {
unsigned long sp;
unsigned long lr;
unsigned long pc;
+
+#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);
}
}
--
2.30.2
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next prev parent reply other threads:[~2021-09-21 9:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 9:53 [PATCH 00/10] ARM: add support for IRQ stacks Ard Biesheuvel
2021-09-21 9:53 ` [PATCH 01/10] ARM: fix incorrect use of get_kernel_nofault() Ard Biesheuvel
2021-09-21 10:39 ` Arnd Bergmann
2021-09-21 14:02 ` Russell King (Oracle)
2021-09-21 14:33 ` Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 02/10] ARM: remove some dead code Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 03/10] ARM: assembler: introduce bl_r and bl_m macros Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 04/10] ARM: optimize indirect call to handle_arch_irq for v7 cores Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 05/10] ARM: unwind: support unwinding across multiple stacks Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 06/10] ARM: export dump_mem() to other objects Ard Biesheuvel
2021-09-21 9:54 ` Ard Biesheuvel [this message]
2021-09-21 9:54 ` [PATCH 08/10] ARM: implement IRQ stacks Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 09/10] ARM: call_with_stack: add unwind support Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 10/10] ARM: run softirqs on the per-CPU IRQ stack Ard Biesheuvel
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