From: "Torbjörn SVENSSON via Gdb-patches" <gdb-patches@sourceware.org>
To: <gdb-patches@sourceware.org>
Subject: [PATCH v2] gdb/arm: Stop unwinding on error, but do not assert
Date: Thu, 13 Oct 2022 11:17:41 +0200 [thread overview]
Message-ID: <20221013091740.645783-1-torbjorn.svensson@foss.st.com> (raw)
When it's impossible to read the FPCCR and XPSR, the unwinding is
unpredictable as the it's not possible to determine the correct
frame size or padding.
The only sane thing to do in this condition is to stop the unwinding.
Without this patch, gdb would assert if this errornous state was
detected.
Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
---
gdb/arm-tdep.c | 35 +++++++++++++++++++++++++++++------
1 file changed, 29 insertions(+), 6 deletions(-)
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 041e6afefed..afcbce478c2 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -3591,9 +3591,13 @@ arm_m_exception_cache (frame_info_ptr this_frame)
ULONGEST fpcar;
/* Read FPCCR register. */
- gdb_assert (safe_read_memory_unsigned_integer (FPCCR,
- ARM_INT_REGISTER_SIZE,
- byte_order, &fpccr));
+ if (!safe_read_memory_unsigned_integer (FPCCR, ARM_INT_REGISTER_SIZE,
+ byte_order, &fpccr))
+ {
+ warning (_("Could not fetch required FPCCR content. Further "
+ "unwind is impossible."));
+ return NULL;
+ }
/* Read FPCAR register. */
if (!safe_read_memory_unsigned_integer (FPCAR, ARM_INT_REGISTER_SIZE,
@@ -3669,9 +3673,15 @@ arm_m_exception_cache (frame_info_ptr this_frame)
aligner between the top of the 32-byte stack frame and the
previous context's stack pointer. */
ULONGEST xpsr;
- gdb_assert (safe_read_memory_unsigned_integer (cache->saved_regs[
- ARM_PS_REGNUM].addr (), 4,
- byte_order, &xpsr));
+ if (!safe_read_memory_unsigned_integer (cache->saved_regs[ARM_PS_REGNUM]
+ .addr (), ARM_INT_REGISTER_SIZE,
+ byte_order, &xpsr))
+ {
+ warning (_("Could not fetch required XPSR content. Further unwind "
+ "is impossible."));
+ return NULL;
+ }
+
if (bit (xpsr, 9) != 0)
{
CORE_ADDR new_sp = arm_cache_get_prev_sp_value (cache, tdep) + 4;
@@ -3703,6 +3713,14 @@ arm_m_exception_this_id (frame_info_ptr this_frame,
*this_cache = arm_m_exception_cache (this_frame);
cache = (struct arm_prologue_cache *) *this_cache;
+ /* Unwind of this frame is not possible. Return outer_frame_id to stop the
+ unwinding. */
+ if (cache == NULL)
+ {
+ *this_id = outer_frame_id;
+ return;
+ }
+
/* Our frame ID for a stub frame is the current SP and LR. */
arm_gdbarch_tdep *tdep
= gdbarch_tdep<arm_gdbarch_tdep> (get_frame_arch (this_frame));
@@ -3725,6 +3743,11 @@ arm_m_exception_prev_register (frame_info_ptr this_frame,
*this_cache = arm_m_exception_cache (this_frame);
cache = (struct arm_prologue_cache *) *this_cache;
+ /* It's not allowed to call prev_register when this_id has returned the
+ outer_frame_id. The arm_m_exception_cache function will return NULL when
+ the frame cannot be properly unwinded. */
+ gdb_assert (cache != NULL);
+
/* The value was already reconstructed into PREV_SP. */
arm_gdbarch_tdep *tdep
= gdbarch_tdep<arm_gdbarch_tdep> (get_frame_arch (this_frame));
--
2.25.1
next reply other threads:[~2022-10-13 9:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-13 9:17 Torbjörn SVENSSON via Gdb-patches [this message]
2022-10-13 9:46 ` Luis Machado via Gdb-patches
2022-10-13 11:21 ` Pedro Alves
2022-10-13 12:24 ` Torbjorn SVENSSON via Gdb-patches
2022-10-13 13:25 ` Pedro Alves
2022-10-13 13:11 ` Luis Machado via Gdb-patches
2022-10-13 13:41 ` Pedro Alves
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