[PATCH v4 17/25] AArch64: Report tag violation error information
Luis Machado
luis.machado@linaro.org
Wed Dec 30 15:39:08 GMT 2020
Updates on v4:
- Print exception error.
- Update function names.
--
Whenever a memory tag violation occurs, we get a SIGSEGV. Additional
information can be obtained through the siginfo data structure.
For AArch64 the Linux kernel may expose the fault address and tag
information, if we have a synchronous event. Otherwise there is
no fault address available.
The synchronous event looks like this:
--
(gdb) continue
Continuing.
Program received signal SIGSEGV, Segmentation fault
Memory tag violation while accessing address 0x0000fffff7ff8000
Allocation tag 0x1.
--
The asynchronous event looks like this:
--
(gdb) continue
Continuing.
Program received signal SIGSEGV, Segmentation fault
Memory tag violation
Fault address unavailable.
--
gdb/ChangeLog:
YYYY-MM-DD Luis Machado <luis.machado@linaro.org>
* aarch64-linux-tdep.c
(aarch64_linux_report_signal_info): New function.
(aarch64_linux_init_abi): Register
aarch64_linux_report_signal_info as the report_signal_info hook.
* arch/aarch64-linux.h (SEGV_MTEAERR): Define.
(SEGV_MTESERR): Define.
---
gdb/aarch64-linux-tdep.c | 66 ++++++++++++++++++++++++++++++++++++
gdb/arch/aarch64-mte-linux.h | 6 ++++
2 files changed, 72 insertions(+)
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index af43cf666a..1bdd127e0d 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -1702,6 +1702,69 @@ aarch64_linux_memtag_to_string (struct gdbarch *gdbarch,
return string_printf ("0x%s", phex_nz (tag, sizeof (tag)));
}
+/* AArch64 Linux implementation of the report_signal_info gdbarch
+ hook. Displays information about possible memory tag violations. */
+
+static void
+aarch64_linux_report_signal_info (struct gdbarch *gdbarch,
+ struct ui_out *uiout,
+ enum gdb_signal siggnal)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ if (!tdep->has_mte () || siggnal != GDB_SIGNAL_SEGV)
+ return;
+
+ CORE_ADDR fault_addr = 0;
+ long si_code = 0;
+
+ try
+ {
+ /* Sigcode tells us if the segfault is actually a memory tag
+ violation. */
+ si_code = parse_and_eval_long ("$_siginfo.si_code");
+
+ fault_addr
+ = parse_and_eval_long ("$_siginfo._sifields._sigfault.si_addr");
+ }
+ catch (const gdb_exception_error &exception)
+ {
+ exception_print (gdb_stderr, exception);
+ return;
+ }
+
+ /* If this is not a memory tag violation, just return. */
+ if (si_code != SEGV_MTEAERR && si_code != SEGV_MTESERR)
+ return;
+
+ uiout->text ("\n");
+
+ uiout->field_string ("sigcode-meaning", _("Memory tag violation"));
+
+ /* For synchronous faults, show additional information. */
+ if (si_code == SEGV_MTESERR)
+ {
+ uiout->text (_(" while accessing address "));
+ uiout->field_core_addr ("fault-addr", gdbarch, fault_addr);
+ uiout->text ("\n");
+
+ gdb::optional<CORE_ADDR> atag = aarch64_mte_get_atag (fault_addr);
+
+ if (!atag.has_value ())
+ uiout->text (_("Allocation tag unavailable"));
+ else
+ {
+ uiout->text (_("Allocation tag "));
+ uiout->field_string ("allocation-tag", hex_string (*atag));
+ }
+ }
+ else
+ {
+ uiout->text ("\n");
+ uiout->text (_("Fault address unavailable"));
+ }
+}
+
static void
aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -1782,6 +1845,9 @@ aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
/* Register a hook for converting a memory tag to a string. */
set_gdbarch_memtag_to_string (gdbarch, aarch64_linux_memtag_to_string);
+
+ set_gdbarch_report_signal_info (gdbarch,
+ aarch64_linux_report_signal_info);
}
/* Initialize the aarch64_linux_record_tdep. */
diff --git a/gdb/arch/aarch64-mte-linux.h b/gdb/arch/aarch64-mte-linux.h
index d44cae92a6..0f181a8595 100644
--- a/gdb/arch/aarch64-mte-linux.h
+++ b/gdb/arch/aarch64-mte-linux.h
@@ -35,6 +35,12 @@
#define AARCH64_MTE_LOGICAL_TAG_START_BIT 56
#define AARCH64_MTE_LOGICAL_MAX_VALUE 0xf
+/* Memory tagging definitions. */
+#ifndef SEGV_MTEAERR
+# define SEGV_MTEAERR 8
+# define SEGV_MTESERR 9
+#endif
+
/* Memory tag types for AArch64. */
enum class aarch64_memtag_type
{
--
2.25.1
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