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AArch64: Report tag violation error information

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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 0x0500fffff7ff8000
Allocation tag 0x1.
Logical tag 0x5
--

The asynchronous event looks like this:

--
(gdb) continue
Continuing.

Program received signal SIGSEGV, Segmentation fault
Memory tag violation
Fault address unavailable.
--

gdb/ChangeLog:

2021-03-24  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.
This commit is contained in:
Luis Machado
2020-06-15 15:44:20 -03:00
parent b4a7d4fcfe
commit cf44c9fa1b
3 changed files with 85 additions and 0 deletions
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70
gdb/aarch64-linux-tdep.c
View File

@@ -1685,6 +1685,73 @@ aarch64_linux_memtag_to_string (struct gdbarch *gdbarch, struct value *tag_value
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);
gdb_byte ltag = aarch64_mte_get_ltag (fault_addr);
if (!atag.has_value ())
uiout->text (_("Allocation tag unavailable"));
else
{
uiout->text (_("Allocation tag "));
uiout->field_string ("allocation-tag", hex_string (*atag));
uiout->text ("\n");
uiout->text (_("Logical tag "));
uiout->field_string ("logical-tag", hex_string (ltag));
}
}
else
{
uiout->text ("\n");
uiout->text (_("Fault address unavailable"));
}
}
static void
aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -1765,6 +1832,9 @@ 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. */