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([2804:7f0:8284:1487:34cb:6ef2:6b7f:4db2]) by smtp.gmail.com with ESMTPSA id j202sm12284027qke.108.2020.11.16.08.46.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Nov 2020 08:46:02 -0800 (PST) Subject: Re: [PATCH v3 16/24] AArch64: Report tag violation error information To: David Spickett References: <20201109170435.15766-1-luis.machado@linaro.org> <20201109170435.15766-17-luis.machado@linaro.org> Message-ID: Date: Mon, 16 Nov 2020 13:45:59 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Luis Machado via Gdb-patches Reply-To: Luis Machado Cc: gdb-patches@sourceware.org Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" On 11/16/20 12:43 PM, David Spickett wrote: >> +aarch64_linux_report_signal_info (struct gdbarch *gdbarch, >> + struct ui_out *uiout, >> + enum gdb_signal siggnal) > > siggnal -> signal > This is a GDB-ism. The hook itself is named like that. I don't like the name, but I thought I'd leave it the same just to keep it standard. > Also a nit about the formatting. > > Copying from 20/24 of v3: >> +Memory tag violation while accessing address 0x0000fffff7ff8000 >> +Allocation tag 0x0000000000000001. > > (I'm guessing the code to print the "Allocation tag" line lives here > in some part) > > Would it make more sense to either not align the tag value to > anything, or to align it to the size of the architecture's tag? Which > would be 4 bits in this case so the same either way. We could print it without leading zeroes. That may make things a bit more compact. Would that work? > > On Mon, 9 Nov 2020 at 17:05, Luis Machado wrote: >> >> 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. >> >> gdb/ChangeLog: >> >> YYYY-MM-DD Luis Machado >> >> * 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 | 64 ++++++++++++++++++++++++++++++++++++ >> gdb/arch/aarch64-mte-linux.h | 6 ++++ >> 2 files changed, 70 insertions(+) >> >> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c >> index 39b1790263..70e180e1cb 100644 >> --- a/gdb/aarch64-linux-tdep.c >> +++ b/gdb/aarch64-linux-tdep.c >> @@ -1626,6 +1626,67 @@ 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 ("$_siginfo.si_code\n"); >> + >> + fault_addr >> + = parse_and_eval_long ("$_siginfo._sifields._sigfault.si_addr"); >> + } >> + catch (const gdb_exception &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"); >> + >> + CORE_ADDR atag; >> + if (aarch64_linux_get_atag (fault_addr, &atag) != 0) >> + uiout->text (_("Allocation tag unavailable")); >> + else >> + { >> + uiout->text (_("Allocation tag ")); >> + uiout->field_core_addr ("allocation-tag", gdbarch, atag); >> + } >> + } >> + else >> + { >> + uiout->text ("\n"); >> + uiout->text (_("Fault address unavailable")); >> + } >> +} >> + >> static void >> aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) >> { >> @@ -1706,6 +1767,9 @@ 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 5c5783f28b..a5a980ed49 100644 >> --- a/gdb/arch/aarch64-mte-linux.h >> +++ b/gdb/arch/aarch64-mte-linux.h >> @@ -35,6 +35,12 @@ >> #define MTE_LOGICAL_TAG_START_BIT 56 >> #define MTE_LOGICAL_MAX_VALUE 0xf >> >> +/* Memory tagging definitions. */ >> +#ifndef SEGV_MTEAERR >> +# define SEGV_MTEAERR 8 >> +# define SEGV_MTESERR 9 >> +#endif >> + >> /* Return the number of tag granules in the memory range >> [ADDR, ADDR + LEN) given GRANULE_SIZE. */ >> extern size_t get_tag_granules (CORE_ADDR addr, size_t len, >> -- >> 2.17.1 >>