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Sat, 05 Sep 2026 12:30:02 -0700 (PDT) From: Matt Turner Date: Sat, 05 Sep 2026 15:29:38 -0400 Subject: [PATCH v2 17/22] alpha: select SYSCTL_EXCEPTION_TRACE Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260905-arch-kconfig-options-v2-v2-17-83e8245761a2@gmail.com> References: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> In-Reply-To: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> To: Richard Henderson , Magnus Lindholm , Kees Cook , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, Matt Turner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2633; i=mattst88@gmail.com; h=from:subject:message-id; bh=qrjdKgOfiKlVqpd955ImNGsDNT2gjKCr1YxX8TKeUE4=; b=owGbwMvMwCW25rVmCc8sv+mMp9WSGLLm5E7Zf1Vx/u3FyhNePmjMKOnUWDmlKmv2/PMiyhf+a m1/ZK4X0/GRhUGMi2GmmCJL3HpFllltO5b6nJb+BTOHlQlkiLRIAwMQsDDw5SbmlRrpGOmZahvq GQIZOkbxEDk9Bo3M4uLS1CLdtIIih7z8ksSSzPy8Yr38gtS8gvQCvbTMtJKMjPyi4lSgEXp5qSW mro5uRoYGJpaOFmZOFo6mJs7OToZObo6Ozq5ORpbmJgbOlo4mrpbmDFycAjDXVOxmZGjWyJ1l33 C68M/Jq/X3H3IeuWJ0VjA7/JpZ9e+V1YHN0csY/nBOfKk2x6Hz655luyZIqDDWbvkfMdvtqbDaw ROFPQYf/JkB X-Developer-Key: i=mattst88@gmail.com; a=openpgp; fpr=3BB639E56F861FA2E86505690FDD682D974CA72A Report unhandled user faults the way other architectures do, and hook up the debug.exception-trace sysctl that controls the reporting. The message gives the faulting address, the PC and the user stack pointer, and is rate limited. Assisted-by: Claude:claude-opus-5 Signed-off-by: Matt Turner Tested-by: Magnus Lindholm Reviewed-by: Magnus Lindholm --- arch/alpha/Kconfig | 1 + arch/alpha/mm/fault.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index f2a5b8c8688a..b9ff67370877 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -61,6 +61,7 @@ config ALPHA select MMU_GATHER_NO_RANGE select MMU_GATHER_RCU_TABLE_FREE select SPARSEMEM_EXTREME if SPARSEMEM + select SYSCTL_EXCEPTION_TRACE select ZONE_DMA select TRACE_IRQFLAGS_SUPPORT select ARCH_WANT_FRAME_POINTERS diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c index a9816bbc9f34..dfe427d93072 100644 --- a/arch/alpha/mm/fault.c +++ b/arch/alpha/mm/fault.c @@ -27,8 +27,32 @@ #include #include +#include + extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *); +int show_unhandled_signals = 1; + +static void +show_signal_msg(struct pt_regs *regs, unsigned long address, int signo, + const char *desc) +{ + const char *level; + + if (!show_unhandled_signals || !unhandled_signal(current, signo)) + return; + if (!printk_ratelimit()) + return; + + /* Losing init is fatal, so shout about it. */ + level = task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG; + + printk("%s%s[%d]: %s at %016lx pc %016lx sp %016lx\n", + level, current->comm, task_pid_nr(current), desc, + address, regs->pc, rdusp()); + print_vma_addr(KERN_CONT " in ", regs->pc); + printk(KERN_CONT "\n"); +} /* * Force a new ASN for a task. @@ -217,12 +241,17 @@ do_page_fault(unsigned long address, unsigned long mmcsr, mmap_read_unlock(mm); /* Send a sigbus, regardless of whether we were in kernel or user mode. */ + if (user_mode(regs)) + show_signal_msg(regs, address, SIGBUS, "bus error"); force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address); if (!user_mode(regs)) goto no_context; return; do_sigsegv: + show_signal_msg(regs, address, SIGSEGV, + si_code == SEGV_MAPERR ? "unmapped access" + : "access violation"); force_sig_fault(SIGSEGV, si_code, (void __user *) address); return; -- 2.54.0