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Thu, 29 Apr 2021 18:07:36 +1000 (AEST) Received: by mail.kernel.org (Postfix) with ESMTPSA id 08B9E61446; Thu, 29 Apr 2021 08:07:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619683652; bh=2DlbYxunUevwnqh+Ong8MaEHb0LiPaIl1Ok8WmzGuC0=; h=From:To:Cc:Subject:Date:From; b=mymJPklfL0ZdniTD3N+MWED8nyjPviqzLYjhTAO9CwOtOlMAc5Yikt0vbNuMpsMcq JJcLc8HGlhvjlKM94tLwKjShqHZQ+6JgLliD1lz+WxxHaDN1V0m1FTVk0IeMQDJn/O f2t0RwiL5h+1KtZy5SB8QFo3zjbTv/SgBa28WbpwaC+drlFM6tXiC5vXASU3qu996F VrLQk6nuZMtZMvU95X3Pp3ZqofFnubP+rS1eKkUeqkD8/6iuaCAt+wuohcmb0uk+UA plLQVK9tGKsIcd4rtNkQxruxahYKNzyKeGNZI7MmIl7hoWRvduXtaYGv91cmaBf/IW rmtY1ZJj8MZAQ== From: Arnd Bergmann To: Michael Ellerman Subject: [PATCH] powerpc: mark local variables around longjmp as volatile Date: Thu, 29 Apr 2021 10:06:38 +0200 Message-Id: <20210429080708.1520360-1-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ravi Bangoria , Arnd Bergmann , linux-kernel@vger.kernel.org, Paul Mackerras , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Arnd Bergmann gcc-11 points out that modifying local variables next to a longjmp/setjmp may cause undefined behavior: arch/powerpc/kexec/crash.c: In function 'crash_kexec_prepare_cpus.constprop': arch/powerpc/kexec/crash.c:108:22: error: variable 'ncpus' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbere d] arch/powerpc/kexec/crash.c:109:13: error: variable 'tries' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbere d] arch/powerpc/xmon/xmon.c: In function 'xmon_print_symbol': arch/powerpc/xmon/xmon.c:3625:21: error: variable 'name' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'stop_spus': arch/powerpc/xmon/xmon.c:4057:13: error: variable 'i' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'restart_spus': arch/powerpc/xmon/xmon.c:4098:13: error: variable 'i' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'dump_opal_msglog': arch/powerpc/xmon/xmon.c:3008:16: error: variable 'pos' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'show_pte': arch/powerpc/xmon/xmon.c:3207:29: error: variable 'tsk' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'show_tasks': arch/powerpc/xmon/xmon.c:3302:29: error: variable 'tsk' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c: In function 'xmon_core': arch/powerpc/xmon/xmon.c:494:13: error: variable 'cmd' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c:860:21: error: variable 'bp' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c:860:21: error: variable 'bp' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] arch/powerpc/xmon/xmon.c:492:48: error: argument 'fromipi' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered] According to the documentation, marking these as 'volatile' is sufficient to avoid the problem, and it shuts up the warning. Signed-off-by: Arnd Bergmann --- arch/powerpc/kexec/crash.c | 4 ++-- arch/powerpc/xmon/xmon.c | 22 +++++++++++----------- 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c index 0196d0c211ac..10f997e6bb95 100644 --- a/arch/powerpc/kexec/crash.c +++ b/arch/powerpc/kexec/crash.c @@ -105,8 +105,8 @@ void crash_ipi_callback(struct pt_regs *regs) static void crash_kexec_prepare_cpus(int cpu) { unsigned int msecs; - unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ - int tries = 0; + volatile unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ + volatile int tries = 0; int (*old_handler)(struct pt_regs *regs); printk(KERN_EMERG "Sending IPI to other CPUs\n"); diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index c8173e92f19d..ce0eacf77645 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -489,10 +489,10 @@ static void xmon_touch_watchdogs(void) touch_nmi_watchdog(); } -static int xmon_core(struct pt_regs *regs, int fromipi) +static int xmon_core(struct pt_regs *regs, volatile int fromipi) { - int cmd = 0; - struct bpt *bp; + volatile int cmd = 0; + struct bpt *volatile bp; long recurse_jmp[JMP_BUF_LEN]; bool locked_down; unsigned long offset; @@ -857,7 +857,7 @@ static inline void force_enable_xmon(void) static struct bpt *at_breakpoint(unsigned long pc) { int i; - struct bpt *bp; + struct bpt *volatile bp; bp = bpts; for (i = 0; i < NBPTS; ++i, ++bp) @@ -3005,7 +3005,7 @@ static void dump_opal_msglog(void) { unsigned char buf[128]; ssize_t res; - loff_t pos = 0; + volatile loff_t pos = 0; if (!firmware_has_feature(FW_FEATURE_OPAL)) { printf("Machine is not running OPAL firmware.\n"); @@ -3160,7 +3160,7 @@ memzcan(void) printf("%.8lx\n", a - mskip); } -static void show_task(struct task_struct *tsk) +static void show_task(struct task_struct *volatile tsk) { char state; @@ -3204,7 +3204,7 @@ static void format_pte(void *ptep, unsigned long pte) static void show_pte(unsigned long addr) { unsigned long tskv = 0; - struct task_struct *tsk = NULL; + struct task_struct *volatile tsk = NULL; struct mm_struct *mm; pgd_t *pgdp; p4d_t *p4dp; @@ -3299,7 +3299,7 @@ static void show_pte(unsigned long addr) static void show_tasks(void) { unsigned long tskv; - struct task_struct *tsk = NULL; + struct task_struct *volatile tsk = NULL; printf(" task_struct ->thread.ksp ->thread.regs PID PPID S P CMD\n"); @@ -3622,7 +3622,7 @@ static void xmon_print_symbol(unsigned long address, const char *mid, const char *after) { char *modname; - const char *name = NULL; + const char *volatile name = NULL; unsigned long offset, size; printf(REG, address); @@ -4054,7 +4054,7 @@ void xmon_register_spus(struct list_head *list) static void stop_spus(void) { struct spu *spu; - int i; + volatile int i; u64 tmp; for (i = 0; i < XMON_NUM_SPUS; i++) { @@ -4095,7 +4095,7 @@ static void stop_spus(void) static void restart_spus(void) { struct spu *spu; - int i; + volatile int i; for (i = 0; i < XMON_NUM_SPUS; i++) { if (!spu_info[i].spu) -- 2.29.2