From a2305e3de819394a7adf68078964a92d06f9db33 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 29 Apr 2021 10:06:38 +0200 Subject: [PATCH] powerpc: mark local variables around longjmp as volatile 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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210429080708.1520360-1-arnd@kernel.org --- 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 0196d0c..10f997e 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 12dcfb5..fe34c4f 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -499,10 +499,10 @@ 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; @@ -872,7 +872,7 @@ 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) @@ -3109,7 +3109,7 @@ 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"); @@ -3264,7 +3264,7 @@ 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; @@ -3308,7 +3308,7 @@ 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; @@ -3403,7 +3403,7 @@ 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"); @@ -3726,7 +3726,7 @@ 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); @@ -4158,7 +4158,7 @@ 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++) { @@ -4199,7 +4199,7 @@ 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) -- 2.7.4