Commit a2305e3d authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Michael Ellerman
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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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210429080708.1520360-1-arnd@kernel.org
parent d40a82be

arch/powerpc/kexec/crash.c

+2 −2
Original line number Diff line number Diff line
@@ -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");

arch/powerpc/xmon/xmon.c

+11 −11
Original line number Diff line number Diff line
@@ -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)