Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH 2/9] ARM: change NR_IPIS to 8 | Date | Thu, 18 Feb 2016 15:01:54 +0100 |
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When function tracing for IPIs is enabled, we get a warning for an overflow of the ipi_types array with the IPI_CPU_BACKTRACE type as triggered by raise_nmi():
arch/arm/kernel/smp.c: In function 'raise_nmi': arch/arm/kernel/smp.c:489:2: error: array subscript is above array bounds [-Werror=array-bounds] trace_ipi_raise(target, ipi_types[ipinr]);
This is a correct warning as we actually overflow the array here. To make the tracing work correctly, this extends the array by one entry and increases NR_IPI accordingly.
This only works after patch e7273ff49acf ("ARM: 8488/1: Make IPI_CPU_BACKTRACE a "non-secure" SGI"), which changed the number assignment from '15' to '8'. If we decide to backport this patch to stable kernels, we probably need to backport e7273ff49acf as well.
As far as I can tell, the problem has existed since the tracepoints were originally added, but it only triggered a gcc warning with the later change to NR_IPIS.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: e7273ff49acf ("ARM: 8488/1: Make IPI_CPU_BACKTRACE a "non-secure" SGI") Fixes: 365ec7b17327 ("ARM: add IPI tracepoints") # v3.17 --- arch/arm/include/asm/hardirq.h | 2 +- arch/arm/kernel/smp.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h index 3d7351c844aa..fe3ea776dc34 100644 --- a/arch/arm/include/asm/hardirq.h +++ b/arch/arm/include/asm/hardirq.h @@ -5,7 +5,7 @@ #include <linux/threads.h> #include <asm/irq.h> -#define NR_IPI 7 +#define NR_IPI 8 typedef struct { unsigned int __softirq_pending; diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index b4048e370730..d021566d71c2 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -482,6 +482,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { S(IPI_CPU_STOP, "CPU stop interrupts"), S(IPI_IRQ_WORK, "IRQ work interrupts"), S(IPI_COMPLETION, "completion interrupts"), + S(IPI_CPU_BACKTRACE, "CPU backtrace"), }; static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) -- 2.7.0
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