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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2015-12-22 08:24:59 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2016-01-04 11:12:10 +0000 |
| commit | 5008efc83bf85b647aa1cbc44718b1675bbb7444 (patch) | |
| tree | 728eb22528c2db224e9aec379df4fabec18dfd6a /arch/arm/kernel | |
| parent | 36f46d6d5cdef2308027261d633e96807d64d098 (diff) | |
| download | linux-5008efc83bf85b647aa1cbc44718b1675bbb7444.tar.gz | |
ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode
The PJ4 inline asm sequence to write to cp15 cannot be built in Thumb-2 mode, due to the way it performs arithmetic on the program counter, so it is built in ARM mode instead. However, building C files in ARM mode under CONFIG_THUMB2_KERNEL is problematic, since the instrumentation performed by subsystems like ftrace does not expect having to deal with interworking branches. Since the sequence in question is simply a poor man's ISB instruction, let's use a straight 'isb' instead when building in Thumb2 mode. Thumb2 implies V7, so 'isb' should always be supported in that case. Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm/kernel/pj4-cp0.c | 4 |
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index af9e59bf3831..3c789496297f 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -73,7 +73,6 @@ obj-$(CONFIG_IWMMXT) += iwmmxt.o obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o obj-$(CONFIG_HW_PERF_EVENTS) += perf_event_xscale.o perf_event_v6.o \ perf_event_v7.o -CFLAGS_pj4-cp0.o := -marm AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.o obj-$(CONFIG_VDSO) += vdso.o diff --git a/arch/arm/kernel/pj4-cp0.c b/arch/arm/kernel/pj4-cp0.c index 8153e36b2491..7c9248b74d3f 100644 --- a/arch/arm/kernel/pj4-cp0.c +++ b/arch/arm/kernel/pj4-cp0.c @@ -66,9 +66,13 @@ static void __init pj4_cp_access_write(u32 value) __asm__ __volatile__ ( "mcr p15, 0, %1, c1, c0, 2\n\t" +#ifdef CONFIG_THUMB2_KERNEL + "isb\n\t" +#else "mrc p15, 0, %0, c1, c0, 2\n\t" "mov %0, %0\n\t" "sub pc, pc, #4\n\t" +#endif : "=r" (temp) : "r" (value)); } |