diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2015-12-22 08:24:59 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-15 09:19:09 +0200 |
| commit | 94a4e4e467d7a951fcc45e7b49c74eda3e00c7ea (patch) | |
| tree | c30d5e1f7047a78408784626375b2c1e7b09f7aa | |
| parent | 90757afa09b88dbec2a348037edaf65d4e1ac5c4 (diff) | |
ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode
commit 5008efc83bf85b647aa1cbc44718b1675bbb7444 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 2ecc7d15bc09..03120e656aea 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -84,7 +84,6 @@ obj-$(CONFIG_CPU_PJ4B) += pj4-cp0.o obj-$(CONFIG_IWMMXT) += iwmmxt.o obj-$(CONFIG_PERF_EVENTS) += perf_regs.o obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o perf_event_cpu.o -CFLAGS_pj4-cp0.o := -marm AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.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)); } |