| Message ID | 1447397933-13379-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 13 November 2015 at 19:48, Stephen Boyd <sboyd@codeaurora.org> wrote: > On 11/13, Ard Biesheuvel wrote: >> The PJ4 inline asm sequences in pj4-cp0.c 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. >> >> So instead, revert to building pj4-cp0.c in Thumb-2 mode, and move the >> offending sequence to iwmmxt.S, which is not instrumented anyway, and is >> already built in ARM mode unconditionally. >> >> Reported-by: Stephen Boyd <sboyd@codeaurora.org> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> --- > > Tested-by: Stephen Boyd <sboyd@codeaurora.org> > Thanks. I've put this into the patch system (8452/1) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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/iwmmxt.S b/arch/arm/kernel/iwmmxt.S index 49fadbda8c63..e1776bf52480 100644 --- a/arch/arm/kernel/iwmmxt.S +++ b/arch/arm/kernel/iwmmxt.S @@ -14,6 +14,7 @@ * published by the Free Software Foundation. */ +#include <linux/init.h> #include <linux/linkage.h> #include <asm/ptrace.h> #include <asm/thread_info.h> @@ -370,3 +371,23 @@ ENDPROC(iwmmxt_task_release) concan_owner: .word 0 +#if defined(CONFIG_CPU_PJ4) || defined(CONFIG_CPU_PJ4B) + + __INIT + +ENTRY(pj4_cp_access_read) + mrc p15, 0, r0, c1, c0, 2 + ret lr +ENDPROC(pj4_cp_access_read) + +ENTRY(pj4_cp_access_write) + mcr p15, 0, r0, c1, c0, 2 + mrc p15, 0, r0, c1, c0, 2 + mov r0, r0 + sub pc, pc, #4 + ret lr +ENDPROC(pj4_cp_access_write) + + __FINIT + +#endif diff --git a/arch/arm/kernel/pj4-cp0.c b/arch/arm/kernel/pj4-cp0.c index 8153e36b2491..4f226e175734 100644 --- a/arch/arm/kernel/pj4-cp0.c +++ b/arch/arm/kernel/pj4-cp0.c @@ -49,28 +49,8 @@ static struct notifier_block __maybe_unused iwmmxt_notifier_block = { .notifier_call = iwmmxt_do, }; - -static u32 __init pj4_cp_access_read(void) -{ - u32 value; - - __asm__ __volatile__ ( - "mrc p15, 0, %0, c1, c0, 2\n\t" - : "=r" (value)); - return value; -} - -static void __init pj4_cp_access_write(u32 value) -{ - u32 temp; - - __asm__ __volatile__ ( - "mcr p15, 0, %1, c1, c0, 2\n\t" - "mrc p15, 0, %0, c1, c0, 2\n\t" - "mov %0, %0\n\t" - "sub pc, pc, #4\n\t" - : "=r" (temp) : "r" (value)); -} +asmlinkage u32 pj4_cp_access_read(void); +asmlinkage void pj4_cp_access_write(u32 value); static int __init pj4_get_iwmmxt_version(void) {
The PJ4 inline asm sequences in pj4-cp0.c 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. So instead, revert to building pj4-cp0.c in Thumb-2 mode, and move the offending sequence to iwmmxt.S, which is not instrumented anyway, and is already built in ARM mode unconditionally. Reported-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm/kernel/Makefile | 1 - arch/arm/kernel/iwmmxt.S | 21 +++++++++++++++++++++ arch/arm/kernel/pj4-cp0.c | 24 ++---------------------- 3 files changed, 23 insertions(+), 23 deletions(-) -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel