From: Nicolas Pitre nicolas.pitre@linaro.org
Commit 39792c7cf3111d69dc4aa0923859d8b929e9039f upstream
This code is becoming duplicated in many places. So let's consolidate it into a handy macro that is known to be right and available for reuse.
Signed-off-by: Nicolas Pitre nico@linaro.org Acked-by: Dave Martin Dave.Martin@arm.com Signed-off-by: Russell King rmk+kernel@arm.linux.org.uk Signed-off-by: Jon Medhurst tixy@linaro.org --- arch/arm/include/asm/cacheflush.h | 46 ++++++++++++++++++++++++++++++ arch/arm/mach-vexpress/dcscb.c | 56 +++---------------------------------- arch/arm/mach-vexpress/tc2_pm.c | 48 ++----------------------------- 3 files changed, 52 insertions(+), 98 deletions(-)
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index 17d0ae8..beb8702 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -436,4 +436,50 @@ static inline void __sync_cache_range_r(volatile void *p, size_t size) #define sync_cache_w(ptr) __sync_cache_range_w(ptr, sizeof *(ptr)) #define sync_cache_r(ptr) __sync_cache_range_r(ptr, sizeof *(ptr))
+/* + * Disabling cache access for one CPU in an ARMv7 SMP system is tricky. + * To do so we must: + * + * - Clear the SCTLR.C bit to prevent further cache allocations + * - Flush the desired level of cache + * - Clear the ACTLR "SMP" bit to disable local coherency + * + * ... and so without any intervening memory access in between those steps, + * not even to the stack. + * + * WARNING -- After this has been called: + * + * - No ldrex/strex (and similar) instructions must be used. + * - The CPU is obviously no longer coherent with the other CPUs. + * - This is unlikely to work as expected if Linux is running non-secure. + * + * Note: + * + * - This is known to apply to several ARMv7 processor implementations, + * however some exceptions may exist. Caveat emptor. + * + * - The clobber list is dictated by the call to v7_flush_dcache_*. + * fp is preserved to the stack explicitly prior disabling the cache + * since adding it to the clobber list is incompatible with having + * CONFIG_FRAME_POINTER=y. ip is saved as well if ever r12-clobbering + * trampoline are inserted by the linker and to keep sp 64-bit aligned. + */ +#define v7_exit_coherency_flush(level) \ + asm volatile( \ + "stmfd sp!, {fp, ip} \n\t" \ + "mrc p15, 0, r0, c1, c0, 0 @ get SCTLR \n\t" \ + "bic r0, r0, #"__stringify(CR_C)" \n\t" \ + "mcr p15, 0, r0, c1, c0, 0 @ set SCTLR \n\t" \ + "isb \n\t" \ + "bl v7_flush_dcache_"__stringify(level)" \n\t" \ + "clrex \n\t" \ + "mrc p15, 0, r0, c1, c0, 1 @ get ACTLR \n\t" \ + "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" \ + "mcr p15, 0, r0, c1, c0, 1 @ set ACTLR \n\t" \ + "isb \n\t" \ + "dsb \n\t" \ + "ldmfd sp!, {fp, ip}" \ + : : : "r0","r1","r2","r3","r4","r5","r6","r7", \ + "r9","r10","lr","memory" ) + #endif diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c index 19a7d08..b35700f 100644 --- a/arch/arm/mach-vexpress/dcscb.c +++ b/arch/arm/mach-vexpress/dcscb.c @@ -134,38 +134,8 @@ static void dcscb_power_down(void) if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) { arch_spin_unlock(&dcscb_lock);
- /* - * Flush all cache levels for this cluster. - * - * To do so we do: - * - Clear the SCTLR.C bit to prevent further cache allocations - * - Flush the whole cache - * - Clear the ACTLR "SMP" bit to disable local coherency - * - * Let's do it in the safest possible way i.e. with - * no memory access within the following sequence - * including to the stack. - * - * Note: fp is preserved to the stack explicitly prior doing - * this since adding it to the clobber list is incompatible - * with having CONFIG_FRAME_POINTER=y. - */ - asm volatile( - "str fp, [sp, #-4]! \n\t" - "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" - "bic r0, r0, #"__stringify(CR_C)" \n\t" - "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" - "isb \n\t" - "bl v7_flush_dcache_all \n\t" - "clrex \n\t" - "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" - "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" - "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" - "isb \n\t" - "dsb \n\t" - "ldr fp, [sp], #4" - : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","lr","memory"); + /* Flush all cache levels for this cluster. */ + v7_exit_coherency_flush(all);
/* * This is a harmless no-op. On platforms with a real @@ -184,26 +154,8 @@ static void dcscb_power_down(void) } else { arch_spin_unlock(&dcscb_lock);
- /* - * Flush the local CPU cache. - * Let's do it in the safest possible way as above. - */ - asm volatile( - "str fp, [sp, #-4]! \n\t" - "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" - "bic r0, r0, #"__stringify(CR_C)" \n\t" - "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" - "isb \n\t" - "bl v7_flush_dcache_louis \n\t" - "clrex \n\t" - "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" - "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" - "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" - "isb \n\t" - "dsb \n\t" - "ldr fp, [sp], #4" - : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","lr","memory"); + /* Disable and flush the local CPU cache. */ + v7_exit_coherency_flush(louis); }
__mcpm_cpu_down(cpu, cluster); diff --git a/arch/arm/mach-vexpress/tc2_pm.c b/arch/arm/mach-vexpress/tc2_pm.c index 9221903..9fc264a 100644 --- a/arch/arm/mach-vexpress/tc2_pm.c +++ b/arch/arm/mach-vexpress/tc2_pm.c @@ -147,32 +147,7 @@ static void tc2_pm_down(u64 residency) : : "r" (0x400) ); }
- /* - * We need to disable and flush the whole (L1 and L2) cache. - * Let's do it in the safest possible way i.e. with - * no memory access within the following sequence - * including the stack. - * - * Note: fp is preserved to the stack explicitly prior doing - * this since adding it to the clobber list is incompatible - * with having CONFIG_FRAME_POINTER=y. - */ - asm volatile( - "str fp, [sp, #-4]! \n\t" - "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" - "bic r0, r0, #"__stringify(CR_C)" \n\t" - "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" - "isb \n\t" - "bl v7_flush_dcache_all \n\t" - "clrex \n\t" - "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" - "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" - "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" - "isb \n\t" - "dsb \n\t" - "ldr fp, [sp], #4" - : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","lr","memory"); + v7_exit_coherency_flush(all);
cci_disable_port_by_cpu(mpidr);
@@ -188,26 +163,7 @@ static void tc2_pm_down(u64 residency)
arch_spin_unlock(&tc2_pm_lock);
- /* - * We need to disable and flush only the L1 cache. - * Let's do it in the safest possible way as above. - */ - asm volatile( - "str fp, [sp, #-4]! \n\t" - "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t" - "bic r0, r0, #"__stringify(CR_C)" \n\t" - "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t" - "isb \n\t" - "bl v7_flush_dcache_louis \n\t" - "clrex \n\t" - "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t" - "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" - "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t" - "isb \n\t" - "dsb \n\t" - "ldr fp, [sp], #4" - : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","lr","memory"); + v7_exit_coherency_flush(louis); }
__mcpm_cpu_down(cpu, cluster);