From mboxrd@z Thu Jan 1 00:00:00 1970 From: nico@fluxnic.net (Nicolas Pitre) Date: Mon, 12 Aug 2013 12:55:23 -0400 (EDT) Subject: Build error: versatile express In-Reply-To: <20130812124801.GB2823@localhost.localdomain> References: <20130812124801.GB2823@localhost.localdomain> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 12 Aug 2013, Dave Martin wrote: > On Mon, Aug 12, 2013 at 11:28:04AM +0100, Russell King - ARM Linux wrote: > > arch/arm/mach-vexpress/tc2_pm.c: In function 'tc2_pm_down.clone.0': > > arch/arm/mach-vexpress/tc2_pm.c:200:1: error: fp cannot be used in asm here > > > > This is caused by the assembly code in this file clobbering R11, which > > is incompatible with having CONFIG_FRAME_POINTER=y. > > Is there any reason not to fix this just by pushing/popping r11 inside > the asm and removing it from the clobber list? That's most likely the best fix. What about this? ---- >8 From: Nicolas Pitre Date: Mon, 12 Aug 2013 12:47:13 -0400 Subject: [PATCH] ARM: vexpress/MCPM: fix cache disable sequence when CONFIG_FRAME_POINTER=y If CONFIG_FRAME_POINTER=y we hget the following error: arch/arm/mach-vexpress/tc2_pm.c: In function 'tc2_pm_down': arch/arm/mach-vexpress/tc2_pm.c:200:1: error: fp cannot be used in asm here Let's fix that by explicitly preserving r11 on the stack and removing it from the clobber list. Reported-by: Russell King Signed-off-by: Nicolas Pitre diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c index 85fffa702f..3a6384c6c4 100644 --- a/arch/arm/mach-vexpress/dcscb.c +++ b/arch/arm/mach-vexpress/dcscb.c @@ -144,8 +144,13 @@ static void dcscb_power_down(void) * 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" @@ -156,9 +161,10 @@ static void dcscb_power_down(void) "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 " + "dsb \n\t" + "ldr fp, [sp], #4" : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","r11","lr","memory"); + "r9","r10","lr","memory"); /* * This is a harmless no-op. On platforms with a real @@ -182,6 +188,7 @@ static void dcscb_power_down(void) * 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" @@ -192,9 +199,10 @@ static void dcscb_power_down(void) "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 " + "dsb \n\t" + "ldr fp, [sp], #4" : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","r11","lr","memory"); + "r9","r10","lr","memory"); } __mcpm_cpu_down(cpu, cluster); diff --git a/arch/arm/mach-vexpress/tc2_pm.c b/arch/arm/mach-vexpress/tc2_pm.c index dfb55d45b6..9419b1550a 100644 --- a/arch/arm/mach-vexpress/tc2_pm.c +++ b/arch/arm/mach-vexpress/tc2_pm.c @@ -139,8 +139,13 @@ static void tc2_pm_down(u64 residency) * 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" @@ -151,9 +156,10 @@ static void tc2_pm_down(u64 residency) "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 " + "dsb \n\t" + "ldr fp, [sp], #4" : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","r11","lr","memory"); + "r9","r10","lr","memory"); cci_disable_port_by_cpu(mpidr); @@ -174,6 +180,7 @@ static void tc2_pm_down(u64 residency) * 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" @@ -184,9 +191,10 @@ static void tc2_pm_down(u64 residency) "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 " + "dsb \n\t" + "ldr fp, [sp], #4" : : : "r0","r1","r2","r3","r4","r5","r6","r7", - "r9","r10","r11","lr","memory"); + "r9","r10","lr","memory"); } __mcpm_cpu_down(cpu, cluster); > > Since there are no "m" constraints or similar, there should be no > implicit references to fp or sp inside the asm which would be disrupted > by that. > > We could #ifdef it on CONFIG_FRAME_POINTER, but that probably just > uglifies the code for no real benefit. > > > FRAME_POINTER depends on !THUMB2_KERNEL, so we shouldn't hit the same > issue with r7 in Thumb-2. > > Cheers > ---Dave >