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authorAndrey Smirnov <andrew.smirnov@gmail.com>2018-08-07 14:00:37 -0700
committerSascha Hauer <s.hauer@pengutronix.de>2018-08-08 09:34:07 +0200
commitf9fc8254b23c765750f07ccb26327dec0d3307e8 (patch)
tree55d91c4164654afd35e35844114271cd718e049b
parentcc13a6109ad79946e119917e7bbed16acc9b1e97 (diff)
downloadbarebox-f9fc8254b23c765750f07ccb26327dec0d3307e8.tar.gz
ARM: Mark SP as being clobbered in arm_setup_stack()
Not sure why it was working before, but with recent update of AArch64 GCC to 8.1.1 on my Fedora 28 machine, compiling barebox_arm_entry() yields the following assembly: 0000000000002aac <barebox_arm_entry>: 2aac: a9bd7bfd stp x29, x30, [sp, #-48]! 2ab0: d1404023 sub x3, x1, #0x10, lsl #12 2ab4: d1004063 sub x3, x3, #0x10 2ab8: 910003fd mov x29, sp 2abc: 8b000063 add x3, x3, x0 2ac0: a90153f3 stp x19, x20, [sp, #16] 2ac4: aa0003f3 mov x19, x0 2ac8: aa0103f4 mov x20, x1 2acc: f90017e2 str x2, [sp, #40] <-- storing 'boarddata' on old stack 2ad0: 9100007f mov sp, x3 <-- setting up new stack 2ad4: 97ffffdd bl 2a48 <arm_early_mmu_cache_invalidate> 2ad8: f94017e2 ldr x2, [sp, #40] <--- sadness 2adc: aa1403e1 mov x1, x20 2ae0: aa1303e0 mov x0, x19 2ae4: 940000a1 bl 2d68 <barebox_multi_pbl_start> Which result in AArch64 image (i.MX8MQ) not being bootable. With SP marked as clobbered, the above assembly changes to the following: 0000000000002aac <barebox_arm_entry>: 2aac: a9bd7bfd stp x29, x30, [sp, #-48]! 2ab0: d1404023 sub x3, x1, #0x10, lsl #12 2ab4: d1004063 sub x3, x3, #0x10 2ab8: 910003fd mov x29, sp 2abc: a90153f3 stp x19, x20, [sp, #16] 2ac0: 8b000063 add x3, x3, x0 2ac4: aa0003f3 mov x19, x0 2ac8: aa0103f4 mov x20, x1 2acc: f90017a2 str x2, [x29, #40] 2ad0: 9100007f mov sp, x3 2ad4: 97ffffdd bl 2a48 <arm_early_mmu_cache_invalidate> 2ad8: f94017a2 ldr x2, [x29, #40] 2adc: aa1403e1 mov x1, x20 2ae0: aa1303e0 mov x0, x19 2ae4: 940000a1 bl 2d68 <barebox_multi_pbl_start> now x29 is used to access stored x2 which avoids the problem and allows the system to boot correctly. The change is a no-op on AArch32. Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r--arch/arm/include/asm/common.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/arm/include/asm/common.h b/arch/arm/include/asm/common.h
index 97bfdc4..c32cdfe 100644
--- a/arch/arm/include/asm/common.h
+++ b/arch/arm/include/asm/common.h
@@ -48,7 +48,10 @@ static inline unsigned long get_sp(void)
static inline void arm_setup_stack(unsigned long top)
{
- __asm__ __volatile__("mov sp, %0" : : "r"(top));
+ __asm__ __volatile__("mov sp, %0"
+ :
+ : "r"(top)
+ : "sp");
}
#endif /* __ASM_ARM_COMMON_H */