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@xxxxxxxxx>
---
arch/arm/include/asm/common.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/common.h b/arch/arm/include/asm/common.h
index 97bfdc43f..c32cdfe5e 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 */
--
2.17.1
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