I'm creating a polymorphic-code and I have an issue with the LDRD instruction that is making me crazy, I cannot see it. NMI hardfault at execution obviously. I'm on a STM32L4A6AG. Problem probably resides in assembly code but could maybe also be on opcode generation (Ignored by disassembler?).
Data is taken before ldrd execution:
My code:
2004ffc0: 0xbff36f8f isb sy
2004ffc4: 0xbff34f8f dsb sy
2004ffc8: 0x000020b5 push {r5, lr}
2004ffca: 0xdff80c50 ldr.w r5, [pc, #12] ; 0x2004ffd8
2004ffce: 0xdfe90301 ldrd r0, r1, [pc, #12] ; 0x2004ffdc
2004ffd2: 0x0000a847 blx r5
2004ffd4: 0x000000bf nop
2004ffd6: 0x000020bd pop {r5, pc}
Registers:
r0 0x0 (Hex)
r1 0x1 (Hex)
r2 0x2004ffc0 (Hex)
r3 0x2004ffbf (Hex)
r4 0xaabbccdd (Hex)
r5 0x80107e1 (Hex)
r6 0x0 (Hex)
r7 0x2004ff98 (Hex)
r8 0
r9 0
r10 0
r11 0
r12 0
sp 0x2004ff90
lr 0x80104ed (Hex)
pc 0x2004ffce
Memory:
x/9wx 0x2004ffc0
0x2004ffc0: 0x8f6ff3bf 0x8f4ff3bf 0xf8dfb520 0xe9df500c
0x2004ffd0: 0x47a80103 0xbd20bf00 0x080107e1 0xeeffaabb
0x2004ffe0: 0xaabbccdd
x/18hx 0x2004ffc0
0x2004ffc0: 0xf3bf 0x8f6f 0xf3bf 0x8f4f 0xb520 0xf8df 0x500c 0xe9df
0x2004ffd0: 0x0103 0x47a8 0xbf00 0xbd20 0x07e1 0x0801 0xaabb 0xeeff
0x2004ffe0: 0xccdd 0xaabb
Thanks guys!
According to the ARM manual, ldrd
instructions with a pc
-relative addressing mode must be be word-aligned on ARMv7-M parts. If the assembler does not take care of this quirk, manual alignment may be needed:
.align
ldrd r0, r1, [pc, #12]
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