Hi Jean,
On Mon, Mar 03, 2014 at 09:53:21AM +0000, Jean Pihet wrote:
Introducing perf_regs_load function, which is going to be used for dwarf unwind test in following patches.
It takes single argument as a pointer to the regs dump buffer and populates it with current registers values.
[...]
diff --git a/tools/perf/arch/arm/tests/regs_load.S b/tools/perf/arch/arm/tests/regs_load.S new file mode 100644 index 0000000..241c6df --- /dev/null +++ b/tools/perf/arch/arm/tests/regs_load.S @@ -0,0 +1,51 @@ +#include <linux/linkage.h>
+#define R0 0x00 +#define R1 0x08
Why are you using a 64-bit stride for 32-bit registers? (which prevents you from using stm later on).
+.text +.type perf_regs_load,%function +ENTRY(perf_regs_load)
- push {r1}
Do you only push r1 here so that you can do the stack arithmetic later? That doesn't make sense to me -- can't you str sp directly?
- str r0, [r0, #R0]
- str r1, [r0, #R1]
- str r2, [r0, #R2]
- str r3, [r0, #R3]
- str r4, [r0, #R4]
- str r5, [r0, #R5]
- str r6, [r0, #R6]
- str r7, [r0, #R7]
- str r8, [r0, #R8]
- str r9, [r0, #R9]
- str sl, [r0, #SL]
- str fp, [r0, #FP]
- str ip, [r0, #IP]
- add r1, sp, #4 @ Retrieve and save sp at entry time
- str r1, [r0, #SP]
- str lr, [r0, #LR]
- str lr, [r0, #PC] @ Save caller PC
This isn't necessarily the `caller PC' (depending on how you define it). It's the return address, which is probably (but not always) the instruction following the branch to this function.
Will