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SubjectRe: [PATCH 3/4] ARM: backtrace-clang: give labels more descriptive names
The style cleanup looks great. I just have one extra thing that
can probably be thrown into this patch.

On Thu, Jul 30, 2020 at 3:51 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> Removes the 1004 label; it was neither a control flow target, nor an
> instruction we expect to produce a fault.
>
> Gives the labels slightly more readable names. The `b` suffixes are
> handy to disambiguate between labels of the same identifier when there's
> more than one. Since these labels are unique, let's just give them
> names.
>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> arch/arm/lib/backtrace-clang.S | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm/lib/backtrace-clang.S b/arch/arm/lib/backtrace-clang.S
> index 40eb2215eaf4..7dad2a6843a5 100644
> --- a/arch/arm/lib/backtrace-clang.S
> +++ b/arch/arm/lib/backtrace-clang.S
> @@ -121,8 +121,8 @@ for_each_frame: tst frame, mask @ Check for address exceptions
> * start. This value gets updated to be the function start later if it is
> * possible.
> */
> -1001: ldr sv_pc, [frame, #4] @ get saved 'pc'
> -1002: ldr sv_fp, [frame, #0] @ get saved fp
> +load_pc: ldr sv_pc, [frame, #4] @ get saved 'pc'
> +load_fp: ldr sv_fp, [frame, #0] @ get saved fp
>
> teq sv_fp, mask @ make sure next frame exists
> beq no_frame
> @@ -142,7 +142,7 @@ for_each_frame: tst frame, mask @ Check for address exceptions
> * registers for the current function, but the stacktrace is still printed
> * properly.
> */
> -1003: ldr sv_lr, [sv_fp, #4] @ get saved lr from next frame
> +load_lr: ldr sv_lr, [sv_fp, #4] @ get saved lr from next frame
>
> tst sv_lr, #0 @ If there's no previous lr,
> beq finished_setup @ we're done.
> @@ -166,8 +166,7 @@ finished_setup:
> /*
> * Print the function (sv_pc) and where it was called from (sv_lr).
> */
> -1004: mov r0, sv_pc
> -
> + mov r0, sv_pc
> mov r1, sv_lr
> mov r2, frame
> bic r1, r1, mask @ mask PC/LR for the mode
> @@ -182,7 +181,7 @@ finished_setup:
> * pointer the comparison will fail and no registers will print. Unwinding will
> * continue as if there had been no registers stored in this frame.
> */
> -1005: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, lr}
> +load_stmfd: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, lr}
> ldr r3, .Lopcode @ instruction exists,
> teq r3, r1, lsr #11
> ldr r0, [frame] @ locals are stored in
> @@ -201,7 +200,7 @@ finished_setup:
> mov frame, sv_fp @ above the current frame
> bhi for_each_frame
>
> -1006: adr r0, .Lbad
> +bad_frame: adr r0, .Lbad
> mov r1, loglvl
> mov r2, frame
> bl printk
> @@ -216,11 +215,10 @@ bad_lr: mov sv_fp, #0
> ENDPROC(c_backtrace)
> .pushsection __ex_table,"a"
> .align 3
> - .long 1001b, 1006b
> - .long 1002b, 1006b
> - .long 1003b, 1006b
> - .long 1004b, 1006b
> - .long 1005b, 1006b
> + .long load_pc, bad_frame
> + .long load_fp, bad_frame
> + .long load_lr, bad_frame
> + .long load_stmfd, bad_frame

Load_stmfd should get its own fixup
handler since it should emit errors about a bad
pc, not a bad frame pointer.

> .long prev_call, bad_lr
> .popsection
>
> --
> 2.28.0.163.g6104cc2f0b6-goog
>

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