On Thu, Aug 6, 2020 at 3:39 PM Nathan Huckleberry [off-list ref] wrote:

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
[off-list ref] wrote:

quoted

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.

Yeah, I can add that.  It's a little orthogonal though to this patch
that renames labels. I'd consider more so a pre-existing bug.  Let me
add a patch to the series that gives it a new fixup handler, separate
from the label renaming, in a v2 of the series.

quoted

                .long   prev_call, bad_lr
                .popsection

--
2.28.0.163.g6104cc2f0b6-goog

-- 
Thanks,
~Nick Desaulniers

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