http://sourceware.org/bugzilla/show_bug.cgi?id=14902
Bug #: 14902
Summary: h8300-elf linker relaxations: symbols skipped
Product: binutils
Version: 2.23
Status: NEW
Severity: normal
Priority: P2
Component: binutils
AssignedTo: [email protected]
ReportedBy: [email protected]
Classification: Unclassified
Created attachment 6767
--> http://sourceware.org/bugzilla/attachment.cgi?id=6767
proposed fix (don't forget to remove the fprintfs)
With binutils 2.23.1, configured with --target=h8300-elf
When relaxations are applied, symbols located after the last instruction of a
.text section do not get updated as they should.
$ cat a.s
.h8300s
.text
.globl _start
.globl _a
.globl _a_end
_start:
_a:
sub r0,r0
jmp @_a
sub r1,r1
jmp @_b
sub r2,r2
_a_end:
$ cat b.s
.h8300s
.text
.globl _b
_b:
sub r0,r0
jmp @_a
sub r1,r1
jmp @_b
sub r2,r2
jmp @_a_end
_b_end:
$ cat Makefile
AS = h8300-elf-as
LD = h8300-elf-ld
result.elf: a.o b.o
$(LD) --relax -mh8300self $^ -o $@
.PHONY: clean
clean:
-rm -f *.o *.elf
.s.o:
$(AS) $< -o $@
Assemble and link the files above (Makefile provided for convenience), then run
h8300-elf-objdump -dr result.elf:
result.elf: file format elf32-h8300
Disassembly of section .text:
00000100 <_a>:
100: 19 00 sub.w r0,r0
102: 40 fc bra .-4 (0x100)
104: 19 11 sub.w r1,r1
106: 40 02 bra .+2 (0x10a)
108: 19 22 sub.w r2,r2
0000010a <_b>:
10a: 19 00 sub.w r0,r0
10c: 40 f2 bra .-14 (0x100)
0000010e <_a_end>:
10e: 19 11 sub.w r1,r1
110: 40 f8 bra .-8 (0x10a)
112: 19 22 sub.w r2,r2
114: 40 f8 bra .-8 (0x10e)
The _a_end symbol has not been adjusted. One problem with this bug is that gcc
often places labels at the end of .text sections; with midly complex programs
and linker scripts, this has led to incorrect code being generated.
I think the problem is in the elf32_h8_relax_delete_bytes() function
(elf32-h8300.c); symbol values are always compared strictly with toaddr. I
think the <= operator should be used instead. The attached patch seems to fix
the issue:
result.elf: file format elf32-h8300
Disassembly of section .text:
00000100 <_a>:
100: 19 00 sub.w r0,r0
102: 40 fc bra .-4 (0x100)
104: 19 11 sub.w r1,r1
106: 40 02 bra .+2 (0x10a)
108: 19 22 sub.w r2,r2
0000010a <_a_end>:
10a: 19 00 sub.w r0,r0
10c: 40 f2 bra .-14 (0x100)
10e: 19 11 sub.w r1,r1
110: 40 f8 bra .-8 (0x10a)
112: 19 22 sub.w r2,r2
114: 40 f4 bra .-12 (0x10a)
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