* [PATCH][AArch64][gas] Set the minimum alignment on code segments.
@ 2015-03-05 11:30 Matthew Wahab
2015-03-10 10:22 ` Nicholas Clifton
0 siblings, 1 reply; 2+ messages in thread
From: Matthew Wahab @ 2015-03-05 11:30 UTC (permalink / raw)
To: binutils
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On AArch64, gas doesn't set the minimum alignment for code segments
making it possible for a segment to become misaligned during a link. It
is also inconsistent with the ABI (4.3.5: Section Alignment).
This patch sets the minimum alignment for a section to 4 bytes, if the
section contains an instruction.
A similar issue in the ARM backend has already been fixed
(https://sourceware.org/bugzilla/show_bug.cgi?id=12931).
Tested aarch64-none-linux-gnu and aarch64-none-elf with check-gas,
check-ld, check-binutils.
Ok for trunk?
Matthew
gas/
2015-03-05 Matthew Wahab <matthew.wahab@arm.com>
* config/tc-aarch64.c (mapping_state): Set minimum alignment for
code sections.
gas/testsuite
2015-03-05 Matthew Wahab <matthew.wahab@arm.com>
* gas/aarch64/codealign.d: Add test for code section alignment.
* gas/aarch64/codealign.s: New file.
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[-- Attachment #2: codealign.patch --]
[-- Type: text/x-patch; name=codealign.patch, Size: 1756 bytes --]
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index 9179fc6..77701c6 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -1478,7 +1478,14 @@ mapping_state (enum mstate state)
/* The mapping symbol has already been emitted.
There is nothing else to do. */
return;
- else if (TRANSITION (MAP_UNDEFINED, MAP_DATA))
+
+ if (state == MAP_INSN)
+ /* AArch64 instructions require 4-byte alignment. When emitting
+ instructions into any section, record the appropriate section
+ alignment. */
+ record_alignment (now_seg, 2);
+
+ if (TRANSITION (MAP_UNDEFINED, MAP_DATA))
/* This case will be evaluated later in the next else. */
return;
else if (TRANSITION (MAP_UNDEFINED, MAP_INSN))
diff --git a/gas/testsuite/gas/aarch64/codealign.d b/gas/testsuite/gas/aarch64/codealign.d
new file mode 100644
index 0000000..8e75c87
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/codealign.d
@@ -0,0 +1,16 @@
+#objdump: --section-headers
+# Minimum code alignment should be set.
+# This test is only valid on ELF based ports.
+#not-target: *-*-*coff *-*-pe *-*-wince *-*-*aout* *-*-netbsd *-*-riscix*
+
+.*: +file format.*aarch64.*
+
+Sections:
+Idx Name Size VMA LMA File off Algn
+ 0 \.text .* .* .* .* 2\*\*2
+ .*CODE.*
+ 1 \.data .* .* .* .* 2\*\*0
+ .*DATA.*
+ 2 \.bss .* .* .* .* 2\*\*0
+.*
+
diff --git a/gas/testsuite/gas/aarch64/codealign.s b/gas/testsuite/gas/aarch64/codealign.s
new file mode 100644
index 0000000..b80a6d9
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/codealign.s
@@ -0,0 +1,2 @@
+.text
+ nop
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH][AArch64][gas] Set the minimum alignment on code segments.
2015-03-05 11:30 [PATCH][AArch64][gas] Set the minimum alignment on code segments Matthew Wahab
@ 2015-03-10 10:22 ` Nicholas Clifton
0 siblings, 0 replies; 2+ messages in thread
From: Nicholas Clifton @ 2015-03-10 10:22 UTC (permalink / raw)
To: Matthew Wahab, binutils
Hi Matthew,
> gas/
> 2015-03-05 Matthew Wahab <matthew.wahab@arm.com>
>
> * config/tc-aarch64.c (mapping_state): Set minimum alignment for
> code sections.
>
>
> gas/testsuite
> 2015-03-05 Matthew Wahab <matthew.wahab@arm.com>
>
> * gas/aarch64/codealign.d: Add test for code section alignment.
> * gas/aarch64/codealign.s: New file.
Approved - please apply.
Cheers
Nick
^ permalink raw reply [flat|nested] 2+ messages in thread
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