[3/3] AArch64: Reformat inline-asm in elf_machine_load_address

Message ID 1416329010-8683-4-git-send-email-will.newton@linaro.org
State New
Headers show

Commit Message

Will Newton Nov. 18, 2014, 4:43 p.m.
From: Andrew Pinski <apinski@cavium.com>

This patch reformats the inline-asm in elf_machine_load_address so it is
easier to change only part of the inline-asm.  That is using string
concatenating instead of string continuation.

Also document why this inline-asm works - it depends on the 32bit
relocation being resolved at link time.

ChangeLog:

2014-11-18  Will Newton  <will.newton@linaro.org>
	    Andrew Pinski  <andrew.pinski@caviumnetworks.com>

	* sysdeps/aarch64/dl-machine.h (elf_machine_load_address):
	Refactor inline-asm.  Also add comment.
---
 sysdeps/aarch64/dl-machine.h | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

Comments

Marcus Shawcroft Nov. 21, 2014, 2:39 p.m. | #1
On 18 November 2014 16:43, Will Newton <will.newton@linaro.org> wrote:
> From: Andrew Pinski <apinski@cavium.com>
>
> This patch reformats the inline-asm in elf_machine_load_address so it is
> easier to change only part of the inline-asm.  That is using string
> concatenating instead of string continuation.
>
> Also document why this inline-asm works - it depends on the 32bit
> relocation being resolved at link time.
>
> ChangeLog:
>
> 2014-11-18  Will Newton  <will.newton@linaro.org>
>             Andrew Pinski  <andrew.pinski@caviumnetworks.com>
>
>         * sysdeps/aarch64/dl-machine.h (elf_machine_load_address):
>         Refactor inline-asm.  Also add comment.

OK /Marcus

Patch

diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
index 7f5ce2b..1294369 100644
--- a/sysdeps/aarch64/dl-machine.h
+++ b/sysdeps/aarch64/dl-machine.h
@@ -52,19 +52,22 @@  elf_machine_load_address (void)
      The choice of symbol is arbitrary. The static address we obtain
      by constructing a non GOT reference to the symbol, the dynamic
      address of the symbol we compute using adrp/add to compute the
-     symbol's address relative to the PC. */
+     symbol's address relative to the PC.
+     This depends on 32bit relocations being resolved at link time
+     and that the static address fits in the 32bits.  */
 
   ElfW(Addr) static_addr;
   ElfW(Addr) dynamic_addr;
 
-  asm ("					\n\
-	adrp	%1, _dl_start;			\n\
-        add	%1, %1, #:lo12:_dl_start        \n\
-        ldr	%w0, 1f				\n\
-	b	2f				\n\
-1:	.word	_dl_start			\n\
-2:						\n\
-       " : "=r" (static_addr),  "=r" (dynamic_addr));
+  asm ("					\n"
+"	adrp	%1, _dl_start;			\n"
+"	add	%1, %1, #:lo12:_dl_start	\n"
+"	ldr	%w0, 1f				\n"
+"	b	2f				\n"
+"1:						\n"
+"	.word	_dl_start			\n"
+"2:						\n"
+    : "=r" (static_addr),  "=r" (dynamic_addr));
   return dynamic_addr - static_addr;
 }