[3/3] AArch64: Reformat inline-asm in elf_machine_load_address
Commit Message
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
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
@@ -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;
}