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| author | Nicolas Pitre <nicolas.pitre@linaro.org> | 2015-12-12 02:49:21 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-12-17 11:29:01 +0100 |
| commit | 42f25bddd0a226d2431e057b9e01c5cc61067e12 (patch) | |
| tree | 33e3bf9c4669caba06f72303e5d333e2acd15e78 /arch/arm/lib | |
| parent | ARM: 8476/1: VDSO: use PTR_ERR_OR_ZERO for vma check (diff) | |
| download | linux-42f25bddd0a226d2431e057b9e01c5cc61067e12.tar.xz linux-42f25bddd0a226d2431e057b9e01c5cc61067e12.zip | |
ARM: 8477/1: runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()
The ARM compiler inserts calls to __aeabi_idiv() and
__aeabi_uidiv() when it needs to perform division on signed and
unsigned integers. If a processor has support for the sdiv and
udiv instructions, the kernel may overwrite the beginning of those
functions with those instructions and a "bx lr" to get better
performance.
To ensure that those functions are aligned to a 32-bit word for easier
patching (which might not always be the case in Thumb mode) and that
the two patched instructions end up in the same cache line, a 8-byte
alignment is enforced when ARM_PATCH_IDIV is selected.
This was heavily inspired by a previous patch from Stephen Boyd.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/lib')
| -rw-r--r-- | arch/arm/lib/lib1funcs.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S index af2267f6a529..9397b2e532af 100644 --- a/arch/arm/lib/lib1funcs.S +++ b/arch/arm/lib/lib1funcs.S @@ -205,6 +205,10 @@ Boston, MA 02111-1307, USA. */ .endm +#ifdef CONFIG_ARM_PATCH_IDIV + .align 3 +#endif + ENTRY(__udivsi3) ENTRY(__aeabi_uidiv) UNWIND(.fnstart) @@ -253,6 +257,10 @@ UNWIND(.fnstart) UNWIND(.fnend) ENDPROC(__umodsi3) +#ifdef CONFIG_ARM_PATCH_IDIV + .align 3 +#endif + ENTRY(__divsi3) ENTRY(__aeabi_idiv) UNWIND(.fnstart) |