On Mon, Nov 18, 2013 at 10:49:50PM -0800, Victor Kamensky wrote:
After "ARM: signal: sigreturn_codes should be endian neutral to work in BE8" commit, thumb only platforms, like armv7m, fails to compile sigreturn_codes.S. The reason is that for such arch values '.arm' directive and arm opcodes are not allowed.
Fix conditionally enables arm opcodes only if no CONFIG_CPU_THUMBONLY defined and it uses .org instructions to keep sigreturn_codes layout.
Suggested-by: Dave Martin Dave.Martin@arm.com Signed-off-by: Victor Kamensky victor.kamensky@linaro.org
arch/arm/kernel/sigreturn_codes.S | 40 ++++++++++++++++++++++++++++++--------- 1 file changed, 31 insertions(+), 9 deletions(-)
diff --git a/arch/arm/kernel/sigreturn_codes.S b/arch/arm/kernel/sigreturn_codes.S index 3c5d0f2..9d48fe9 100644 --- a/arch/arm/kernel/sigreturn_codes.S +++ b/arch/arm/kernel/sigreturn_codes.S @@ -30,6 +30,27 @@
- snippets.
*/ +/*
- In CPU_THUMBONLY case kernel arm opcodes are not allowed.
- Note in this case codes skips those instructions but it uses .org
- directive to keep correct layout of sigreturn_codes array.
- */
+#ifndef CONFIG_CPU_THUMBONLY +#define ARM_INSTR(code...) code
Minor nit, but you have a space before the tab before code, where the 'X' is, below:
#define ARM_INSTR(code...)X code
Another minor one:
Since this is a local macro, it would make the code a bit tidier if you reduced the length of the name to 7 chars or less so that we can fit the macro name into the left margin without messing up the indenting.
Perhaps HAS_ARM or ARM_OK are good names:
insn1 arg1, arg2 ARM_OK(insn2 args )
Some people seem to tab out all the right )s to the same column at beyond the right-hand edge of all the neighbouring instructions, but that's purely cosmetic. It helps to separate out the visual noise of the macros from the instructions themselves when reading.
+#else +#define ARM_INSTR(code...) +#endif
+.macro arm_slot n
.org sigreturn_codes + 12 * (\n)+ARM_INSTR( .arm ) +.endm
+.macro thumb_slot n
.org sigreturn_codes + 12 * (\n) + 8.thumb+.endm
#if __LINUX_ARM_ARCH__ <= 4 /* * Note we manually set minimally required arch that supports @@ -45,26 +66,27 @@ .global sigreturn_codes .type sigreturn_codes, #object
- .arm
- .align
sigreturn_codes: /* ARM sigreturn syscall code snippet */
- mov r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)
- swi #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)
+arm_slot 0 +ARM_INSTR(mov r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)) +ARM_INSTR(swi #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)) /* Thumb sigreturn syscall code snippet */
- .thumb
+thumb_slot 0 movs r7, #(__NR_sigreturn - __NR_SYSCALL_BASE) swi #0 /* ARM sigreturn_rt syscall code snippet */
- .arm
- mov r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)
- swi #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)
+arm_slot 1 +ARM_INSTR(mov r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)) +ARM_INSTR(swi #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)) /* Thumb sigreturn_rt syscall code snippet */
- .thumb
+thumb_slot 1 movs r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE) swi #0 @@ -74,7 +96,7 @@ sigreturn_codes: * it is thumb case or not, so we need additional * word after real last entry. */
- .arm
+arm_slot 2 .space 4 .size sigreturn_codes, . - sigreturn_codes
Otherwise, this looks OK to me.
It seems to work at least back to binutils 2.18, so the chance of this spoiling anyone's day seems minimal.
Cheers ---Dave