| Message ID | 1384843790-14394-2-git-send-email-victor.kamensky@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello, 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> Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Best regards and thanks Uwe
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
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 +#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
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(-)