| Message ID | 20150409082116.GV12732@n2100.arm.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thursday 09 April 2015 09:21:16 Russell King - ARM Linux wrote: > On Thu, Apr 09, 2015 at 10:13:06AM +0200, Arnd Bergmann wrote: > > > > With this in linux-next, I get a build failure on randconfig kernels with > > THUMB2_KERNEL enabled: > > > > arch/arm/mm/cache-v7.S: Assembler messages: > > arch/arm/mm/cache-v7.S:99: Error: ALT_UP() content must assemble to exactly 4 bytes > > > > Any idea for a method that will work with all combinations of SMP/UP > > and ARM/THUMB? The best I could come up with was to add an extra 'mov r0,r0', > > but that gets rather ugly as you then have to do it only for THUMB2. > > How about we make ALT_UP() add the additional padding? Something like > this maybe? > > diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h > index f67fd3afebdf..79f421796aab 100644 > --- a/arch/arm/include/asm/assembler.h > +++ b/arch/arm/include/asm/assembler.h > @@ -237,6 +237,9 @@ > .pushsection ".alt.smp.init", "a" ;\ > .long 9998b ;\ > 9997: instr ;\ > + .if . - 9997b == 2 ;\ > + nop ;\ > + .endif > .if . - 9997b != 4 ;\ > .error "ALT_UP() content must assemble to exactly 4 bytes";\ > .endif ;\ > This looks like a good solution, and works fine after adding the missing ';\' characters behind the .endif. I don't expect any problems but I'm doing some more randconfig builds now with this patch, and if you don't hear back today, feel free to add Acked-by: Arnd Bergmann <arnd@arndb.de> Thanks! Arnd
On Thu, Apr 09, 2015 at 09:21:16AM +0100, Russell King - ARM Linux wrote: > On Thu, Apr 09, 2015 at 10:13:06AM +0200, Arnd Bergmann wrote: > > On Friday 03 April 2015 11:54:32 Russell King wrote: > > > diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S > > > index 5b5d0c00bca7..793d061b4dce 100644 > > > --- a/arch/arm/mm/cache-v7.S > > > +++ b/arch/arm/mm/cache-v7.S > > > @@ -93,17 +93,18 @@ ENTRY(v7_flush_dcache_louis) > > > ALT_SMP(mov r3, r0, lsr #20) @ move LoUIS into position > > > ALT_UP( mov r3, r0, lsr #26) @ move LoUU into position > > > ands r3, r3, #7 << 1 @ extract LoU*2 field from clidr > > > + bne start_flush_levels @ LoU != 0, start flushing > > > #ifdef CONFIG_ARM_ERRATA_643719 > > > - ALT_SMP(mrceq p15, 0, r2, c0, c0, 0) @ read main ID register > > > - ALT_UP(reteq lr) @ LoUU is zero, so nothing to do > > > - movweq r1, #:lower16:0x410fc090 @ ID of ARM Cortex A9 r0p? > > > - movteq r1, #:upper16:0x410fc090 > > > - biceq r2, r2, #0x0000000f @ clear minor revision number > > > - teqeq r2, r1 @ test for errata affected core and if so... > > > - moveqs r3, #1 << 1 @ fix LoUIS value (and set flags state to 'ne') > > > +ALT_SMP(mrc p15, 0, r2, c0, c0, 0) @ read main ID register > > > +ALT_UP( ret lr) @ LoUU is zero, so nothing to do > > > + movw r1, #:lower16:0x410fc090 @ ID of ARM Cortex A9 r0p? > > > > With this in linux-next, I get a build failure on randconfig kernels with > > THUMB2_KERNEL enabled: > > > > arch/arm/mm/cache-v7.S: Assembler messages: > > arch/arm/mm/cache-v7.S:99: Error: ALT_UP() content must assemble to exactly 4 bytes > > > > Any idea for a method that will work with all combinations of SMP/UP > > and ARM/THUMB? The best I could come up with was to add an extra 'mov r0,r0', > > but that gets rather ugly as you then have to do it only for THUMB2. > > How about we make ALT_UP() add the additional padding? Something like > this maybe? > > diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h > index f67fd3afebdf..79f421796aab 100644 > --- a/arch/arm/include/asm/assembler.h > +++ b/arch/arm/include/asm/assembler.h > @@ -237,6 +237,9 @@ > .pushsection ".alt.smp.init", "a" ;\ > .long 9998b ;\ > 9997: instr ;\ > + .if . - 9997b == 2 ;\ > + nop ;\ > + .endif > .if . - 9997b != 4 ;\ > .error "ALT_UP() content must assemble to exactly 4 bytes";\ > .endif ;\ I wonder whether, as a general rule, it's better to use the 4-byte wide instruction where possible instead of the additional nop. Anyway, this could be left with the ALT_* macros user.
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index f67fd3afebdf..79f421796aab 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -237,6 +237,9 @@ .pushsection ".alt.smp.init", "a" ;\ .long 9998b ;\ 9997: instr ;\ + .if . - 9997b == 2 ;\ + nop ;\ + .endif .if . - 9997b != 4 ;\ .error "ALT_UP() content must assemble to exactly 4 bytes";\ .endif ;\