| Message ID | alpine.LFD.2.20.1511172255410.22569@knanqh.ubzr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Nicolas, On Wed, Nov 18, 2015 at 12:58 PM, Nicolas Pitre <nico@fluxnic.net> wrote: > On Tue, 17 Nov 2015, Chris Brandt wrote: > >> I think this one is more of a coding issue. >> These were the attempts to fix the temporary stack issue: >> >> My first patch: >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/357106.html >> >> Magnus's try: >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/383394.html > > Here's my proposal: > > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > index de2b246fed..2d0ac32320 100644 > --- a/arch/arm/mm/proc-v7.S > +++ b/arch/arm/mm/proc-v7.S > @@ -274,10 +274,12 @@ __v7_ca15mp_setup: > __v7_b15mp_setup: > __v7_ca17mp_setup: > mov r10, #0 > -1: adr r12, __v7_setup_stack @ the local stack > - stmia r12, {r0-r5, lr} @ v7_invalidate_l1 touches r0-r6 > +1: adr r0, __v7_setup_stack_ptr > + ldr r12, [r0] > + add r12, r12, r0 @ the local stack > + stmia r12, {r1-r6, lr} @ v7_invalidate_l1 touches r0-r6 > bl v7_invalidate_l1 > - ldmia r12, {r0-r5, lr} > + ldmia r12, {r1-r6, lr} > #ifdef CONFIG_SMP > ALT_SMP(mrc p15, 0, r0, c1, c0, 1) > ALT_UP(mov r0, #(1 << 6)) @ fake it for UP [snip] > @@ -480,11 +484,16 @@ __errata_finish: > orr r0, r0, r6 @ set them > THUMB( orr r0, r0, #1 << 30 ) @ Thumb exceptions > ret lr @ return to head.S:__ret > + > + .align 2 > +__v7_setup_stack_ptr: > + .word __v7_setup_stack - . > ENDPROC(__v7_setup) Thanks for your take on this. I did a couple of local implementations before submitting, and one of the issues I ran into was the need to get rid of PAGE_OFFSET due to the code running without MMU enabled. I suppose that is taken care of the "__v7_setup_stack - ." calculation above? Cheers, / magnus
On Wed, 18 Nov 2015, Magnus Damm wrote: > Hi Nicolas, > > On Wed, Nov 18, 2015 at 12:58 PM, Nicolas Pitre <nico@fluxnic.net> wrote: > > On Tue, 17 Nov 2015, Chris Brandt wrote: > > > >> I think this one is more of a coding issue. > >> These were the attempts to fix the temporary stack issue: > >> > >> My first patch: > >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/357106.html > >> > >> Magnus's try: > >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/383394.html > > > > Here's my proposal: > > > > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > > index de2b246fed..2d0ac32320 100644 > > --- a/arch/arm/mm/proc-v7.S > > +++ b/arch/arm/mm/proc-v7.S > > @@ -274,10 +274,12 @@ __v7_ca15mp_setup: > > __v7_b15mp_setup: > > __v7_ca17mp_setup: > > mov r10, #0 > > -1: adr r12, __v7_setup_stack @ the local stack > > - stmia r12, {r0-r5, lr} @ v7_invalidate_l1 touches r0-r6 > > +1: adr r0, __v7_setup_stack_ptr > > + ldr r12, [r0] > > + add r12, r12, r0 @ the local stack > > + stmia r12, {r1-r6, lr} @ v7_invalidate_l1 touches r0-r6 > > bl v7_invalidate_l1 > > - ldmia r12, {r0-r5, lr} > > + ldmia r12, {r1-r6, lr} > > #ifdef CONFIG_SMP > > ALT_SMP(mrc p15, 0, r0, c1, c0, 1) > > ALT_UP(mov r0, #(1 << 6)) @ fake it for UP > > [snip] > > > @@ -480,11 +484,16 @@ __errata_finish: > > orr r0, r0, r6 @ set them > > THUMB( orr r0, r0, #1 << 30 ) @ Thumb exceptions > > ret lr @ return to head.S:__ret > > + > > + .align 2 > > +__v7_setup_stack_ptr: > > + .word __v7_setup_stack - . > > ENDPROC(__v7_setup) > > Thanks for your take on this. I did a couple of local implementations > before submitting, and one of the issues I ran into was the need to > get rid of PAGE_OFFSET due to the code running without MMU enabled. I > suppose that is taken care of the "__v7_setup_stack - ." calculation > above? Yes. That provides the offset from __v7_setup_stack_ptr to reach __v7_setup_stack. And __v7_setup_stack_ptr is obtained with adr which is relative to the current pc. So this works whether or not the MMU is enabled. Nicolas
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index de2b246fed..2d0ac32320 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -274,10 +274,12 @@ __v7_ca15mp_setup: __v7_b15mp_setup: __v7_ca17mp_setup: mov r10, #0 -1: adr r12, __v7_setup_stack @ the local stack - stmia r12, {r0-r5, lr} @ v7_invalidate_l1 touches r0-r6 +1: adr r0, __v7_setup_stack_ptr + ldr r12, [r0] + add r12, r12, r0 @ the local stack + stmia r12, {r1-r6, lr} @ v7_invalidate_l1 touches r0-r6 bl v7_invalidate_l1 - ldmia r12, {r0-r5, lr} + ldmia r12, {r1-r6, lr} #ifdef CONFIG_SMP ALT_SMP(mrc p15, 0, r0, c1, c0, 1) ALT_UP(mov r0, #(1 << 6)) @ fake it for UP @@ -415,10 +417,12 @@ __v7_pj4b_setup: #endif /* CONFIG_CPU_PJ4B */ __v7_setup: - adr r12, __v7_setup_stack @ the local stack - stmia r12, {r0-r5, lr} @ v7_invalidate_l1 touches r0-r6 + adr r0, __v7_setup_stack_ptr + ldr r12, [r0] + add r12, r12, r0 @ the local stack + stmia r12, {r1-r6, lr} @ v7_invalidate_l1 touches r0-r6 bl v7_invalidate_l1 - ldmia r12, {r0-r5, lr} + ldmia r12, {r1-r6, lr} __v7_setup_cont: and r0, r9, #0xff000000 @ ARM? @@ -480,11 +484,16 @@ __errata_finish: orr r0, r0, r6 @ set them THUMB( orr r0, r0, #1 << 30 ) @ Thumb exceptions ret lr @ return to head.S:__ret + + .align 2 +__v7_setup_stack_ptr: + .word __v7_setup_stack - . ENDPROC(__v7_setup) + .bss .align 2 __v7_setup_stack: - .space 4 * 7 @ 12 registers + .space 4 * 7 @ 7 registers __INITDATA diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S index 67d9209077..8cd465927a 100644 --- a/arch/arm/mm/proc-v7m.S +++ b/arch/arm/mm/proc-v7m.S @@ -123,10 +123,12 @@ __v7m_setup: ret lr ENDPROC(__v7m_setup) + .pushsection .bss .align 2 __v7m_setup_stack: .space 4 * 8 @ 8 registers __v7m_setup_stack_top: + .previous define_processor_functions v7m, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1