| Message ID | 20170903120757.14968-22-ard.biesheuvel@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, 3 Sep 2017, Ard Biesheuvel wrote: > Replace some unnecessary absolute references with relative ones. Also, > to prepare for runtime relocation, which occurs with the caches on, > defer taking the absolute address of cpu_resume_after_mmu() until after > the MMU is enabled. > > Cc: Russell King <linux@armlinux.org.uk> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> What's the point of that last hunk? I understand you load the address after the mMU is on. But you should be coming back from a sleep and caches ought to be clean at that point. Not that it is a bad thing to do but I don't understand your reason for it. > --- > arch/arm/kernel/sleep.S | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S > index f4920b5d0fc4..5b02744f2f12 100644 > --- a/arch/arm/kernel/sleep.S > +++ b/arch/arm/kernel/sleep.S > @@ -60,15 +60,14 @@ > ENTRY(__cpu_suspend) > stmfd sp!, {r4 - r11, lr} > #ifdef MULTI_CPU > - ldr r10, =processor > - ldr r4, [r10, #CPU_SLEEP_SIZE] @ size of CPU sleep state > + ldr_l r4, processor + CPU_SLEEP_SIZE @ size of CPU sleep state > #else > - ldr r4, =cpu_suspend_size > + adr_l r4, cpu_suspend_size > #endif > mov r5, sp @ current virtual SP > add r4, r4, #12 @ Space for pgd, virt sp, phys resume fn > sub sp, sp, r4 @ allocate CPU state on stack > - ldr r3, =sleep_save_sp > + adr_l r3, sleep_save_sp > stmfd sp!, {r0, r1} @ save suspend func arg and pointer > ldr r3, [r3, #SLEEP_SAVE_SP_VIRT] > ALT_SMP(W(nop)) @ don't use adr_l inside ALT_SMP() > @@ -101,13 +100,13 @@ ENDPROC(cpu_suspend_abort) > .align 5 > .pushsection .idmap.text,"ax" > ENTRY(cpu_resume_mmu) > - ldr r3, =cpu_resume_after_mmu > instr_sync > mcr p15, 0, r0, c1, c0, 0 @ turn on MMU, I-cache, etc > mrc p15, 0, r0, c0, c0, 0 @ read id reg > instr_sync > mov r0, r0 > mov r0, r0 > + ldr r3, =cpu_resume_after_mmu > ret r3 @ jump to virtual address > ENDPROC(cpu_resume_mmu) > .popsection > -- > 2.11.0 > >
On 4 September 2017 at 19:24, Nicolas Pitre <nicolas.pitre@linaro.org> wrote: > On Sun, 3 Sep 2017, Ard Biesheuvel wrote: > >> Replace some unnecessary absolute references with relative ones. Also, >> to prepare for runtime relocation, which occurs with the caches on, >> defer taking the absolute address of cpu_resume_after_mmu() until after >> the MMU is enabled. >> >> Cc: Russell King <linux@armlinux.org.uk> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > What's the point of that last hunk? I understand you load the address > after the mMU is on. But you should be coming back from a sleep and > caches ought to be clean at that point. Not that it is a bad thing to do > but I don't understand your reason for it. > I simply attempted to eliminate all uses of relocated quantities with the caches off, but you are correct that this is only necessary for boot and not for suspend/resume. This is actually somewhat of a relief, since there is so much SOC specific suspend/resume code under arch/arm, and the boot code is mostly shared.
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S index f4920b5d0fc4..5b02744f2f12 100644 --- a/arch/arm/kernel/sleep.S +++ b/arch/arm/kernel/sleep.S @@ -60,15 +60,14 @@ ENTRY(__cpu_suspend) stmfd sp!, {r4 - r11, lr} #ifdef MULTI_CPU - ldr r10, =processor - ldr r4, [r10, #CPU_SLEEP_SIZE] @ size of CPU sleep state + ldr_l r4, processor + CPU_SLEEP_SIZE @ size of CPU sleep state #else - ldr r4, =cpu_suspend_size + adr_l r4, cpu_suspend_size #endif mov r5, sp @ current virtual SP add r4, r4, #12 @ Space for pgd, virt sp, phys resume fn sub sp, sp, r4 @ allocate CPU state on stack - ldr r3, =sleep_save_sp + adr_l r3, sleep_save_sp stmfd sp!, {r0, r1} @ save suspend func arg and pointer ldr r3, [r3, #SLEEP_SAVE_SP_VIRT] ALT_SMP(W(nop)) @ don't use adr_l inside ALT_SMP() @@ -101,13 +100,13 @@ ENDPROC(cpu_suspend_abort) .align 5 .pushsection .idmap.text,"ax" ENTRY(cpu_resume_mmu) - ldr r3, =cpu_resume_after_mmu instr_sync mcr p15, 0, r0, c1, c0, 0 @ turn on MMU, I-cache, etc mrc p15, 0, r0, c0, c0, 0 @ read id reg instr_sync mov r0, r0 mov r0, r0 + ldr r3, =cpu_resume_after_mmu ret r3 @ jump to virtual address ENDPROC(cpu_resume_mmu) .popsection
Replace some unnecessary absolute references with relative ones. Also, to prepare for runtime relocation, which occurs with the caches on, defer taking the absolute address of cpu_resume_after_mmu() until after the MMU is enabled. Cc: Russell King <linux@armlinux.org.uk> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm/kernel/sleep.S | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)