[PATCH v2 21/29] ARM: kernel: use PC relative symbol references in suspend/resume code
From: Nicolas Pitre <hidden>
Date: 2017-09-04 18:24:36
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 <redacted>
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.
quoted hunk ↗ jump to hunk
--- 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