[PATCH v2 10/29] ARM: head.S: use PC-relative insn sequences for __fixup_pv_table
From: Nicolas Pitre <hidden>
Date: 2017-09-04 16:47:16
On Sun, 3 Sep 2017, Ard Biesheuvel wrote:
Replace the open coded PC relative offset calculations with adr_l and mov_l invocations. This ensures these quantities are invariant under runtime relocation. Cc: Russell King <linux@armlinux.org.uk> Signed-off-by: Ard Biesheuvel <redacted>
Acked-by: Nicolas Pitre <redacted>
quoted hunk ↗ jump to hunk
--- arch/arm/kernel/head.S | 27 ++++++-------------- 1 file changed, 8 insertions(+), 19 deletions(-)diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index db6b823f20a4..f607e290ef4b 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S@@ -578,14 +578,11 @@ ENDPROC(fixup_smp) */ __HEAD __fixup_pv_table: - adr r0, 1f - ldmia r0, {r3-r7} + adr_l r6, __pv_phys_pfn_offset + adr_l r7, __pv_offset @ __pa(__pv_offset) + mov_l r3, __pv_offset @ __va(__pv_offset) mvn ip, #0 - subs r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET - add r4, r4, r3 @ adjust table start address - add r5, r5, r3 @ adjust table end address - add r6, r6, r3 @ adjust __pv_phys_pfn_offset address - add r7, r7, r3 @ adjust __pv_offset address + subs r3, r7, r3 @ PHYS_OFFSET - PAGE_OFFSET mov r0, r8, lsr #PAGE_SHIFT @ convert to PFN str r0, [r6] @ save computed PHYS_OFFSET to __pv_phys_pfn_offset strcc ip, [r7, #HIGH_OFFSET] @ save to __pv_offset high bits@@ -594,20 +591,15 @@ __fixup_pv_table: THUMB( it ne @ cross section branch ) bne __error str r3, [r7, #LOW_OFFSET] @ save to __pv_offset low bits + adr_l r4, __pv_table_begin + adr_l r5, __pv_table_end b __fixup_a_pv_table ENDPROC(__fixup_pv_table) - - .align -1: .long . - .long __pv_table_begin - .long __pv_table_end -2: .long __pv_phys_pfn_offset - .long __pv_offset + .ltorg .text __fixup_a_pv_table: - adr r0, 3f - ldr r6, [r0] + mov_l r6, __pv_offset add r6, r6, r3 ldr r0, [r6, #HIGH_OFFSET] @ pv_offset high word ldr r6, [r6, #LOW_OFFSET] @ pv_offset low word@@ -676,9 +668,6 @@ ARM_BE8(rev16 ip, ip) #endif ENDPROC(__fixup_a_pv_table) - .align -3: .long __pv_offset - ENTRY(fixup_pv_table) stmfd sp!, {r4 - r7, lr} mov r3, #0 @ no offset-- 2.11.0