linux-kernel - [PATCH 1/3] arm64: clean up trampoline vector loads

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Date:   Mon, 16 Mar 2020 14:40:44 +0200
From:   Rémi Denis-Courmont <remi@...lab.net>
To:     catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     mark.rutland@....com, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] arm64: clean up trampoline vector loads

From: Rémi Denis-Courmont <remi.denis.courmont@...wei.com>

This switches from custom instruction patterns to the regular large
memory model sequence with ADRP and LDR. In doing so, the ADD
instruction can be eliminated in the SDEI handler, and the code no
longer assumes that the trampoline vectors and the vectors address both
start on a page boundary.

Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@...wei.com>
---
 arch/arm64/kernel/entry.S | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index e5d4e30ee242..24f828739696 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -805,9 +805,9 @@ alternative_else_nop_endif
 2:
 	tramp_map_kernel	x30
 #ifdef CONFIG_RANDOMIZE_BASE
-	adr	x30, tramp_vectors + PAGE_SIZE
+	adrp	x30, tramp_vectors + PAGE_SIZE
 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
-	ldr	x30, [x30]
+	ldr	x30, [x30, #:lo12:__entry_tramp_data_start]
 #else
 	ldr	x30, =vectors
 #endif
@@ -953,9 +953,8 @@ SYM_CODE_START(__sdei_asm_entry_trampoline)
 1:	str	x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)]
 
 #ifdef CONFIG_RANDOMIZE_BASE
-	adr	x4, tramp_vectors + PAGE_SIZE
-	add	x4, x4, #:lo12:__sdei_asm_trampoline_next_handler
-	ldr	x4, [x4]
+	adrp	x4, tramp_vectors + PAGE_SIZE
+	ldr	x4, [x4, #:lo12:__sdei_asm_trampoline_next_handler]
 #else
 	ldr	x4, =__sdei_asm_handler
 #endif
-- 
2.25.1