linux-kernel - [PATCH 1/2] riscv: Fix XIP_FIXUP_FLASH

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Date:   Thu, 20 Jan 2022 15:33:37 +0000
From:   Myrtle Shah <gatecat@....me>
To:     linux-riscv@...ts.infradead.org, paul.walmsley@...ive.com,
        palmer@...belt.com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] riscv: Fix XIP_FIXUP_FLASH_OFFSET

There were several problems with the calculation. Not only was an 'and'
being computed into t1 but thrown away; but the 'and' itself would
cause problems if the granularity of the XIP physical address was less
than XIP_OFFSET - in my case I had the kernel image at 2MB in SPI flash.

I believe this approach is more generic.

Fixes: f9ace4ede49b ("riscv: remove .text section size limitation for XIP")

Signed-off-by: Myrtle Shah <gatecat@....me>
---
 arch/riscv/kernel/head.S | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 604d60292dd8..b1ca65abeb1e 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -21,14 +21,13 @@
 	add \reg, \reg, t0
 .endm
 .macro XIP_FIXUP_FLASH_OFFSET reg
-	la t1, __data_loc
-	li t0, XIP_OFFSET_MASK
-	and t1, t1, t0
-	li t1, XIP_OFFSET
-	sub t0, t0, t1
-	sub \reg, \reg, t0
+	la t0, __data_loc
+	REG_L t1, _xip_phys_offset
+	sub \reg, \reg, t1
+	add \reg, \reg, t0
 .endm
 _xip_fixup: .dword CONFIG_PHYS_RAM_BASE - CONFIG_XIP_PHYS_ADDR - XIP_OFFSET
+_xip_phys_offset: .dword CONFIG_XIP_PHYS_ADDR + XIP_OFFSET
 #else
 .macro XIP_FIXUP_OFFSET reg
 .endm
-- 
2.34.1