linux-kernel - [PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

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Date: Wed,  8 May 2024 21:19:17 +0200
From: Nam Cao <namcao@...utronix.de>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

With XIP kernel, kernel_map.size is set to be only the size of data part of
the kernel. This is inconsistent with "normal" kernel, who sets it to be
the size of the entire kernel.

More importantly, XIP kernel fails to boot if CONFIG_DEBUG_VIRTUAL is
enabled, because there are checks on virtual addresses with the assumption
that kernel_map.size is the size of the entire kernel (these checks are in
arch/riscv/mm/physaddr.c).

Change XIP's kernel_map.size to be the size of the entire kernel.

Signed-off-by: Nam Cao <namcao@...utronix.de>
Cc: <stable@...r.kernel.org> # v6.1+
---
I wouldn't consider this inconsistency to be a bug. It only became a
a problem after kernel_map.size is used to check virtual addresses in
5f763b3b5960 ("riscv: Fix DEBUG_VIRTUAL false warnings"). So I will only
backport this to stable versions that contain this commit: v6.1+

 arch/riscv/mm/init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c081e7d349b1..0c0562839899 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -903,7 +903,7 @@ static void __init create_kernel_page_table(pgd_t *pgdir,
 				   PMD_SIZE, PAGE_KERNEL_EXEC);
 
 	/* Map the data in RAM */
-	end_va = kernel_map.virt_addr + XIP_OFFSET + kernel_map.size;
+	end_va = kernel_map.virt_addr + kernel_map.size;
 	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
 		create_pgd_mapping(pgdir, va,
 				   kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
@@ -1072,7 +1072,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 
 	phys_ram_base = CONFIG_PHYS_RAM_BASE;
 	kernel_map.phys_addr = (uintptr_t)CONFIG_PHYS_RAM_BASE;
-	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);
+	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_start);
 
 	kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom;
 #else
-- 
2.39.2