[PATCH] riscv: patch: Avoid early page_to_phys()

[Vivian Wang]

Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
page_to_phys()"), avoid using phys_to_page() for the kernel address case
in patch_map().

Since this is called from apply_boot_alternatives() in setup_arch(), and
commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
memory model") has moved sparse_init() to after setup_arch(),
phys_to_page() is not available there yet, and it panics on boot with
SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.

Reported-by: Thomas Weißschuh <thomas.weissschuh at linutronix.de>
Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
Suggested-by: Mike Rapoport <rppt at kernel.org>
Signed-off-by: Vivian Wang <wangruikang at iscas.ac.cn>
---
checkpatch.pl complains about the BUG_ON which was already there
---
 arch/riscv/kernel/patch.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index db13c9ddf9e3..16b243376f36 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -42,19 +42,20 @@ static inline bool is_kernel_exittext(uintptr_t addr)
 static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
 {
 	uintptr_t uintaddr = (uintptr_t) addr;
-	struct page *page;
+	phys_addr_t phys;
 
-	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))
-		page = phys_to_page(__pa_symbol(addr));
-	else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
-		page = vmalloc_to_page(addr);
-	else
+	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) {
+		phys = __pa_symbol(addr);
+	} else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
+		struct page *page = vmalloc_to_page(addr);
+
+		BUG_ON(!page);
+		phys = page_to_phys(page) + offset_in_page(addr);
+	} else {
 		return addr;
+	}
 
-	BUG_ON(!page);
-
-	return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
-					 offset_in_page(addr));
+	return (void *)set_fixmap_offset(fixmap, phys);
 }
 
 static void patch_unmap(int fixmap)

---
base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
change-id: 20260310-riscv-sparsemem-alternatives-fix-f9ea051b1694

Best regards,
-- 
Vivian "dramforever" Wang