[PATCH v2 1/2] riscv: Fix crash during early errata patching

[PATCH v2 1/2] riscv: Fix crash during early errata patching

[Samuel Holland]

The patch function for the T-Head PBMT errata calls __pa_symbol() before
relocation. This crashes when CONFIG_DEBUG_VIRTUAL is enabled, because
__pa_symbol() forwards to __phys_addr_symbol(), and __phys_addr_symbol()
checks against the absolute kernel start/end address.

Fix this by checking against the kernel map instead of a symbol address.

Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Samuel Holland <samuel@sholland.org>
---

Changes in v2:
 - Fix __phys_addr_symbol instead of avoiding it in the errata code

 arch/riscv/mm/physaddr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
index 19cf25a74ee2..9b18bda74154 100644
--- a/arch/riscv/mm/physaddr.c
+++ b/arch/riscv/mm/physaddr.c
@@ -22,7 +22,7 @@ EXPORT_SYMBOL(__virt_to_phys);
 phys_addr_t __phys_addr_symbol(unsigned long x)
 {
 	unsigned long kernel_start = kernel_map.virt_addr;
-	unsigned long kernel_end = (unsigned long)_end;
+	unsigned long kernel_end = kernel_start + kernel_map.size;
 
 	/*
 	 * Boundary checking aginst the kernel image mapping.
-- 
2.37.4


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[PATCH v2 2/2] riscv: Move cast inside kernel_mapping_[pv]a_to_[vp]a

[Samuel Holland]

Before commit 44c922572952 ("RISC-V: enable XIP"), these macros cast
their argument to unsigned long. That commit moved the cast after an
assignment to an unsigned long variable, rendering it ineffectual.
Move the cast back, so we can remove the cast at each call site.

Reviewed-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Samuel Holland <samuel@sholland.org>
---

(no changes since v1)

 arch/riscv/include/asm/page.h | 18 +++++++++---------
 arch/riscv/mm/init.c          | 16 ++++++++--------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index ac70b0fd9a9a..9f432c1b5289 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -123,20 +123,20 @@ extern phys_addr_t phys_ram_base;
 	((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < PAGE_OFFSET + KERN_VIRT_SIZE))
 
 #define linear_mapping_pa_to_va(x)	((void *)((unsigned long)(x) + kernel_map.va_pa_offset))
-#define kernel_mapping_pa_to_va(y)	({						\
-	unsigned long _y = y;								\
-	(IS_ENABLED(CONFIG_XIP_KERNEL) && _y < phys_ram_base) ?					\
-		(void *)((unsigned long)(_y) + kernel_map.va_kernel_xip_pa_offset) :		\
-		(void *)((unsigned long)(_y) + kernel_map.va_kernel_pa_offset + XIP_OFFSET);	\
+#define kernel_mapping_pa_to_va(y)	({					\
+	unsigned long _y = (unsigned long)(y);					\
+	(IS_ENABLED(CONFIG_XIP_KERNEL) && _y < phys_ram_base) ?			\
+		(void *)(_y + kernel_map.va_kernel_xip_pa_offset) :		\
+		(void *)(_y + kernel_map.va_kernel_pa_offset + XIP_OFFSET);	\
 	})
 #define __pa_to_va_nodebug(x)		linear_mapping_pa_to_va(x)
 
 #define linear_mapping_va_to_pa(x)	((unsigned long)(x) - kernel_map.va_pa_offset)
 #define kernel_mapping_va_to_pa(y) ({						\
-	unsigned long _y = y;							\
-	(IS_ENABLED(CONFIG_XIP_KERNEL) && _y < kernel_map.virt_addr + XIP_OFFSET) ?	\
-		((unsigned long)(_y) - kernel_map.va_kernel_xip_pa_offset) :		\
-		((unsigned long)(_y) - kernel_map.va_kernel_pa_offset - XIP_OFFSET);	\
+	unsigned long _y = (unsigned long)(y);					\
+	(IS_ENABLED(CONFIG_XIP_KERNEL) && _y < kernel_map.virt_addr + XIP_OFFSET) ? \
+		(_y - kernel_map.va_kernel_xip_pa_offset) :			\
+		(_y - kernel_map.va_kernel_pa_offset - XIP_OFFSET);		\
 	})
 
 #define __va_to_pa_nodebug(x)	({						\
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 50a1b6edd491..dc1ddfa6dedc 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -926,15 +926,15 @@ static void __init pt_ops_set_early(void)
  */
 static void __init pt_ops_set_fixmap(void)
 {
-	pt_ops.alloc_pte = kernel_mapping_pa_to_va((uintptr_t)alloc_pte_fixmap);
-	pt_ops.get_pte_virt = kernel_mapping_pa_to_va((uintptr_t)get_pte_virt_fixmap);
+	pt_ops.alloc_pte = kernel_mapping_pa_to_va(alloc_pte_fixmap);
+	pt_ops.get_pte_virt = kernel_mapping_pa_to_va(get_pte_virt_fixmap);
 #ifndef __PAGETABLE_PMD_FOLDED
-	pt_ops.alloc_pmd = kernel_mapping_pa_to_va((uintptr_t)alloc_pmd_fixmap);
-	pt_ops.get_pmd_virt = kernel_mapping_pa_to_va((uintptr_t)get_pmd_virt_fixmap);
-	pt_ops.alloc_pud = kernel_mapping_pa_to_va((uintptr_t)alloc_pud_fixmap);
-	pt_ops.get_pud_virt = kernel_mapping_pa_to_va((uintptr_t)get_pud_virt_fixmap);
-	pt_ops.alloc_p4d = kernel_mapping_pa_to_va((uintptr_t)alloc_p4d_fixmap);
-	pt_ops.get_p4d_virt = kernel_mapping_pa_to_va((uintptr_t)get_p4d_virt_fixmap);
+	pt_ops.alloc_pmd = kernel_mapping_pa_to_va(alloc_pmd_fixmap);
+	pt_ops.get_pmd_virt = kernel_mapping_pa_to_va(get_pmd_virt_fixmap);
+	pt_ops.alloc_pud = kernel_mapping_pa_to_va(alloc_pud_fixmap);
+	pt_ops.get_pud_virt = kernel_mapping_pa_to_va(get_pud_virt_fixmap);
+	pt_ops.alloc_p4d = kernel_mapping_pa_to_va(alloc_p4d_fixmap);
+	pt_ops.get_p4d_virt = kernel_mapping_pa_to_va(get_p4d_virt_fixmap);
 #endif
 }
 
-- 
2.37.4


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Re: [PATCH v2 1/2] riscv: Fix crash during early errata patching

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Sat, 26 Nov 2022 00:09:19 -0600 you wrote:
> The patch function for the T-Head PBMT errata calls __pa_symbol() before
> relocation. This crashes when CONFIG_DEBUG_VIRTUAL is enabled, because
> __pa_symbol() forwards to __phys_addr_symbol(), and __phys_addr_symbol()
> checks against the absolute kernel start/end address.
> 
> Fix this by checking against the kernel map instead of a symbol address.
> 
> [...]

Here is the summary with links:
  - [v2,1/2] riscv: Fix crash during early errata patching
    https://git.kernel.org/riscv/c/61b2f0bdaa3c
  - [v2,2/2] riscv: Move cast inside kernel_mapping_[pv]a_to_[vp]a
    https://git.kernel.org/riscv/c/583286e2072e

You are awesome, thank you!
-- 
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