riscv: Map the kernel with correct permissions the first time

For 64-bit kernels, we map all the kernel with write and execute
permissions and afterwards remove writability from text and executability
from data.

For 32-bit kernels, the kernel mapping resides in the linear mapping, so we
map all the linear mapping as writable and executable and afterwards we
remove those properties for unused memory and kernel mapping as
described above.

Change this behavior to directly map the kernel with correct permissions
and avoid going through the whole mapping to fix the permissions.

At the same time, this fixes an issue introduced by commit 2bfc6cd81bd1
("riscv: Move kernel mapping outside of linear mapping") as reported
here https://github.com/starfive-tech/linux/issues/17.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

3 files changed, 29 insertions, 9 deletions

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 6e004d8fda4d..349e4f9874cc 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -95,6 +95,7 @@ extern unsigned long va_kernel_pa_offset;
 #endif
 extern unsigned long va_kernel_xip_pa_offset;
 extern unsigned long pfn_base;
+extern uintptr_t load_sz;
 #define ARCH_PFN_OFFSET		(pfn_base)
 #else
 #define va_pa_offset		0
@@ -108,6 +109,11 @@ extern unsigned long pfn_base;
 extern unsigned long kernel_virt_addr;
 
 #ifdef CONFIG_64BIT
+#define is_kernel_mapping(x)	\
+	((x) >= kernel_virt_addr && (x) < (kernel_virt_addr + load_sz))
+#define is_linear_mapping(x)	\
+	((x) >= PAGE_OFFSET && (x) < kernel_virt_addr)
+
 #define linear_mapping_pa_to_va(x)	((void *)((unsigned long)(x) + va_pa_offset))
 #define kernel_mapping_pa_to_va(y)	({						\
 	unsigned long _y = y;								\
@@ -127,10 +133,15 @@ extern unsigned long kernel_virt_addr;
 
 #define __va_to_pa_nodebug(x)	({						\
 	unsigned long _x = x;							\
-	(_x < kernel_virt_addr) ?						\
+	is_linear_mapping(_x) ?							\
 		linear_mapping_va_to_pa(_x) : kernel_mapping_va_to_pa(_x);	\
 	})
 #else
+#define is_kernel_mapping(x)	\
+	((x) >= kernel_virt_addr && (x) < (kernel_virt_addr + load_sz))
+#define is_linear_mapping(x)	\
+	((x) >= PAGE_OFFSET)
+
 #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
 #define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
 #endif /* CONFIG_64BIT */
diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h
index 8a303fb1ee3b..32336e8a17cb 100644
--- a/arch/riscv/include/asm/sections.h
+++ b/arch/riscv/include/asm/sections.h
@@ -6,6 +6,7 @@
 #define __ASM_SECTIONS_H
 
 #include <asm-generic/sections.h>
+#include <linux/mm.h>
 
 extern char _start[];
 extern char _start_kernel[];
@@ -13,4 +14,20 @@ extern char __init_data_begin[], __init_data_end[];
 extern char __init_text_begin[], __init_text_end[];
 extern char __alt_start[], __alt_end[];
 
+static inline bool is_va_kernel_text(uintptr_t va)
+{
+	uintptr_t start = (uintptr_t)_start;
+	uintptr_t end = (uintptr_t)__init_data_begin;
+
+	return va >= start && va < end;
+}
+
+static inline bool is_va_kernel_lm_alias_text(uintptr_t va)
+{
+	uintptr_t start = (uintptr_t)lm_alias(_start);
+	uintptr_t end = (uintptr_t)lm_alias(__init_data_begin);
+
+	return va >= start && va < end;
+}
+
 #endif /* __ASM_SECTIONS_H */
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index 135f726c4c1d..a2c14d4b3993 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -16,7 +16,6 @@ int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
 int set_memory_rw_nx(unsigned long addr, int numpages);
-void protect_kernel_text_data(void);
 static __always_inline int set_kernel_memory(char *startp, char *endp,
 					     int (*set_memory)(unsigned long start,
 							       int num_pages))
@@ -32,7 +31,6 @@ static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
-static inline void protect_kernel_text_data(void) {}
 static inline int set_memory_rw_nx(unsigned long addr, int numpages) { return 0; }
 static inline int set_kernel_memory(char *startp, char *endp,
 				    int (*set_memory)(unsigned long start,
@@ -42,12 +40,6 @@ static inline int set_kernel_memory(char *startp, char *endp,
 }
 #endif
 
-#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
-void protect_kernel_linear_mapping_text_rodata(void);
-#else
-static inline void protect_kernel_linear_mapping_text_rodata(void) {}
-#endif
-
 int set_direct_map_invalid_noflush(struct page *page);
 int set_direct_map_default_noflush(struct page *page);
 bool kernel_page_present(struct page *page);