[PATCH v3 2/3] riscv: Introduce set_kernel_memory helper

Alexandre Ghiti
2021-06-03T08:30:30Z

This helper should be used for setting permissions to the kernel
mapping as it takes pointers as arguments and then avoids explicit cast
to unsigned long needed for the set_memory_* API.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
arch/riscv/include/asm/set_memory.h | 5 +++++
arch/riscv/mm/pageattr.c | 10 ++++++++++
2 files changed, 15 insertions(+)

diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index 086f757e8ba3..7a411fed9e0e 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -16,6 +16,7 @@ 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);
+int set_kernel_memory(char *start, char *end, int (*set_memory)(unsigned long, int));
void protect_kernel_text_data(void);
#else
static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
@@ -24,6 +25,10 @@ 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 *start, char *end, int (*set_memory)(unsigned long, int))
+{
+ return 0;
+}
#endif

#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 5e49e4b4a4cc..c47ac6a432ac 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -156,6 +156,16 @@ int set_memory_nx(unsigned long addr, int numpages)
return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
}

+int set_kernel_memory(char *startp, char *endp,
+ int (*set_memory)(unsigned long start, int num_pages))
+{
+ unsigned long start = (unsigned long)startp;
+ unsigned long end = (unsigned long)endp;
+ int num_pages = PAGE_ALIGN(end - start) >> PAGE_SHIFT;
+
+ return set_memory(start, num_pages);
+}
+
int set_direct_map_invalid_noflush(struct page *page)
{
int ret;
--
2.30.2