2021-06-17 16:06:51

by Alexandre Ghiti

Subject: [PATCH v6 1/2] riscv: Introduce set_kernel_memory helper

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 <[email protected]>
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Anup Patel <[email protected]>
---
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 9d4d455726d4..59f242abe969 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

2021-06-21 15:02:57

by Christoph Hellwig

Subject: Re: [PATCH v6 1/2] riscv: Introduce set_kernel_memory helper

On Thu, Jun 17, 2021 at 03:17:33PM +0200, Alexandre Ghiti wrote:
> +int set_kernel_memory(char *start, char *end, int (*set_memory)(unsigned long, int));

Pretty unreadable with the crazy long line and the missing parameter
names for the callback. It probably is worth to implement this as
__always_inline so that the compiler unwinds the indirect call.