riscv: implement module alternatives
From: Heiko Stuebner <heiko@...> Date: Thu, 9 Dec 2021 18:04:40 +0100
Commit-Message
This allows alternatives to also be applied when loading modules and follows the implementation of other architectures (e.g. arm64). Signed-off-by: Heiko Stuebner <heiko@...>
Patch-Comment
arch/riscv/include/asm/alternative.h | 3 ++- arch/riscv/kernel/alternative.c | 16 ++++++++++++--- arch/riscv/kernel/module.c | 29 ++++++++++++++++++++++++++++ 3 files changed, 44 insertions(+), 4 deletions(-)
Statistics
- 44 lines added
- 4 lines removed
Changes
--------------------- arch/riscv/include/asm/alternative.h ---------------------
index 811bdd8027db..f0657b1b3174 100644
@@ -18,8 +18,10 @@
#include <asm/hwcap.h>
#define RISCV_ALTERNATIVES_BOOT 0 /* alternatives applied during regular boot */
+#define RISCV_ALTERNATIVES_MODULE 1 /* alternatives applied during module-init */
void __init apply_boot_alternatives(void);
+void apply_module_alternatives(void *start, size_t length);
struct alt_entry {
void *old_ptr; /* address of original instruciton or data */
@@ -37,6 +39,5 @@ struct errata_checkfunc_id {
void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
unsigned long archid, unsigned long impid,
unsigned int stage);
#endif
#endif
----------------------- arch/riscv/kernel/alternative.c ------------------------
index ead00c508266..e1849faa2fa1 100644
@@ -7,6 +7,7 @@
*/
#include <linux/init.h>
+#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <asm/alternative.h>
@@ -58,9 +59,9 @@ static void __init init_alternative(void)
* a feature detect on the boot CPU). No need to worry about other CPUs
* here.
*/
+static void __init_or_module _apply_alternatives(struct alt_entry *begin,
+ struct alt_entry *end,
+ unsigned int stage)
{
if (!vendor_patch_func)
return;
@@ -81,3 +82,12 @@ void __init apply_boot_alternatives(void)
(struct alt_entry *)__alt_end,
RISCV_ALTERNATIVES_BOOT);
}
+
+#ifdef CONFIG_MODULES
+void apply_module_alternatives(void *start, size_t length)
+{
+ _apply_alternatives((struct alt_entry *)start,
+ (struct alt_entry *)(start + length),
+ RISCV_ALTERNATIVES_MODULE);
+}
+#endif
-------------------------- arch/riscv/kernel/module.c --------------------------
index 68a9e3d1fe16..a778abd5b8b9 100644
@@ -11,6 +11,7 @@
#include <linux/vmalloc.h>
#include <linux/sizes.h>
#include <linux/pgtable.h>
+#include <asm/alternative.h>
#include <asm/sections.h>
static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v)
@@ -416,3 +417,31 @@ void *module_alloc(unsigned long size)
__builtin_return_address(0));
}
#endif
+
+static const Elf_Shdr *find_section(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs,
+ const char *name)
+{
+ const Elf_Shdr *s, *se;
+ const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+ for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
+ if (strcmp(name, secstrs + s->sh_name) == 0)
+ return s;
+ }
+
+ return NULL;
+}
+
+int module_finalize(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs,
+ struct module *me)
+{
+ const Elf_Shdr *s;
+
+ s = find_section(hdr, sechdrs, ".alternative");
+ if (s)
+ apply_module_alternatives((void *)s->sh_addr, s->sh_size);
+
+ return 0;
+}