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@...> Reviewed-by: Philipp Tomsich <philipp.tomsich@...>
Patch-Comment
arch/riscv/errata/sifive/errata.c | 14 +++++++++----- arch/riscv/include/asm/alternative.h | 3 +++ arch/riscv/kernel/alternative.c | 18 +++++++++++++---- arch/riscv/kernel/module.c | 29 ++++++++++++++++++++++++++++ 4 files changed, 55 insertions(+), 9 deletions(-)
Statistics
- 55 lines added
- 9 lines removed
Changes
---------------------- arch/riscv/errata/sifive/errata.c -----------------------
index 4fe03ac41fd7..3e39587a49dc 100644
@@ -4,6 +4,7 @@
*/
#include <linux/kernel.h>
+#include <linux/module.h>
#include <linux/string.h>
#include <linux/bug.h>
#include <asm/patch.h>
@@ -54,7 +55,8 @@ static struct errata_info_t errata_list[ERRATA_SIFIVE_NUMBER] = {
},
};
+static u32 __init_or_module sifive_errata_probe(unsigned long archid,
+ unsigned long impid)
{
int idx;
u32 cpu_req_errata = 0;
@@ -66,7 +68,7 @@ static u32 __init sifive_errata_probe(unsigned long archid, unsigned long impid)
return cpu_req_errata;
}
+static void __init_or_module warn_miss_errata(u32 miss_errata)
{
int i;
@@ -79,9 +81,11 @@ static void __init warn_miss_errata(u32 miss_errata)
pr_warn("----------------------------------------------------------------\n");
}
+void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
+ struct alt_entry *end,
+ unsigned long archid,
+ unsigned long impid,
+ unsigned int stage)
{
struct alt_entry *alt;
u32 cpu_req_errata = sifive_errata_probe(archid, impid);
--------------------- arch/riscv/include/asm/alternative.h ---------------------
index 0ff550667e94..0859529ff08e 100644
@@ -20,8 +20,10 @@
#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 */
@@ -43,6 +45,7 @@ void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
#else /* CONFIG_RISCV_ALTERNATIVE */
static inline void apply_boot_alternatives(void) { }
+static inline void apply_module_alternatives(void *start, size_t length) { }
#endif /* CONFIG_RISCV_ALTERNATIVE */
----------------------- arch/riscv/kernel/alternative.c ------------------------
index 02db62f55bac..223770b3945c 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>
@@ -23,7 +24,7 @@ static struct cpu_manufacturer_info_t {
static void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end,
unsigned long archid, unsigned long impid,
+ unsigned int stage) __initdata_or_module;
static inline void __init riscv_fill_cpu_mfr_info(void)
{
@@ -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 c29cef90d1dd..91fe16bfaa07 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>
/*
@@ -427,3 +428,31 @@ 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;
+}