Unverified Commit a8e91016 authored by Heiko Stuebner's avatar Heiko Stuebner Committed by Palmer Dabbelt
Browse files

riscv: implement module alternatives 



This allows alternatives to also be applied when loading modules
and follows the implementation of other architectures (e.g. arm64).

Signed-off-by: default avatarHeiko Stuebner <heiko@sntech.de>
Reviewed-by: default avatarPhilipp Tomsich <philipp.tomsich@vrull.eu>
Link: https://lore.kernel.org/r/20220511192921.2223629-4-heiko@sntech.de


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent d14ca1f8

arch/riscv/errata/sifive/errata.c

+9 −5
Original line number Diff line number Diff line
@@ -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 sifive_errata_probe(unsigned long archid, unsigned long impid)

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 warn_miss_errata(u32 miss_errata)

static void __init_or_module warn_miss_errata(u32 miss_errata)

{

	int i;
@@ -79,8 +81,10 @@ static void __init warn_miss_errata(u32 miss_errata) 
	pr_warn("----------------------------------------------------------------\n");

}



void __init sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,

				     unsigned long archid, unsigned long impid,

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;

arch/riscv/include/asm/alternative.h

+3 −0
Original line number Diff line number Diff line
@@ -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

+14 −4
Original line number Diff line number Diff line
@@ -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;

				 unsigned int stage) __initdata_or_module;



static inline void __init riscv_fill_cpu_mfr_info(void)

{
@@ -58,7 +59,7 @@ static void __init init_alternative(void) 
 * a feature detect on the boot CPU). No need to worry about other CPUs

 * here.

 */

static void __init _apply_alternatives(struct alt_entry *begin,

static void __init_or_module _apply_alternatives(struct alt_entry *begin,

						 struct alt_entry *end,

						 unsigned int stage)

{
@@ -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

+29 −0
Original line number Diff line number Diff line
@@ -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;

}