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arm64: Move patching utilities out of instruction encoding/decoding

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Files insn.[c|h] containt some functions used for instruction patching.
In order to reuse the instruction encoder/decoder, move the patching
utilities to their own file.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-2-jthierry@redhat.com
[will: Include patching.h in insn.h to fix header mess; add __ASSEMBLY__ guards]
Signed-off-by: Will Deacon <will@kernel.org>

Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Julien Thierry 2021-03-03 18:05:29 +01:00 committed by Will Deacon
parent c4681547bc
commit 5f154c4e20
5 changed files with 168 additions and 152 deletions
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6
arch/arm64/include/asm/insn.h
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@ -11,6 +11,7 @@
#include <linux/types.h>
#include <asm/alternative.h>
#include <asm/patching.h>
#ifndef __ASSEMBLY__
/*
@ -379,8 +380,6 @@ static inline bool aarch64_insn_is_adr_adrp(u32 insn)
return aarch64_insn_is_adr(insn) || aarch64_insn_is_adrp(insn);
}
int aarch64_insn_read(void *addr, u32 *insnp);
int aarch64_insn_write(void *addr, u32 insn);
enum aarch64_insn_encoding_class aarch64_get_insn_class(u32 insn);
bool aarch64_insn_uses_literal(u32 insn);
bool aarch64_insn_is_branch(u32 insn);
@ -487,9 +486,6 @@ u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base,
s32 aarch64_get_branch_offset(u32 insn);
u32 aarch64_set_branch_offset(u32 insn, s32 offset);
int aarch64_insn_patch_text_nosync(void *addr, u32 insn);
int aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt);
s32 aarch64_insn_adrp_get_offset(u32 insn);
u32 aarch64_insn_adrp_set_offset(u32 insn, s32 offset);

15
arch/arm64/include/asm/patching.h Normal file
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@ -0,0 +1,15 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef __ASM_PATCHING_H
#define __ASM_PATCHING_H
#include <linux/types.h>
#ifndef __ASSEMBLY__
int aarch64_insn_read(void *addr, u32 *insnp);
int aarch64_insn_write(void *addr, u32 insn);
int aarch64_insn_patch_text_nosync(void *addr, u32 insn);
int aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt);
#endif /* __ASSEMBLY__ */
#endif /* __ASM_PATCHING_H */

2
arch/arm64/kernel/Makefile
View File

@ -22,7 +22,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \
return_address.o cpuinfo.o cpu_errata.o \
cpufeature.o alternative.o cacheinfo.o \
smp.o smp_spin_table.o topology.o smccc-call.o \
syscall.o proton-pack.o idreg-override.o
syscall.o proton-pack.o idreg-override.o patching.o
targets += efi-entry.o

149
arch/arm64/kernel/insn.c
View File

@ -7,21 +7,14 @@
*/
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/stop_machine.h>
#include <linux/printk.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/debug-monitors.h>
#include <asm/fixmap.h>
#include <asm/errno.h>
#include <asm/insn.h>
#include <asm/kprobes.h>
#include <asm/sections.h>
#define AARCH64_INSN_SF_BIT BIT(31)
#define AARCH64_INSN_N_BIT BIT(22)
@ -83,81 +76,6 @@ bool aarch64_insn_is_branch_imm(u32 insn)
aarch64_insn_is_bcond(insn));
}
static DEFINE_RAW_SPINLOCK(patch_lock);
static bool is_exit_text(unsigned long addr)
{
/* discarded with init text/data */
return system_state < SYSTEM_RUNNING &&
addr >= (unsigned long)__exittext_begin &&
addr < (unsigned long)__exittext_end;
}
static bool is_image_text(unsigned long addr)
{
return core_kernel_text(addr) || is_exit_text(addr);
}
static void __kprobes *patch_map(void *addr, int fixmap)
{
unsigned long uintaddr = (uintptr_t) addr;
bool image = is_image_text(uintaddr);
struct page *page;
if (image)
page = phys_to_page(__pa_symbol(addr));
else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
page = vmalloc_to_page(addr);
else
return addr;
BUG_ON(!page);
return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
(uintaddr & ~PAGE_MASK));
}
static void __kprobes patch_unmap(int fixmap)
{
clear_fixmap(fixmap);
}
/*
* In ARMv8-A, A64 instructions have a fixed length of 32 bits and are always
* little-endian.
*/
int __kprobes aarch64_insn_read(void *addr, u32 *insnp)
{
int ret;
__le32 val;
ret = copy_from_kernel_nofault(&val, addr, AARCH64_INSN_SIZE);
if (!ret)
*insnp = le32_to_cpu(val);
return ret;
}
static int __kprobes __aarch64_insn_write(void *addr, __le32 insn)
{
void *waddr = addr;
unsigned long flags = 0;
int ret;
raw_spin_lock_irqsave(&patch_lock, flags);
waddr = patch_map(addr, FIX_TEXT_POKE0);
ret = copy_to_kernel_nofault(waddr, &insn, AARCH64_INSN_SIZE);
patch_unmap(FIX_TEXT_POKE0);
raw_spin_unlock_irqrestore(&patch_lock, flags);
return ret;
}
int __kprobes aarch64_insn_write(void *addr, u32 insn)
{
return __aarch64_insn_write(addr, cpu_to_le32(insn));
}
bool __kprobes aarch64_insn_uses_literal(u32 insn)
{
/* ldr/ldrsw (literal), prfm */
@ -187,67 +105,6 @@ bool __kprobes aarch64_insn_is_branch(u32 insn)
aarch64_insn_is_bcond(insn);
}
int __kprobes aarch64_insn_patch_text_nosync(void *addr, u32 insn)
{
u32 *tp = addr;
int ret;
/* A64 instructions must be word aligned */
if ((uintptr_t)tp & 0x3)
return -EINVAL;
ret = aarch64_insn_write(tp, insn);
if (ret == 0)
__flush_icache_range((uintptr_t)tp,
(uintptr_t)tp + AARCH64_INSN_SIZE);
return ret;
}
struct aarch64_insn_patch {
void **text_addrs;
u32 *new_insns;
int insn_cnt;
atomic_t cpu_count;
};
static int __kprobes aarch64_insn_patch_text_cb(void *arg)
{
int i, ret = 0;
struct aarch64_insn_patch *pp = arg;
/* The first CPU becomes master */
if (atomic_inc_return(&pp->cpu_count) == 1) {
for (i = 0; ret == 0 && i < pp->insn_cnt; i++)
ret = aarch64_insn_patch_text_nosync(pp->text_addrs[i],
pp->new_insns[i]);
/* Notify other processors with an additional increment. */
atomic_inc(&pp->cpu_count);
} else {
while (atomic_read(&pp->cpu_count) <= num_online_cpus())
cpu_relax();
isb();
}
return ret;
}
int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt)
{
struct aarch64_insn_patch patch = {
.text_addrs = addrs,
.new_insns = insns,
.insn_cnt = cnt,
.cpu_count = ATOMIC_INIT(0),
};
if (cnt <= 0)
return -EINVAL;
return stop_machine_cpuslocked(aarch64_insn_patch_text_cb, &patch,
cpu_online_mask);
}
static int __kprobes aarch64_get_imm_shift_mask(enum aarch64_insn_imm_type type,
u32 *maskp, int *shiftp)
{

148
arch/arm64/kernel/patching.c Normal file
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@ -0,0 +1,148 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/stop_machine.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
#include <asm/kprobes.h>
#include <asm/sections.h>
static DEFINE_RAW_SPINLOCK(patch_lock);
static bool is_exit_text(unsigned long addr)
{
/* discarded with init text/data */
return system_state < SYSTEM_RUNNING &&
addr >= (unsigned long)__exittext_begin &&
addr < (unsigned long)__exittext_end;
}
static bool is_image_text(unsigned long addr)
{
return core_kernel_text(addr) || is_exit_text(addr);
}
static void __kprobes *patch_map(void *addr, int fixmap)
{
unsigned long uintaddr = (uintptr_t) addr;
bool image = is_image_text(uintaddr);
struct page *page;
if (image)
page = phys_to_page(__pa_symbol(addr));
else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
page = vmalloc_to_page(addr);
else
return addr;
BUG_ON(!page);
return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
(uintaddr & ~PAGE_MASK));
}
static void __kprobes patch_unmap(int fixmap)
{
clear_fixmap(fixmap);
}
/*
* In ARMv8-A, A64 instructions have a fixed length of 32 bits and are always
* little-endian.
*/
int __kprobes aarch64_insn_read(void *addr, u32 *insnp)
{
int ret;
__le32 val;
ret = copy_from_kernel_nofault(&val, addr, AARCH64_INSN_SIZE);
if (!ret)
*insnp = le32_to_cpu(val);
return ret;
}
static int __kprobes __aarch64_insn_write(void *addr, __le32 insn)
{
void *waddr = addr;
unsigned long flags = 0;
int ret;
raw_spin_lock_irqsave(&patch_lock, flags);
waddr = patch_map(addr, FIX_TEXT_POKE0);
ret = copy_to_kernel_nofault(waddr, &insn, AARCH64_INSN_SIZE);
patch_unmap(FIX_TEXT_POKE0);
raw_spin_unlock_irqrestore(&patch_lock, flags);
return ret;
}
int __kprobes aarch64_insn_write(void *addr, u32 insn)
{
return __aarch64_insn_write(addr, cpu_to_le32(insn));
}
int __kprobes aarch64_insn_patch_text_nosync(void *addr, u32 insn)
{
u32 *tp = addr;
int ret;
/* A64 instructions must be word aligned */
if ((uintptr_t)tp & 0x3)
return -EINVAL;
ret = aarch64_insn_write(tp, insn);
if (ret == 0)
__flush_icache_range((uintptr_t)tp,
(uintptr_t)tp + AARCH64_INSN_SIZE);
return ret;
}
struct aarch64_insn_patch {
void **text_addrs;
u32 *new_insns;
int insn_cnt;
atomic_t cpu_count;
};
static int __kprobes aarch64_insn_patch_text_cb(void *arg)
{
int i, ret = 0;
struct aarch64_insn_patch *pp = arg;
/* The first CPU becomes master */
if (atomic_inc_return(&pp->cpu_count) == 1) {
for (i = 0; ret == 0 && i < pp->insn_cnt; i++)
ret = aarch64_insn_patch_text_nosync(pp->text_addrs[i],
pp->new_insns[i]);
/* Notify other processors with an additional increment. */
atomic_inc(&pp->cpu_count);
} else {
while (atomic_read(&pp->cpu_count) <= num_online_cpus())
cpu_relax();
isb();
}
return ret;
}
int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt)
{
struct aarch64_insn_patch patch = {
.text_addrs = addrs,
.new_insns = insns,
.insn_cnt = cnt,
.cpu_count = ATOMIC_INIT(0),
};
if (cnt <= 0)
return -EINVAL;
return stop_machine_cpuslocked(aarch64_insn_patch_text_cb, &patch,
cpu_online_mask);
}