eccfab069f
MSM implements CONFIG_RWX and disallows the kernel text to be written. However, in cases where we temporarily need to write the kernel text, we explicitly mark it writeable for a short period of time. Change-Id: I532b663a9bd0115ea5e7177e9dac4ac54e007725 Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
84 lines
1.8 KiB
C
84 lines
1.8 KiB
C
#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/stop_machine.h>
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#include <asm/cacheflush.h>
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#include <asm/smp_plat.h>
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#include <asm/opcodes.h>
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#include <asm/mmu_writeable.h>
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#include "patch.h"
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struct patch {
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void *addr;
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unsigned int insn;
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};
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void __kprobes __patch_text(void *addr, unsigned int insn)
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{
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bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
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int size;
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unsigned long flags;
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mem_text_writeable_spinlock(&flags);
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mem_text_address_writeable((unsigned long)addr);
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if (thumb2 && __opcode_is_thumb16(insn)) {
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*(u16 *)addr = __opcode_to_mem_thumb16(insn);
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size = sizeof(u16);
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} else if (thumb2 && ((uintptr_t)addr & 2)) {
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u16 first = __opcode_thumb32_first(insn);
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u16 second = __opcode_thumb32_second(insn);
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u16 *addrh = addr;
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addrh[0] = __opcode_to_mem_thumb16(first);
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addrh[1] = __opcode_to_mem_thumb16(second);
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size = sizeof(u32);
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} else {
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if (thumb2)
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insn = __opcode_to_mem_thumb32(insn);
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else
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insn = __opcode_to_mem_arm(insn);
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*(u32 *)addr = insn;
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size = sizeof(u32);
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}
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flush_icache_range((uintptr_t)(addr),
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(uintptr_t)(addr) + size);
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mem_text_address_restore();
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mem_text_writeable_spinunlock(&flags);
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}
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static int __kprobes patch_text_stop_machine(void *data)
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{
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struct patch *patch = data;
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__patch_text(patch->addr, patch->insn);
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return 0;
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}
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void __kprobes patch_text(void *addr, unsigned int insn)
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{
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struct patch patch = {
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.addr = addr,
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.insn = insn,
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};
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if (cache_ops_need_broadcast()) {
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stop_machine(patch_text_stop_machine, &patch, cpu_online_mask);
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} else {
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bool straddles_word = IS_ENABLED(CONFIG_THUMB2_KERNEL)
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&& __opcode_is_thumb32(insn)
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&& ((uintptr_t)addr & 2);
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if (straddles_word)
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stop_machine(patch_text_stop_machine, &patch, NULL);
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else
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__patch_text(addr, insn);
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}
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}
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