[RFC PATCH v0 10/19] x86/kprobes: Convert to insn_decode()

Borislav Petkov
2020-11-24T10:20:25Z

Simplify code, no functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/kprobes/core.c | 17 +++++++++++------
arch/x86/kernel/kprobes/opt.c | 9 +++++++--
2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 547c7abb39f5..43d4a3056d21 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -285,6 +285,8 @@ static int can_probe(unsigned long paddr)
/* Decode instructions */
addr = paddr - offset;
while (addr < paddr) {
+ int ret;
+
/*
* Check if the instruction has been modified by another
* kprobe, in which case we replace the breakpoint by the
@@ -296,8 +298,10 @@ static int can_probe(unsigned long paddr)
__addr = recover_probed_instruction(buf, addr);
if (!__addr)
return 0;
- kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);
- insn_get_length(&insn);
+
+ ret = insn_decode(&insn, (void *)__addr, MAX_INSN_SIZE, INSN_MODE_KERN);
+ if (ret < 0)
+ return 0;

/*
* Another debugging subsystem might insert this breakpoint.
@@ -340,8 +344,8 @@ static int is_IF_modifier(kprobe_opcode_t *insn)
int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
{
kprobe_opcode_t buf[MAX_INSN_SIZE];
- unsigned long recovered_insn =
- recover_probed_instruction(buf, (unsigned long)src);
+ unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src);
+ int ret;

if (!recovered_insn || !insn)
return 0;
@@ -351,8 +355,9 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
MAX_INSN_SIZE))
return 0;

- kernel_insn_init(insn, dest, MAX_INSN_SIZE);
- insn_get_length(insn);
+ ret = insn_decode(insn, dest, MAX_INSN_SIZE, INSN_MODE_KERN);
+ if (ret < 0)
+ return 0;

/* We can not probe force emulate prefixed instruction */
if (insn_has_emulate_prefix(insn))
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 041f0b50bc27..4d67571249e1 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -299,6 +299,8 @@ static int can_optimize(unsigned long paddr)
addr = paddr - offset;
while (addr < paddr - offset + size) { /* Decode until function end */
unsigned long recovered_insn;
+ int ret;
+
if (search_exception_tables(addr))
/*
* Since some fixup code will jumps into this function,
@@ -308,8 +310,11 @@ static int can_optimize(unsigned long paddr)
recovered_insn = recover_probed_instruction(buf, addr);
if (!recovered_insn)
return 0;
- kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
- insn_get_length(&insn);
+
+ ret = insn_decode(&insn, (void *)recovered_insn, MAX_INSN_SIZE, INSN_MODE_KERN);
+ if (ret < 0)
+ return 0;
+
/* Another subsystem puts a breakpoint */
if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
return 0;
--
2.21.0