Commit e4778a0e authored by Jinghao Jia's avatar Jinghao Jia Committed by Masami Hiramatsu (Google)
Browse files

x86/kprobes: Refactor can_{probe,boost} return type to bool 

Both can_probe and can_boost have int return type but are using int as
boolean in their context.

Refactor both functions to make them actually return boolean.

Link: https://lore.kernel.org/all/20240204031300.830475-2-jinghao7@illinois.edu/



Signed-off-by: default avatarJinghao Jia <jinghao7@illinois.edu>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
parent 90d35da6

arch/x86/kernel/kprobes/common.h

+1 −1
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ 
#endif



/* Ensure if the instruction can be boostable */

extern int can_boost(struct insn *insn, void *orig_addr);

extern bool can_boost(struct insn *insn, void *orig_addr);

/* Recover instruction if given address is probed */

extern unsigned long recover_probed_instruction(kprobe_opcode_t *buf,

					 unsigned long addr);

arch/x86/kernel/kprobes/core.c

+15 −18
Original line number Diff line number Diff line
@@ -137,14 +137,14 @@ NOKPROBE_SYMBOL(synthesize_relcall); 
 * Returns non-zero if INSN is boostable.

 * RIP relative instructions are adjusted at copying time in 64 bits mode

 */

int can_boost(struct insn *insn, void *addr)

bool can_boost(struct insn *insn, void *addr)

{

	kprobe_opcode_t opcode;

	insn_byte_t prefix;

	int i;



	if (search_exception_tables((unsigned long)addr))

		return 0;	/* Page fault may occur on this address. */

		return false;	/* Page fault may occur on this address. */



	/* 2nd-byte opcode */

	if (insn->opcode.nbytes == 2)
@@ -152,7 +152,7 @@ int can_boost(struct insn *insn, void *addr) 
				(unsigned long *)twobyte_is_boostable);



	if (insn->opcode.nbytes != 1)

		return 0;

		return false;



	for_each_insn_prefix(insn, i, prefix) {

		insn_attr_t attr;
@@ -160,7 +160,7 @@ int can_boost(struct insn *insn, void *addr) 
		attr = inat_get_opcode_attribute(prefix);

		/* Can't boost Address-size override prefix and CS override prefix */

		if (prefix == 0x2e || inat_is_address_size_prefix(attr))

			return 0;

			return false;

	}



	opcode = insn->opcode.bytes[0];
@@ -181,12 +181,12 @@ int can_boost(struct insn *insn, void *addr) 
	case 0xf6 ... 0xf7:	/* Grp3 */

	case 0xfe:		/* Grp4 */

		/* ... are not boostable */

		return 0;

		return false;

	case 0xff:		/* Grp5 */

		/* Only indirect jmp is boostable */

		return X86_MODRM_REG(insn->modrm.bytes[0]) == 4;

	default:

		return 1;

		return true;

	}

}
@@ -253,20 +253,18 @@ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long add 
}



/* Check if paddr is at an instruction boundary */

static int can_probe(unsigned long paddr)

static bool can_probe(unsigned long paddr)

{

	unsigned long addr, __addr, offset = 0;

	struct insn insn;

	kprobe_opcode_t buf[MAX_INSN_SIZE];



	if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))

		return 0;

		return false;



	/* 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
@@ -277,11 +275,10 @@ static int can_probe(unsigned long paddr) 
		 */

		__addr = recover_probed_instruction(buf, addr);

		if (!__addr)

			return 0;

			return false;



		ret = insn_decode_kernel(&insn, (void *)__addr);

		if (ret < 0)

			return 0;

		if (insn_decode_kernel(&insn, (void *)__addr) < 0)

			return false;



#ifdef CONFIG_KGDB

		/*
@@ -290,7 +287,7 @@ static int can_probe(unsigned long paddr) 
		 */

		if (insn.opcode.bytes[0] == INT3_INSN_OPCODE &&

		    kgdb_has_hit_break(addr))

			return 0;

			return false;

#endif

		addr += insn.length;

	}
@@ -310,10 +307,10 @@ static int can_probe(unsigned long paddr) 
		 */

		__addr = recover_probed_instruction(buf, addr);

		if (!__addr)

			return 0;

			return false;



		if (insn_decode_kernel(&insn, (void *)__addr) < 0)

			return 0;

			return false;



		if (insn.opcode.value == 0xBA)

			offset = 12;
@@ -324,7 +321,7 @@ static int can_probe(unsigned long paddr) 


		/* This movl/addl is used for decoding CFI. */

		if (is_cfi_trap(addr + offset))

			return 0;

			return false;

	}



out: