Re: [PATCH v4 11/16] x86/kprobes: Convert to text-patching.h

[Masami Hiramatsu <mhiramat@kernel.org>]

Hi Peter,

On Fri, 18 Oct 2019 09:35:36 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> Convert kprobes to the new text-poke naming.
> 

Looks good to me :)

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks,

> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  arch/x86/include/asm/kprobes.h       |   14 +++--------
>  arch/x86/include/asm/text-patching.h |    2 +
>  arch/x86/kernel/kprobes/core.c       |   18 +++++++-------
>  arch/x86/kernel/kprobes/opt.c        |   44 ++++++++++++++++-------------------
>  4 files changed, 37 insertions(+), 41 deletions(-)
> 
> --- a/arch/x86/include/asm/kprobes.h
> +++ b/arch/x86/include/asm/kprobes.h
> @@ -11,12 +11,11 @@
>  
>  #include <asm-generic/kprobes.h>
>  
> -#define BREAKPOINT_INSTRUCTION	0xcc
> -
>  #ifdef CONFIG_KPROBES
>  #include <linux/types.h>
>  #include <linux/ptrace.h>
>  #include <linux/percpu.h>
> +#include <asm/text-patching.h>
>  #include <asm/insn.h>
>  
>  #define  __ARCH_WANT_KPROBES_INSN_SLOT
> @@ -25,10 +24,7 @@ struct pt_regs;
>  struct kprobe;
>  
>  typedef u8 kprobe_opcode_t;
> -#define RELATIVEJUMP_OPCODE 0xe9
> -#define RELATIVEJUMP_SIZE 5
> -#define RELATIVECALL_OPCODE 0xe8
> -#define RELATIVE_ADDR_SIZE 4
> +
>  #define MAX_STACK_SIZE 64
>  #define CUR_STACK_SIZE(ADDR) \
>  	(current_top_of_stack() - (unsigned long)(ADDR))
> @@ -43,11 +39,11 @@ extern __visible kprobe_opcode_t optprob
>  extern __visible kprobe_opcode_t optprobe_template_val[];
>  extern __visible kprobe_opcode_t optprobe_template_call[];
>  extern __visible kprobe_opcode_t optprobe_template_end[];
> -#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + RELATIVE_ADDR_SIZE)
> +#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + DISP32_SIZE)
>  #define MAX_OPTINSN_SIZE 				\
>  	(((unsigned long)optprobe_template_end -	\
>  	  (unsigned long)optprobe_template_entry) +	\
> -	 MAX_OPTIMIZED_LENGTH + RELATIVEJUMP_SIZE)
> +	 MAX_OPTIMIZED_LENGTH + JMP32_INSN_SIZE)
>  
>  extern const int kretprobe_blacklist_size;
>  
> @@ -73,7 +69,7 @@ struct arch_specific_insn {
>  
>  struct arch_optimized_insn {
>  	/* copy of the original instructions */
> -	kprobe_opcode_t copied_insn[RELATIVE_ADDR_SIZE];
> +	kprobe_opcode_t copied_insn[DISP32_SIZE];
>  	/* detour code buffer */
>  	kprobe_opcode_t *insn;
>  	/* the size of instructions copied to detour code buffer */
> --- a/arch/x86/include/asm/text-patching.h
> +++ b/arch/x86/include/asm/text-patching.h
> @@ -61,6 +61,8 @@ extern void text_poke_finish(void);
>  #define JMP8_INSN_SIZE		2
>  #define JMP8_INSN_OPCODE	0xEB
>  
> +#define DISP32_SIZE		4
> +
>  static inline int text_opcode_size(u8 opcode)
>  {
>  	int size = 0;
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -119,14 +119,14 @@ __synthesize_relative_insn(void *dest, v
>  /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
>  void synthesize_reljump(void *dest, void *from, void *to)
>  {
> -	__synthesize_relative_insn(dest, from, to, RELATIVEJUMP_OPCODE);
> +	__synthesize_relative_insn(dest, from, to, JMP32_INSN_OPCODE);
>  }
>  NOKPROBE_SYMBOL(synthesize_reljump);
>  
>  /* Insert a call instruction at address 'from', which calls address 'to'.*/
>  void synthesize_relcall(void *dest, void *from, void *to)
>  {
> -	__synthesize_relative_insn(dest, from, to, RELATIVECALL_OPCODE);
> +	__synthesize_relative_insn(dest, from, to, CALL_INSN_OPCODE);
>  }
>  NOKPROBE_SYMBOL(synthesize_relcall);
>  
> @@ -301,7 +301,7 @@ static int can_probe(unsigned long paddr
>  		 * Another debugging subsystem might insert this breakpoint.
>  		 * In that case, we can't recover it.
>  		 */
> -		if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
> +		if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
>  			return 0;
>  		addr += insn.length;
>  	}
> @@ -352,7 +352,7 @@ int __copy_instruction(u8 *dest, u8 *src
>  	insn_get_length(insn);
>  
>  	/* Another subsystem puts a breakpoint, failed to recover */
> -	if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
> +	if (insn->opcode.bytes[0] == INT3_INSN_OPCODE)
>  		return 0;
>  
>  	/* We should not singlestep on the exception masking instructions */
> @@ -396,14 +396,14 @@ static int prepare_boost(kprobe_opcode_t
>  	int len = insn->length;
>  
>  	if (can_boost(insn, p->addr) &&
> -	    MAX_INSN_SIZE - len >= RELATIVEJUMP_SIZE) {
> +	    MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) {
>  		/*
>  		 * These instructions can be executed directly if it
>  		 * jumps back to correct address.
>  		 */
>  		synthesize_reljump(buf + len, p->ainsn.insn + len,
>  				   p->addr + insn->length);
> -		len += RELATIVEJUMP_SIZE;
> +		len += JMP32_INSN_SIZE;
>  		p->ainsn.boostable = true;
>  	} else {
>  		p->ainsn.boostable = false;
> @@ -497,7 +497,7 @@ int arch_prepare_kprobe(struct kprobe *p
>  
>  void arch_arm_kprobe(struct kprobe *p)
>  {
> -	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
> +	text_poke(p->addr, ((unsigned char []){INT3_INSN_OPCODE}), 1);
>  }
>  
>  void arch_disarm_kprobe(struct kprobe *p)
> @@ -605,7 +605,7 @@ static void setup_singlestep(struct kpro
>  	regs->flags |= X86_EFLAGS_TF;
>  	regs->flags &= ~X86_EFLAGS_IF;
>  	/* single step inline if the instruction is an int3 */
> -	if (p->opcode == BREAKPOINT_INSTRUCTION)
> +	if (p->opcode == INT3_INSN_OPCODE)
>  		regs->ip = (unsigned long)p->addr;
>  	else
>  		regs->ip = (unsigned long)p->ainsn.insn;
> @@ -691,7 +691,7 @@ int kprobe_int3_handler(struct pt_regs *
>  				reset_current_kprobe();
>  			return 1;
>  		}
> -	} else if (*addr != BREAKPOINT_INSTRUCTION) {
> +	} else if (*addr != INT3_INSN_OPCODE) {
>  		/*
>  		 * The breakpoint instruction was removed right
>  		 * after we hit it.  Another cpu has removed
> --- a/arch/x86/kernel/kprobes/opt.c
> +++ b/arch/x86/kernel/kprobes/opt.c
> @@ -38,7 +38,7 @@ unsigned long __recover_optprobed_insn(k
>  	long offs;
>  	int i;
>  
> -	for (i = 0; i < RELATIVEJUMP_SIZE; i++) {
> +	for (i = 0; i < JMP32_INSN_SIZE; i++) {
>  		kp = get_kprobe((void *)addr - i);
>  		/* This function only handles jump-optimized kprobe */
>  		if (kp && kprobe_optimized(kp)) {
> @@ -62,10 +62,10 @@ unsigned long __recover_optprobed_insn(k
>  
>  	if (addr == (unsigned long)kp->addr) {
>  		buf[0] = kp->opcode;
> -		memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
> +		memcpy(buf + 1, op->optinsn.copied_insn, DISP32_SIZE);
>  	} else {
>  		offs = addr - (unsigned long)kp->addr - 1;
> -		memcpy(buf, op->optinsn.copied_insn + offs, RELATIVE_ADDR_SIZE - offs);
> +		memcpy(buf, op->optinsn.copied_insn + offs, DISP32_SIZE - offs);
>  	}
>  
>  	return (unsigned long)buf;
> @@ -141,8 +141,6 @@ STACK_FRAME_NON_STANDARD(optprobe_templa
>  #define TMPL_END_IDX \
>  	((long)optprobe_template_end - (long)optprobe_template_entry)
>  
> -#define INT3_SIZE sizeof(kprobe_opcode_t)
> -
>  /* Optimized kprobe call back function: called from optinsn */
>  static void
>  optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
> @@ -162,7 +160,7 @@ optimized_callback(struct optimized_kpro
>  		regs->cs |= get_kernel_rpl();
>  		regs->gs = 0;
>  #endif
> -		regs->ip = (unsigned long)op->kp.addr + INT3_SIZE;
> +		regs->ip = (unsigned long)op->kp.addr + INT3_INSN_SIZE;
>  		regs->orig_ax = ~0UL;
>  
>  		__this_cpu_write(current_kprobe, &op->kp);
> @@ -179,7 +177,7 @@ static int copy_optimized_instructions(u
>  	struct insn insn;
>  	int len = 0, ret;
>  
> -	while (len < RELATIVEJUMP_SIZE) {
> +	while (len < JMP32_INSN_SIZE) {
>  		ret = __copy_instruction(dest + len, src + len, real + len, &insn);
>  		if (!ret || !can_boost(&insn, src + len))
>  			return -EINVAL;
> @@ -271,7 +269,7 @@ static int can_optimize(unsigned long pa
>  		return 0;
>  
>  	/* Check there is enough space for a relative jump. */
> -	if (size - offset < RELATIVEJUMP_SIZE)
> +	if (size - offset < JMP32_INSN_SIZE)
>  		return 0;
>  
>  	/* Decode instructions */
> @@ -290,15 +288,15 @@ static int can_optimize(unsigned long pa
>  		kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
>  		insn_get_length(&insn);
>  		/* Another subsystem puts a breakpoint */
> -		if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
> +		if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
>  			return 0;
>  		/* Recover address */
>  		insn.kaddr = (void *)addr;
>  		insn.next_byte = (void *)(addr + insn.length);
>  		/* Check any instructions don't jump into target */
>  		if (insn_is_indirect_jump(&insn) ||
> -		    insn_jump_into_range(&insn, paddr + INT3_SIZE,
> -					 RELATIVE_ADDR_SIZE))
> +		    insn_jump_into_range(&insn, paddr + INT3_INSN_SIZE,
> +					 DISP32_SIZE))
>  			return 0;
>  		addr += insn.length;
>  	}
> @@ -374,7 +372,7 @@ int arch_prepare_optimized_kprobe(struct
>  	 * Verify if the address gap is in 2GB range, because this uses
>  	 * a relative jump.
>  	 */
> -	rel = (long)slot - (long)op->kp.addr + RELATIVEJUMP_SIZE;
> +	rel = (long)slot - (long)op->kp.addr + JMP32_INSN_SIZE;
>  	if (abs(rel) > 0x7fffffff) {
>  		ret = -ERANGE;
>  		goto err;
> @@ -401,7 +399,7 @@ int arch_prepare_optimized_kprobe(struct
>  	/* Set returning jmp instruction at the tail of out-of-line buffer */
>  	synthesize_reljump(buf + len, slot + len,
>  			   (u8 *)op->kp.addr + op->optinsn.size);
> -	len += RELATIVEJUMP_SIZE;
> +	len += JMP32_INSN_SIZE;
>  
>  	/* We have to use text_poke() for instruction buffer because it is RO */
>  	text_poke(slot, buf, len);
> @@ -422,22 +420,22 @@ int arch_prepare_optimized_kprobe(struct
>  void arch_optimize_kprobes(struct list_head *oplist)
>  {
>  	struct optimized_kprobe *op, *tmp;
> -	u8 insn_buff[RELATIVEJUMP_SIZE];
> +	u8 insn_buff[JMP32_INSN_SIZE];
>  
>  	list_for_each_entry_safe(op, tmp, oplist, list) {
>  		s32 rel = (s32)((long)op->optinsn.insn -
> -			((long)op->kp.addr + RELATIVEJUMP_SIZE));
> +			((long)op->kp.addr + JMP32_INSN_SIZE));
>  
>  		WARN_ON(kprobe_disabled(&op->kp));
>  
>  		/* Backup instructions which will be replaced by jump address */
> -		memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE,
> -		       RELATIVE_ADDR_SIZE);
> +		memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_INSN_SIZE,
> +		       DISP32_SIZE);
>  
> -		insn_buff[0] = RELATIVEJUMP_OPCODE;
> +		insn_buff[0] = JMP32_INSN_OPCODE;
>  		*(s32 *)(&insn_buff[1]) = rel;
>  
> -		text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE, NULL);
> +		text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE, NULL);
>  
>  		list_del_init(&op->list);
>  	}
> @@ -446,13 +444,13 @@ void arch_optimize_kprobes(struct list_h
>  /* Replace a relative jump with a breakpoint (int3).  */
>  void arch_unoptimize_kprobe(struct optimized_kprobe *op)
>  {
> -	u8 insn_buff[RELATIVEJUMP_SIZE];
> +	u8 insn_buff[JMP32_INSN_SIZE];
>  
>  	/* Set int3 to first byte for kprobes */
> -	insn_buff[0] = BREAKPOINT_INSTRUCTION;
> -	memcpy(insn_buff + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
> +	insn_buff[0] = INT3_INSN_OPCODE;
> +	memcpy(insn_buff + 1, op->optinsn.copied_insn, DISP32_SIZE);
>  
> -	text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE,
> +	text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE,
>  		     text_gen_insn(JMP32_INSN_OPCODE, op->kp.addr, op->optinsn.insn));
>  }
>  
> 
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>