Commit ba27d1a8 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/ibt,paravirt: Use text_gen_insn() for paravirt_patch() 



Less duplication is more better.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.697253958@infradead.org
parent bbf92368

arch/x86/include/asm/text-patching.h

+14 −6
Original line number Diff line number Diff line
@@ -96,32 +96,40 @@ union text_poke_insn { 
};



static __always_inline

void *text_gen_insn(u8 opcode, const void *addr, const void *dest)

void __text_gen_insn(void *buf, u8 opcode, const void *addr, const void *dest, int size)

{

	static union text_poke_insn insn; /* per instance */

	int size = text_opcode_size(opcode);

	union text_poke_insn *insn = buf;



	BUG_ON(size < text_opcode_size(opcode));



	/*

	 * Hide the addresses to avoid the compiler folding in constants when

	 * referencing code, these can mess up annotations like

	 * ANNOTATE_NOENDBR.

	 */

	OPTIMIZER_HIDE_VAR(insn);

	OPTIMIZER_HIDE_VAR(addr);

	OPTIMIZER_HIDE_VAR(dest);



	insn.opcode = opcode;

	insn->opcode = opcode;



	if (size > 1) {

		insn.disp = (long)dest - (long)(addr + size);

		insn->disp = (long)dest - (long)(addr + size);

		if (size == 2) {

			/*

			 * Ensure that for JMP8 the displacement

			 * actually fits the signed byte.

			 */

			BUG_ON((insn.disp >> 31) != (insn.disp >> 7));

			BUG_ON((insn->disp >> 31) != (insn->disp >> 7));

		}

	}

}



static __always_inline

void *text_gen_insn(u8 opcode, const void *addr, const void *dest)

{

	static union text_poke_insn insn; /* per instance */

	__text_gen_insn(&insn, opcode, addr, dest, text_opcode_size(opcode));

	return &insn.text;

}

arch/x86/kernel/paravirt.c

+3 −20
Original line number Diff line number Diff line
@@ -69,29 +69,12 @@ noinstr void paravirt_BUG(void) 
	BUG();

}



struct branch {

	unsigned char opcode;

	u32 delta;

} __attribute__((packed));



static unsigned paravirt_patch_call(void *insn_buff, const void *target,

				    unsigned long addr, unsigned len)

{

	const int call_len = 5;

	struct branch *b = insn_buff;

	unsigned long delta = (unsigned long)target - (addr+call_len);



	if (len < call_len) {

		pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);

		/* Kernel might not be viable if patching fails, bail out: */

		BUG_ON(1);

	}



	b->opcode = 0xe8; /* call */

	b->delta = delta;

	BUILD_BUG_ON(sizeof(*b) != call_len);



	return call_len;

	__text_gen_insn(insn_buff, CALL_INSN_OPCODE,

			(void *)addr, target, CALL_INSN_SIZE);

	return CALL_INSN_SIZE;

}



#ifdef CONFIG_PARAVIRT_XXL