Commit 411781a2 authored by Michael Ellerman's avatar Michael Ellerman Committed by Paul Mackerras
Browse files

powerpc: Add new code patching routines 



This commit adds some new routines for patching code, which will be used
in a following commit.

Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 07630a37

arch/powerpc/lib/code-patching.c

+107 −0
Original line number Diff line number Diff line
@@ -41,3 +41,110 @@ unsigned int create_branch(const unsigned int *addr, 


	return instruction;

}



unsigned int create_cond_branch(const unsigned int *addr,

				unsigned long target, int flags)

{

	unsigned int instruction;

	long offset;



	offset = target;

	if (! (flags & BRANCH_ABSOLUTE))

		offset = offset - (unsigned long)addr;



	/* Check we can represent the target in the instruction format */

	if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)

		return 0;



	/* Mask out the flags and target, so they don't step on each other. */

	instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);



	return instruction;

}



static unsigned int branch_opcode(unsigned int instr)

{

	return (instr >> 26) & 0x3F;

}



static int instr_is_branch_iform(unsigned int instr)

{

	return branch_opcode(instr) == 18;

}



static int instr_is_branch_bform(unsigned int instr)

{

	return branch_opcode(instr) == 16;

}



int instr_is_relative_branch(unsigned int instr)

{

	if (instr & BRANCH_ABSOLUTE)

		return 0;



	return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);

}



static unsigned long branch_iform_target(const unsigned int *instr)

{

	signed long imm;



	imm = *instr & 0x3FFFFFC;



	/* If the top bit of the immediate value is set this is negative */

	if (imm & 0x2000000)

		imm -= 0x4000000;



	if ((*instr & BRANCH_ABSOLUTE) == 0)

		imm += (unsigned long)instr;



	return (unsigned long)imm;

}



static unsigned long branch_bform_target(const unsigned int *instr)

{

	signed long imm;



	imm = *instr & 0xFFFC;



	/* If the top bit of the immediate value is set this is negative */

	if (imm & 0x8000)

		imm -= 0x10000;



	if ((*instr & BRANCH_ABSOLUTE) == 0)

		imm += (unsigned long)instr;



	return (unsigned long)imm;

}



unsigned long branch_target(const unsigned int *instr)

{

	if (instr_is_branch_iform(*instr))

		return branch_iform_target(instr);

	else if (instr_is_branch_bform(*instr))

		return branch_bform_target(instr);



	return 0;

}



int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)

{

	if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))

		return branch_target(instr) == addr;



	return 0;

}



unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)

{

	unsigned long target;



	target = branch_target(src);



	if (instr_is_branch_iform(*src))

		return create_branch(dest, target, *src);

	else if (instr_is_branch_bform(*src))

		return create_cond_branch(dest, target, *src);



	return 0;

}

include/asm-powerpc/code-patching.h

+8 −0
Original line number Diff line number Diff line
@@ -23,9 +23,17 @@ 


unsigned int create_branch(const unsigned int *addr,

			   unsigned long target, int flags);

unsigned int create_cond_branch(const unsigned int *addr,

				unsigned long target, int flags);

void patch_branch(unsigned int *addr, unsigned long target, int flags);

void patch_instruction(unsigned int *addr, unsigned int instr);



int instr_is_relative_branch(unsigned int instr);

int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);

unsigned long branch_target(const unsigned int *instr);

unsigned int translate_branch(const unsigned int *dest,

			      const unsigned int *src);



static inline unsigned long ppc_function_entry(void *func)

{

#ifdef CONFIG_PPC64