From 411781a290b0d0a31fd73826b3ee110f1e3cc3b6 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 24 Jun 2008 11:32:29 +1000 Subject: 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: Michael Ellerman Signed-off-by: Paul Mackerras --- arch/powerpc/lib/code-patching.c | 107 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) (limited to 'arch/powerpc/lib') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 430f4c15d78..27957c4ea9e 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -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; +} -- cgit v1.2.3