/* * Copyright 2008 Michael Ellerman, IBM Corporation. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include int patch_instruction(unsigned int *addr, unsigned int instr) { int err; __put_user_size(instr, addr, 4, err); if (err) return err; asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr)); return 0; } int patch_branch(unsigned int *addr, unsigned long target, int flags) { return patch_instruction(addr, create_branch(addr, target, flags)); } unsigned int create_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 < -0x2000000 || offset > 0x1fffffc || offset & 0x3) return 0; /* Mask out the flags and target, so they don't step on each other. */ instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC); 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; } #ifdef CONFIG_PPC_BOOK3E_64 void __patch_exception(int exc, unsigned long addr) { extern unsigned int interrupt_base_book3e; unsigned int *ibase = &interrupt_base_book3e; /* Our exceptions vectors start with a NOP and -then- a branch * to deal with single stepping from userspace which stops on * the second instruction. Thus we need to patch the second * instruction of the exception, not the first one */ patch_branch(ibase + (exc / 4) + 1, addr, 0); } #endif #ifdef CONFIG_CODE_PATCHING_SELFTEST static void __init test_trampoline(void) { asm ("nop;\n"); } #define check(x) \ if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__); static void __init test_branch_iform(void) { unsigned int instr; unsigned long addr; addr = (unsigned long)&instr; /* The simplest case, branch to self, no flags */ check(instr_is_branch_iform(0x48000000)); /* All bits of target set, and flags */ check(instr_is_branch_iform(0x4bffffff)); /* High bit of opcode set, which is wrong */ check(!instr_is_branch_iform(0xcbffffff)); /* Middle bits of opcode set, which is wrong */ check(!instr_is_branch_iform(0x7bffffff)); /* Simplest case, branch to self with link */ check(instr_is_branch_iform(0x48000001)); /* All bits of targets set */ check(instr_is_branch_iform(0x4bfffffd)); /* Some bits of targets set */ check(instr_is_branch_iform(0x4bff00fd)); /* Must be a valid branch to start with */ check(!instr_is_branch_iform(0x7bfffffd)); /* Absolute branch to 0x100 */ instr = 0x48000103; check(instr_is_branch_to_addr(&instr, 0x100)); /* Absolute branch to 0x420fc */ instr = 0x480420ff; check(instr_is_branch_to_addr(&instr, 0x420fc)); /* Maximum positive relative branch, + 20MB - 4B */ instr = 0x49fffffc; check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC)); /* Smallest negative relative branch, - 4B */ instr = 0x4bfffffc; check(instr_is_branch_to_addr(&instr, addr - 4)); /* Largest negative relative branch, - 32 MB */ instr = 0x4a000000; check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); /* Branch to self, with link */ instr = create_branch(&instr, addr, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr)); /* Branch to self - 0x100, with link */ instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr - 0x100)); /* Branch to self + 0x100, no link */ instr = create_branch(&instr, addr + 0x100, 0); check(instr_is_branch_to_addr(&instr, addr + 0x100)); /* Maximum relative negative offset, - 32 MB */ instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK); check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); /* Out of range relative negative offset, - 32 MB + 4*/ instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK); check(instr == 0); /* Out of range relative positive offset, + 32 MB */ instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK); check(instr == 0); /* Unaligned target */ instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK); check(instr == 0); /* Check flags are masked correctly */ instr = create_branch(&instr, addr, 0xFFFFFFFC); check(instr_is_branch_to_addr(&instr, addr)); check(instr == 0x48000000); } static void __init test_create_function_call(void) { unsigned int *iptr; unsigned long dest; /* Check we can create a function call */ iptr = (unsigned int *)ppc_function_entry(test_trampoline); dest = ppc_function_entry(test_create_function_call); patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK)); check(instr_is_branch_to_addr(iptr, dest)); } static void __init test_branch_bform(void) { unsigned long addr; unsigned int *iptr, instr, flags; iptr = &instr; addr = (unsigned long)iptr; /* The simplest case, branch to self, no flags */ check(instr_is_branch_bform(0x40000000)); /* All bits of target set, and flags */ check(instr_is_branch_bform(0x43ffffff)); /* High bit of opcode set, which is wrong */ check(!instr_is_branch_bform(0xc3ffffff)); /* Middle bits of opcode set, which is wrong */ check(!instr_is_branch_bform(0x7bffffff)); /* Absolute conditional branch to 0x100 */ instr = 0x43ff0103; check(instr_is_branch_to_addr(&instr, 0x100)); /* Absolute conditional branch to 0x20fc */ instr = 0x43ff20ff; check(instr_is_branch_to_addr(&instr, 0x20fc)); /* Maximum positive relative conditional branch, + 32 KB - 4B */ instr = 0x43ff7ffc; check(instr_is_branch_to_addr(&instr, addr + 0x7FFC)); /* Smallest negative relative conditional branch, - 4B */ instr = 0x43fffffc; check(instr_is_branch_to_addr(&instr, addr - 4)); /* Largest negative relative conditional branch, - 32 KB */ instr = 0x43ff8000; check(instr_is_branch_to_addr(&instr, addr - 0x8000)); /* All condition code bits set & link */ flags = 0x3ff000 | BRANCH_SET_LINK; /* Branch to self */ instr = create_cond_branch(iptr, addr, flags); check(instr_is_branch_to_addr(&instr, addr)); /* Branch to self - 0x100 */ instr = create_cond_branch(iptr, addr - 0x100, flags); check(instr_is_branch_to_addr(&instr, addr - 0x100)); /* Branch to self + 0x100 */ instr = create_cond_branch(iptr, addr + 0x100, flags); check(instr_is_branch_to_addr(&instr, addr + 0x100)); /* Maximum relative negative offset, - 32 KB */ instr = create_cond_branch(iptr, addr - 0x8000, flags); check(instr_is_branch_to_addr(&instr, addr - 0x8000)); /* Out of range relative negative offset, - 32 KB + 4*/ instr = create_cond_branch(iptr, addr - 0x8004, flags); check(instr == 0); /* Out of range relative positive offset, + 32 KB */ instr = create_cond_branch(iptr, addr + 0x8000, flags); check(instr == 0); /* Unaligned target */ instr = create_cond_branch(iptr, addr + 3, flags); check(instr == 0); /* Check flags are masked correctly */ instr = create_cond_branch(iptr, addr, 0xFFFFFFFC); check(instr_is_branch_to_addr(&instr, addr)); check(instr == 0x43FF0000); } static void __init test_translate_branch(void) { unsigned long addr; unsigned int *p, *q; void *buf; buf = vmalloc(PAGE_ALIGN(0x2000000 + 1)); check(buf); if (!buf) return; /* Simple case, branch to self moved a little */ p = buf; addr = (unsigned long)p; patch_branch(p, addr, 0); check(instr_is_branch_to_addr(p, addr)); q = p + 1; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(q, addr)); /* Maximum negative case, move b . to addr + 32 MB */ p = buf; addr = (unsigned long)p; patch_branch(p, addr, 0); q = buf + 0x2000000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x4a000000); /* Maximum positive case, move x to x - 32 MB + 4 */ p = buf + 0x2000000; addr = (unsigned long)p; patch_branch(p, addr, 0); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x49fffffc); /* Jump to x + 16 MB moved to x + 20 MB */ p = buf; addr = 0x1000000 + (unsigned long)buf; patch_branch(p, addr, BRANCH_SET_LINK); q = buf + 0x1400000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Jump to x + 16 MB moved to x - 16 MB + 4 */ p = buf + 0x1000000; addr = 0x2000000 + (unsigned long)buf; patch_branch(p, addr, 0); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Conditional branch tests */ /* Simple case, branch to self moved a little */ p = buf; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0)); check(instr_is_branch_to_addr(p, addr)); q = p + 1; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(q, addr)); /* Maximum negative case, move b . to addr + 32 KB */ p = buf; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); q = buf + 0x8000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x43ff8000); /* Maximum positive case, move x to x - 32 KB + 4 */ p = buf + 0x8000; addr = (unsigned long)p; patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); check(*q == 0x43ff7ffc); /* Jump to x + 12 KB moved to x + 20 KB */ p = buf; addr = 0x3000 + (unsigned long)buf; patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK)); q = buf + 0x5000; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Jump to x + 8 KB moved to x - 8 KB + 4 */ p = buf + 0x2000; addr = 0x4000 + (unsigned long)buf; patch_instruction(p, create_cond_branch(p, addr, 0)); q = buf + 4; patch_instruction(q, translate_branch(q, p)); check(instr_is_branch_to_addr(p, addr)); check(instr_is_branch_to_addr(q, addr)); /* Free the buffer we were using */ vfree(buf); } static int __init test_code_patching(void) { printk(KERN_DEBUG "Running code patching self-tests ...\n"); test_branch_iform(); test_branch_bform(); test_create_function_call(); test_translate_branch(); return 0; } late_initcall(test_code_patching); #endif /* CONFIG_CODE_PATCHING_SELFTEST */