From aaddd3eacaeaef3503035750b3f21ac2bfe97cbf Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 24 Jun 2008 11:32:21 +1000 Subject: powerpc: Move code patching code into arch/powerpc/lib/code-patching.c We currently have a few routines for patching code in asm/system.h, because they didn't fit anywhere else. I'd like to clean them up a little and add some more, so first move them into a dedicated C file - they don't need to be inlined. While we're moving the code, drop create_function_call(), it's intended caller never got merged and will be replaced in future with something different. Signed-off-by: Michael Ellerman Acked-by: Kumar Gala Signed-off-by: Paul Mackerras --- arch/powerpc/lib/code-patching.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 arch/powerpc/lib/code-patching.c (limited to 'arch/powerpc/lib/code-patching.c') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c new file mode 100644 index 000000000000..7afae88ed1d4 --- /dev/null +++ b/arch/powerpc/lib/code-patching.c @@ -0,0 +1,33 @@ +/* + * 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 + + +void create_instruction(unsigned long addr, unsigned int instr) +{ + unsigned int *p; + p = (unsigned int *)addr; + *p = instr; + asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (p)); +} + +void create_branch(unsigned long addr, unsigned long target, int flags) +{ + unsigned int instruction; + + if (! (flags & BRANCH_ABSOLUTE)) + target = target - addr; + + /* Mask out the flags and target, so they don't step on each other. */ + instruction = 0x48000000 | (flags & 0x3) | (target & 0x03FFFFFC); + + create_instruction(addr, instruction); +} -- cgit v1.2.3 From e7a57273c6407bb6903fbaddec8c2119bf318617 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 24 Jun 2008 11:32:22 +1000 Subject: powerpc: Allow create_branch() to return errors Currently create_branch() creates a branch instruction for you, and patches it into the call site. In some circumstances it would be nice to be able to create the instruction and patch it later, and also some code might want to check for errors in the branch creation before doing the patching. A future commit will change create_branch() to check for errors. For callers that don't care, replace create_branch() with patch_branch(), which just creates the branch and patches it directly. While we're touching all the callers, change to using unsigned int *, as this seems to match usage better. That allows (and requires) us to remove the volatile in the definition of vector in powermac/smp.c and mpc86xx_smp.c, that's correct because now that we're passing vector as an unsigned int * the compiler knows that it's value might change across the patch_branch() call. Signed-off-by: Michael Ellerman Acked-by: Kumar Gala Acked-by: Jon Loeliger Signed-off-by: Paul Mackerras --- arch/powerpc/lib/code-patching.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'arch/powerpc/lib/code-patching.c') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 7afae88ed1d4..638dde313cbc 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -11,23 +11,27 @@ #include -void create_instruction(unsigned long addr, unsigned int instr) +void patch_instruction(unsigned int *addr, unsigned int instr) { - unsigned int *p; - p = (unsigned int *)addr; - *p = instr; - asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (p)); + *addr = instr; + asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr)); } -void create_branch(unsigned long addr, unsigned long target, int flags) +void patch_branch(unsigned int *addr, unsigned long target, int flags) +{ + patch_instruction(addr, create_branch(addr, target, flags)); +} + +unsigned int create_branch(const unsigned int *addr, + unsigned long target, int flags) { unsigned int instruction; if (! (flags & BRANCH_ABSOLUTE)) - target = target - addr; + target = target - (unsigned long)addr; /* Mask out the flags and target, so they don't step on each other. */ instruction = 0x48000000 | (flags & 0x3) | (target & 0x03FFFFFC); - create_instruction(addr, instruction); + return instruction; } -- cgit v1.2.3 From 053a858efa46c9ab86363b271374ec02ad2af753 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 24 Jun 2008 11:32:24 +1000 Subject: powerpc: Make create_branch() return errors if the branch target is too large If you pass a target value to create_branch() which is more than 32MB - 4, or - 32MB away from the branch site, then it's impossible to create an immediate branch. The current code doesn't check, which will lead to us creating a branch to somewhere else - which is bad. For code that cares to check we return 0, which is easy to check for, and for code that doesn't at least we'll be creating an illegal instruction, rather than a branch to some random address. Signed-off-by: Michael Ellerman Acked-by: Kumar Gala Signed-off-by: Paul Mackerras --- arch/powerpc/lib/code-patching.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/lib/code-patching.c') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 638dde313cbc..430f4c15d786 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -26,12 +26,18 @@ unsigned int create_branch(const unsigned int *addr, unsigned long target, int flags) { unsigned int instruction; + long offset; + offset = target; if (! (flags & BRANCH_ABSOLUTE)) - target = target - (unsigned long)addr; + 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) | (target & 0x03FFFFFC); + instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC); return instruction; } -- cgit v1.2.3 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/code-patching.c') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 430f4c15d786..27957c4ea9e0 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 From ae0dc73625f9b0e636ccd130e394c9b654a062fb Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 24 Jun 2008 11:32:32 +1000 Subject: powerpc: Add tests of the code patching routines Add tests of the existing code patching routines, as well as the new routines added in the last commit. The self-tests are run late in boot when CONFIG_CODE_PATCHING_SELFTEST=y, which depends on DEBUG_KERNEL=y. Signed-off-by: Michael Ellerman Acked-by: Kumar Gala Signed-off-by: Paul Mackerras --- arch/powerpc/lib/code-patching.c | 298 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 298 insertions(+) (limited to 'arch/powerpc/lib/code-patching.c') diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 27957c4ea9e0..0559fe086eb4 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -8,6 +8,9 @@ */ #include +#include +#include +#include #include @@ -148,3 +151,298 @@ unsigned int translate_branch(const unsigned int *dest, const unsigned int *src) return 0; } + + +#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 */ -- cgit v1.2.3