2 * Copyright 2008 Michael Ellerman, IBM Corporation.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
10 #include <linux/kernel.h>
11 #include <linux/vmalloc.h>
12 #include <linux/init.h>
15 #include <asm/code-patching.h>
16 #include <asm/uaccess.h>
19 int patch_instruction(unsigned int *addr, unsigned int instr)
23 __put_user_size(instr, addr, 4, err);
26 asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr));
30 int patch_branch(unsigned int *addr, unsigned long target, int flags)
32 return patch_instruction(addr, create_branch(addr, target, flags));
35 unsigned int create_branch(const unsigned int *addr,
36 unsigned long target, int flags)
38 unsigned int instruction;
42 if (! (flags & BRANCH_ABSOLUTE))
43 offset = offset - (unsigned long)addr;
45 /* Check we can represent the target in the instruction format */
46 if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
49 /* Mask out the flags and target, so they don't step on each other. */
50 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
55 unsigned int create_cond_branch(const unsigned int *addr,
56 unsigned long target, int flags)
58 unsigned int instruction;
62 if (! (flags & BRANCH_ABSOLUTE))
63 offset = offset - (unsigned long)addr;
65 /* Check we can represent the target in the instruction format */
66 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
69 /* Mask out the flags and target, so they don't step on each other. */
70 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
75 static unsigned int branch_opcode(unsigned int instr)
77 return (instr >> 26) & 0x3F;
80 static int instr_is_branch_iform(unsigned int instr)
82 return branch_opcode(instr) == 18;
85 static int instr_is_branch_bform(unsigned int instr)
87 return branch_opcode(instr) == 16;
90 int instr_is_relative_branch(unsigned int instr)
92 if (instr & BRANCH_ABSOLUTE)
95 return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
98 static unsigned long branch_iform_target(const unsigned int *instr)
102 imm = *instr & 0x3FFFFFC;
104 /* If the top bit of the immediate value is set this is negative */
108 if ((*instr & BRANCH_ABSOLUTE) == 0)
109 imm += (unsigned long)instr;
111 return (unsigned long)imm;
114 static unsigned long branch_bform_target(const unsigned int *instr)
118 imm = *instr & 0xFFFC;
120 /* If the top bit of the immediate value is set this is negative */
124 if ((*instr & BRANCH_ABSOLUTE) == 0)
125 imm += (unsigned long)instr;
127 return (unsigned long)imm;
130 unsigned long branch_target(const unsigned int *instr)
132 if (instr_is_branch_iform(*instr))
133 return branch_iform_target(instr);
134 else if (instr_is_branch_bform(*instr))
135 return branch_bform_target(instr);
140 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
142 if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
143 return branch_target(instr) == addr;
148 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
150 unsigned long target;
152 target = branch_target(src);
154 if (instr_is_branch_iform(*src))
155 return create_branch(dest, target, *src);
156 else if (instr_is_branch_bform(*src))
157 return create_cond_branch(dest, target, *src);
163 #ifdef CONFIG_CODE_PATCHING_SELFTEST
165 static void __init test_trampoline(void)
171 if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
173 static void __init test_branch_iform(void)
178 addr = (unsigned long)&instr;
180 /* The simplest case, branch to self, no flags */
181 check(instr_is_branch_iform(0x48000000));
182 /* All bits of target set, and flags */
183 check(instr_is_branch_iform(0x4bffffff));
184 /* High bit of opcode set, which is wrong */
185 check(!instr_is_branch_iform(0xcbffffff));
186 /* Middle bits of opcode set, which is wrong */
187 check(!instr_is_branch_iform(0x7bffffff));
189 /* Simplest case, branch to self with link */
190 check(instr_is_branch_iform(0x48000001));
191 /* All bits of targets set */
192 check(instr_is_branch_iform(0x4bfffffd));
193 /* Some bits of targets set */
194 check(instr_is_branch_iform(0x4bff00fd));
195 /* Must be a valid branch to start with */
196 check(!instr_is_branch_iform(0x7bfffffd));
198 /* Absolute branch to 0x100 */
200 check(instr_is_branch_to_addr(&instr, 0x100));
201 /* Absolute branch to 0x420fc */
203 check(instr_is_branch_to_addr(&instr, 0x420fc));
204 /* Maximum positive relative branch, + 20MB - 4B */
206 check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
207 /* Smallest negative relative branch, - 4B */
209 check(instr_is_branch_to_addr(&instr, addr - 4));
210 /* Largest negative relative branch, - 32 MB */
212 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
214 /* Branch to self, with link */
215 instr = create_branch(&instr, addr, BRANCH_SET_LINK);
216 check(instr_is_branch_to_addr(&instr, addr));
218 /* Branch to self - 0x100, with link */
219 instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
220 check(instr_is_branch_to_addr(&instr, addr - 0x100));
222 /* Branch to self + 0x100, no link */
223 instr = create_branch(&instr, addr + 0x100, 0);
224 check(instr_is_branch_to_addr(&instr, addr + 0x100));
226 /* Maximum relative negative offset, - 32 MB */
227 instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
228 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
230 /* Out of range relative negative offset, - 32 MB + 4*/
231 instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
234 /* Out of range relative positive offset, + 32 MB */
235 instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
238 /* Unaligned target */
239 instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
242 /* Check flags are masked correctly */
243 instr = create_branch(&instr, addr, 0xFFFFFFFC);
244 check(instr_is_branch_to_addr(&instr, addr));
245 check(instr == 0x48000000);
248 static void __init test_create_function_call(void)
253 /* Check we can create a function call */
254 iptr = (unsigned int *)ppc_function_entry(test_trampoline);
255 dest = ppc_function_entry(test_create_function_call);
256 patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
257 check(instr_is_branch_to_addr(iptr, dest));
260 static void __init test_branch_bform(void)
263 unsigned int *iptr, instr, flags;
266 addr = (unsigned long)iptr;
268 /* The simplest case, branch to self, no flags */
269 check(instr_is_branch_bform(0x40000000));
270 /* All bits of target set, and flags */
271 check(instr_is_branch_bform(0x43ffffff));
272 /* High bit of opcode set, which is wrong */
273 check(!instr_is_branch_bform(0xc3ffffff));
274 /* Middle bits of opcode set, which is wrong */
275 check(!instr_is_branch_bform(0x7bffffff));
277 /* Absolute conditional branch to 0x100 */
279 check(instr_is_branch_to_addr(&instr, 0x100));
280 /* Absolute conditional branch to 0x20fc */
282 check(instr_is_branch_to_addr(&instr, 0x20fc));
283 /* Maximum positive relative conditional branch, + 32 KB - 4B */
285 check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
286 /* Smallest negative relative conditional branch, - 4B */
288 check(instr_is_branch_to_addr(&instr, addr - 4));
289 /* Largest negative relative conditional branch, - 32 KB */
291 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
293 /* All condition code bits set & link */
294 flags = 0x3ff000 | BRANCH_SET_LINK;
297 instr = create_cond_branch(iptr, addr, flags);
298 check(instr_is_branch_to_addr(&instr, addr));
300 /* Branch to self - 0x100 */
301 instr = create_cond_branch(iptr, addr - 0x100, flags);
302 check(instr_is_branch_to_addr(&instr, addr - 0x100));
304 /* Branch to self + 0x100 */
305 instr = create_cond_branch(iptr, addr + 0x100, flags);
306 check(instr_is_branch_to_addr(&instr, addr + 0x100));
308 /* Maximum relative negative offset, - 32 KB */
309 instr = create_cond_branch(iptr, addr - 0x8000, flags);
310 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
312 /* Out of range relative negative offset, - 32 KB + 4*/
313 instr = create_cond_branch(iptr, addr - 0x8004, flags);
316 /* Out of range relative positive offset, + 32 KB */
317 instr = create_cond_branch(iptr, addr + 0x8000, flags);
320 /* Unaligned target */
321 instr = create_cond_branch(iptr, addr + 3, flags);
324 /* Check flags are masked correctly */
325 instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
326 check(instr_is_branch_to_addr(&instr, addr));
327 check(instr == 0x43FF0000);
330 static void __init test_translate_branch(void)
336 buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
341 /* Simple case, branch to self moved a little */
343 addr = (unsigned long)p;
344 patch_branch(p, addr, 0);
345 check(instr_is_branch_to_addr(p, addr));
347 patch_instruction(q, translate_branch(q, p));
348 check(instr_is_branch_to_addr(q, addr));
350 /* Maximum negative case, move b . to addr + 32 MB */
352 addr = (unsigned long)p;
353 patch_branch(p, addr, 0);
355 patch_instruction(q, translate_branch(q, p));
356 check(instr_is_branch_to_addr(p, addr));
357 check(instr_is_branch_to_addr(q, addr));
358 check(*q == 0x4a000000);
360 /* Maximum positive case, move x to x - 32 MB + 4 */
362 addr = (unsigned long)p;
363 patch_branch(p, addr, 0);
365 patch_instruction(q, translate_branch(q, p));
366 check(instr_is_branch_to_addr(p, addr));
367 check(instr_is_branch_to_addr(q, addr));
368 check(*q == 0x49fffffc);
370 /* Jump to x + 16 MB moved to x + 20 MB */
372 addr = 0x1000000 + (unsigned long)buf;
373 patch_branch(p, addr, BRANCH_SET_LINK);
375 patch_instruction(q, translate_branch(q, p));
376 check(instr_is_branch_to_addr(p, addr));
377 check(instr_is_branch_to_addr(q, addr));
379 /* Jump to x + 16 MB moved to x - 16 MB + 4 */
381 addr = 0x2000000 + (unsigned long)buf;
382 patch_branch(p, addr, 0);
384 patch_instruction(q, translate_branch(q, p));
385 check(instr_is_branch_to_addr(p, addr));
386 check(instr_is_branch_to_addr(q, addr));
389 /* Conditional branch tests */
391 /* Simple case, branch to self moved a little */
393 addr = (unsigned long)p;
394 patch_instruction(p, create_cond_branch(p, addr, 0));
395 check(instr_is_branch_to_addr(p, addr));
397 patch_instruction(q, translate_branch(q, p));
398 check(instr_is_branch_to_addr(q, addr));
400 /* Maximum negative case, move b . to addr + 32 KB */
402 addr = (unsigned long)p;
403 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
405 patch_instruction(q, translate_branch(q, p));
406 check(instr_is_branch_to_addr(p, addr));
407 check(instr_is_branch_to_addr(q, addr));
408 check(*q == 0x43ff8000);
410 /* Maximum positive case, move x to x - 32 KB + 4 */
412 addr = (unsigned long)p;
413 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
415 patch_instruction(q, translate_branch(q, p));
416 check(instr_is_branch_to_addr(p, addr));
417 check(instr_is_branch_to_addr(q, addr));
418 check(*q == 0x43ff7ffc);
420 /* Jump to x + 12 KB moved to x + 20 KB */
422 addr = 0x3000 + (unsigned long)buf;
423 patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
425 patch_instruction(q, translate_branch(q, p));
426 check(instr_is_branch_to_addr(p, addr));
427 check(instr_is_branch_to_addr(q, addr));
429 /* Jump to x + 8 KB moved to x - 8 KB + 4 */
431 addr = 0x4000 + (unsigned long)buf;
432 patch_instruction(p, create_cond_branch(p, addr, 0));
434 patch_instruction(q, translate_branch(q, p));
435 check(instr_is_branch_to_addr(p, addr));
436 check(instr_is_branch_to_addr(q, addr));
438 /* Free the buffer we were using */
442 static int __init test_code_patching(void)
444 printk(KERN_DEBUG "Running code patching self-tests ...\n");
448 test_create_function_call();
449 test_translate_branch();
453 late_initcall(test_code_patching);
455 #endif /* CONFIG_CODE_PATCHING_SELFTEST */