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test-code-patching.c
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test-code-patching.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2008 Michael Ellerman, IBM Corporation.
*/
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <asm/code-patching.h>
static int __init instr_is_branch_to_addr(const u32 *instr, unsigned long addr)
{
if (instr_is_branch_iform(ppc_inst_read(instr)) ||
instr_is_branch_bform(ppc_inst_read(instr)))
return branch_target(instr) == addr;
return 0;
}
static void __init test_trampoline(void)
{
asm ("nop;nop;\n");
}
#define check(x) do { \
if (!(x)) \
pr_err("code-patching: test failed at line %d\n", __LINE__); \
} while (0)
static void __init test_branch_iform(void)
{
int err;
ppc_inst_t instr;
u32 tmp[2];
u32 *iptr = tmp;
unsigned long addr = (unsigned long)tmp;
/* The simplest case, branch to self, no flags */
check(instr_is_branch_iform(ppc_inst(0x48000000)));
/* All bits of target set, and flags */
check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
/* High bit of opcode set, which is wrong */
check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
/* Middle bits of opcode set, which is wrong */
check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
/* Simplest case, branch to self with link */
check(instr_is_branch_iform(ppc_inst(0x48000001)));
/* All bits of targets set */
check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
/* Some bits of targets set */
check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
/* Must be a valid branch to start with */
check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
/* Absolute branch to 0x100 */
ppc_inst_write(iptr, ppc_inst(0x48000103));
check(instr_is_branch_to_addr(iptr, 0x100));
/* Absolute branch to 0x420fc */
ppc_inst_write(iptr, ppc_inst(0x480420ff));
check(instr_is_branch_to_addr(iptr, 0x420fc));
/* Maximum positive relative branch, + 20MB - 4B */
ppc_inst_write(iptr, ppc_inst(0x49fffffc));
check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
/* Smallest negative relative branch, - 4B */
ppc_inst_write(iptr, ppc_inst(0x4bfffffc));
check(instr_is_branch_to_addr(iptr, addr - 4));
/* Largest negative relative branch, - 32 MB */
ppc_inst_write(iptr, ppc_inst(0x4a000000));
check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
/* Branch to self, with link */
err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr));
/* Branch to self - 0x100, with link */
err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr - 0x100));
/* Branch to self + 0x100, no link */
err = create_branch(&instr, iptr, addr + 0x100, 0);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr + 0x100));
/* Maximum relative negative offset, - 32 MB */
err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
/* Out of range relative negative offset, - 32 MB + 4*/
err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
check(err);
/* Out of range relative positive offset, + 32 MB */
err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
check(err);
/* Unaligned target */
err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
check(err);
/* Check flags are masked correctly */
err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr));
check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
}
static void __init test_create_function_call(void)
{
u32 *iptr;
unsigned long dest;
ppc_inst_t instr;
/* Check we can create a function call */
iptr = (u32 *)ppc_function_entry(test_trampoline);
dest = ppc_function_entry(test_create_function_call);
create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
patch_instruction(iptr, instr);
check(instr_is_branch_to_addr(iptr, dest));
}
static void __init test_branch_bform(void)
{
int err;
unsigned long addr;
ppc_inst_t instr;
u32 tmp[2];
u32 *iptr = tmp;
unsigned int flags;
addr = (unsigned long)iptr;
/* The simplest case, branch to self, no flags */
check(instr_is_branch_bform(ppc_inst(0x40000000)));
/* All bits of target set, and flags */
check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
/* High bit of opcode set, which is wrong */
check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
/* Middle bits of opcode set, which is wrong */
check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
/* Absolute conditional branch to 0x100 */
ppc_inst_write(iptr, ppc_inst(0x43ff0103));
check(instr_is_branch_to_addr(iptr, 0x100));
/* Absolute conditional branch to 0x20fc */
ppc_inst_write(iptr, ppc_inst(0x43ff20ff));
check(instr_is_branch_to_addr(iptr, 0x20fc));
/* Maximum positive relative conditional branch, + 32 KB - 4B */
ppc_inst_write(iptr, ppc_inst(0x43ff7ffc));
check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
/* Smallest negative relative conditional branch, - 4B */
ppc_inst_write(iptr, ppc_inst(0x43fffffc));
check(instr_is_branch_to_addr(iptr, addr - 4));
/* Largest negative relative conditional branch, - 32 KB */
ppc_inst_write(iptr, ppc_inst(0x43ff8000));
check(instr_is_branch_to_addr(iptr, addr - 0x8000));
/* All condition code bits set & link */
flags = 0x3ff000 | BRANCH_SET_LINK;
/* Branch to self */
err = create_cond_branch(&instr, iptr, addr, flags);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr));
/* Branch to self - 0x100 */
err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr - 0x100));
/* Branch to self + 0x100 */
err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr + 0x100));
/* Maximum relative negative offset, - 32 KB */
err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr - 0x8000));
/* Out of range relative negative offset, - 32 KB + 4*/
err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
check(err);
/* Out of range relative positive offset, + 32 KB */
err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
check(err);
/* Unaligned target */
err = create_cond_branch(&instr, iptr, addr + 3, flags);
check(err);
/* Check flags are masked correctly */
err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
ppc_inst_write(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr));
check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
}
static void __init test_translate_branch(void)
{
unsigned long addr;
void *p, *q;
ppc_inst_t instr;
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;
create_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
check(instr_is_branch_to_addr(p, addr));
q = p + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(q, addr));
/* Maximum negative case, move b . to addr + 32 MB */
p = buf;
addr = (unsigned long)p;
create_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
q = buf + 0x2000000;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
/* Maximum positive case, move x to x - 32 MB + 4 */
p = buf + 0x2000000;
addr = (unsigned long)p;
create_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
/* Jump to x + 16 MB moved to x + 20 MB */
p = buf;
addr = 0x1000000 + (unsigned long)buf;
create_branch(&instr, p, addr, BRANCH_SET_LINK);
ppc_inst_write(p, instr);
q = buf + 0x1400000;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
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;
create_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
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;
create_cond_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
check(instr_is_branch_to_addr(p, addr));
q = buf + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(q, addr));
/* Maximum negative case, move b . to addr + 32 KB */
p = buf;
addr = (unsigned long)p;
create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
ppc_inst_write(p, instr);
q = buf + 0x8000;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
/* Maximum positive case, move x to x - 32 KB + 4 */
p = buf + 0x8000;
addr = (unsigned long)p;
create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
ppc_inst_write(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
/* Jump to x + 12 KB moved to x + 20 KB */
p = buf;
addr = 0x3000 + (unsigned long)buf;
create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
ppc_inst_write(p, instr);
q = buf + 0x5000;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
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;
create_cond_branch(&instr, p, addr, 0);
ppc_inst_write(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
ppc_inst_write(q, instr);
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 void __init test_prefixed_patching(void)
{
u32 *iptr = (u32 *)ppc_function_entry(test_trampoline);
u32 expected[2] = {OP_PREFIX << 26, 0};
ppc_inst_t inst = ppc_inst_prefix(OP_PREFIX << 26, 0);
if (!IS_ENABLED(CONFIG_PPC64))
return;
patch_instruction(iptr, inst);
check(!memcmp(iptr, expected, sizeof(expected)));
}
static int __init test_code_patching(void)
{
pr_info("Running code patching self-tests ...\n");
test_branch_iform();
test_branch_bform();
test_create_function_call();
test_translate_branch();
test_prefixed_patching();
return 0;
}
late_initcall(test_code_patching);