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linux/arch/powerpc/lib/test-code-patching.c
Christophe Leroy 309a0a6018 powerpc/code-patching: Replace patch_instruction() by ppc_inst_write() in selftests 
The purpose of selftests is to check that instructions are
properly formed. Not to check that they properly run.

For that test it uses normal memory, not special test
memory.

In preparation of a future patch enforcing patch_instruction()
to be used only on valid text areas, implement a ppc_inst_write()
instruction which is the complement of ppc_inst_read(). This
new function writes the formated instruction in valid kernel
memory and doesn't bother about icache.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7cf5335cc07ca9b6f8cdaa20ca9887fce4df3bea.1638446239.git.christophe.leroy@csgroup.eu
2021-12-23 22:36:58 +11:00

363 lines
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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);
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