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powerpc/code-patching: Move code patching selftests in its own file
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Code patching selftests are half of code-patching.c.
As they are guarded by CONFIG_CODE_PATCHING_SELFTESTS,
they'd be better in their own file.

Also add a missing __init for instr_is_branch_to_addr()

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c0c30504f04eb546a48ff77127a8bccd12a3d809.1638446239.git.christophe.leroy@csgroup.eu
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Christophe Leroy authored and Michael Ellerman committed Dec 23, 2021
1 parent 31acc59 commit f30a578
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Showing 3 changed files with 359 additions and 355 deletions.
2 changes: 2 additions & 0 deletions arch/powerpc/lib/Makefile
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Expand Up @@ -21,6 +21,8 @@ endif

obj-y += alloc.o code-patching.o feature-fixups.o pmem.o

obj-$(CONFIG_CODE_PATCHING_SELFTEST) += test-code-patching.o

ifndef CONFIG_KASAN
obj-y += string.o memcmp_$(BITS).o
obj-$(CONFIG_PPC32) += strlen_32.o
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355 changes: 0 additions & 355 deletions arch/powerpc/lib/code-patching.c
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Expand Up @@ -3,13 +3,10 @@
* Copyright 2008 Michael Ellerman, IBM Corporation.
*/

#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/cpuhotplug.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#include <asm/tlbflush.h>
Expand Down Expand Up @@ -354,355 +351,3 @@ int translate_branch(ppc_inst_t *instr, const u32 *dest, const u32 *src)

return 1;
}

#ifdef CONFIG_CODE_PATCHING_SELFTEST

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 */
patch_instruction(iptr, ppc_inst(0x48000103));
check(instr_is_branch_to_addr(iptr, 0x100));
/* Absolute branch to 0x420fc */
patch_instruction(iptr, ppc_inst(0x480420ff));
check(instr_is_branch_to_addr(iptr, 0x420fc));
/* Maximum positive relative branch, + 20MB - 4B */
patch_instruction(iptr, ppc_inst(0x49fffffc));
check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
/* Smallest negative relative branch, - 4B */
patch_instruction(iptr, ppc_inst(0x4bfffffc));
check(instr_is_branch_to_addr(iptr, addr - 4));
/* Largest negative relative branch, - 32 MB */
patch_instruction(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);
patch_instruction(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);
patch_instruction(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);
patch_instruction(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);
patch_instruction(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);
patch_instruction(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 */
patch_instruction(iptr, ppc_inst(0x43ff0103));
check(instr_is_branch_to_addr(iptr, 0x100));
/* Absolute conditional branch to 0x20fc */
patch_instruction(iptr, ppc_inst(0x43ff20ff));
check(instr_is_branch_to_addr(iptr, 0x20fc));
/* Maximum positive relative conditional branch, + 32 KB - 4B */
patch_instruction(iptr, ppc_inst(0x43ff7ffc));
check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
/* Smallest negative relative conditional branch, - 4B */
patch_instruction(iptr, ppc_inst(0x43fffffc));
check(instr_is_branch_to_addr(iptr, addr - 4));
/* Largest negative relative conditional branch, - 32 KB */
patch_instruction(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);
patch_instruction(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr));

/* Branch to self - 0x100 */
err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
patch_instruction(iptr, instr);
check(instr_is_branch_to_addr(iptr, addr - 0x100));

/* Branch to self + 0x100 */
err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
patch_instruction(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);
patch_instruction(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);
patch_instruction(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;
patch_branch(p, addr, 0);
check(instr_is_branch_to_addr(p, addr));
q = p + 4;
translate_branch(&instr, q, p);
patch_instruction(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;
patch_branch(p, addr, 0);
q = buf + 0x2000000;
translate_branch(&instr, q, p);
patch_instruction(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;
patch_branch(p, addr, 0);
q = buf + 4;
translate_branch(&instr, q, p);
patch_instruction(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;
patch_branch(p, addr, BRANCH_SET_LINK);
q = buf + 0x1400000;
translate_branch(&instr, q, p);
patch_instruction(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;
patch_branch(p, addr, 0);
q = buf + 4;
translate_branch(&instr, q, p);
patch_instruction(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);
patch_instruction(p, instr);
check(instr_is_branch_to_addr(p, addr));
q = buf + 4;
translate_branch(&instr, q, p);
patch_instruction(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);
patch_instruction(p, instr);
q = buf + 0x8000;
translate_branch(&instr, q, p);
patch_instruction(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);
patch_instruction(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
patch_instruction(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);
patch_instruction(p, instr);
q = buf + 0x5000;
translate_branch(&instr, q, p);
patch_instruction(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);
patch_instruction(p, instr);
q = buf + 4;
translate_branch(&instr, q, p);
patch_instruction(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);

#endif /* CONFIG_CODE_PATCHING_SELFTEST */
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