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powerpc: Add tests of the code patching routines
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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 <michael@ellerman.id.au>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Michael Ellerman authored and Paul Mackerras committed Jul 1, 2008
1 parent 411781a commit ae0dc73
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5 changes: 5 additions & 0 deletions arch/powerpc/Kconfig.debug
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Expand Up @@ -57,6 +57,11 @@ config KGDB
debugger. See <http://kgdb.sourceforge.net/> for more information.
Unless you are intending to debug the kernel, say N here.

config CODE_PATCHING_SELFTEST
bool "Run self-tests of the code-patching code."
depends on DEBUG_KERNEL
default n

choice
prompt "Serial Port"
depends on KGDB
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298 changes: 298 additions & 0 deletions arch/powerpc/lib/code-patching.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,9 @@
*/

#include <linux/kernel.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <asm/page.h>
#include <asm/code-patching.h>


Expand Down Expand Up @@ -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 */

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