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Commit ae0dc736 authored by Michael Ellerman's avatar Michael Ellerman Committed by Paul Mackerras
Browse files

powerpc: Add tests of the code patching routines 



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: default avatarMichael Ellerman <michael@ellerman.id.au>
Acked-by: default avatarKumar Gala <galak@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 411781a2

arch/powerpc/Kconfig.debug

+5 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/lib/code-patching.c

+298 −0
Original line number Diff line number Diff line
@@ -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>
@@ -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 */