Commit c5ef5e35 authored by Benjamin Gray's avatar Benjamin Gray Committed by Michael Ellerman
Browse files

powerpc/code-patching: Test patch_instructions() during boot 



patch_instructions() introduces new behaviour with a couple of
variations. Test each case of

  * a repeated 32-bit instruction,
  * a repeated 64-bit instruction (ppc64), and
  * a copied sequence of instructions

for both on a single page and when it crosses a page boundary.

Signed-off-by: default avatarBenjamin Gray <bgray@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240325052815.854044-1-bgray@linux.ibm.com
parent 295454ed

arch/powerpc/lib/test-code-patching.c

+92 −0
Original line number Diff line number Diff line
@@ -347,6 +347,97 @@ static void __init test_prefixed_patching(void) 
	check(!memcmp(iptr, expected, sizeof(expected)));

}



static void __init test_multi_instruction_patching(void)

{

	u32 code[32];

	void *buf;

	u32 *addr32;

	u64 *addr64;

	ppc_inst_t inst64 = ppc_inst_prefix(OP_PREFIX << 26 | 3UL << 24, PPC_RAW_TRAP());

	u32 inst32 = PPC_RAW_NOP();



	buf = vzalloc(PAGE_SIZE * 8);

	check(buf);

	if (!buf)

		return;



	/* Test single page 32-bit repeated instruction */

	addr32 = buf + PAGE_SIZE;

	check(!patch_instructions(addr32 + 1, &inst32, 12, true));



	check(addr32[0] == 0);

	check(addr32[1] == inst32);

	check(addr32[2] == inst32);

	check(addr32[3] == inst32);

	check(addr32[4] == 0);



	/* Test single page 64-bit repeated instruction */

	if (IS_ENABLED(CONFIG_PPC64)) {

		check(ppc_inst_prefixed(inst64));



		addr64 = buf + PAGE_SIZE * 2;

		ppc_inst_write(code, inst64);

		check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));



		check(addr64[0] == 0);

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[1]), inst64));

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[2]), inst64));

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[3]), inst64));

		check(addr64[4] == 0);

	}



	/* Test single page memcpy */

	addr32 = buf + PAGE_SIZE * 3;



	for (int i = 0; i < ARRAY_SIZE(code); i++)

		code[i] = i + 1;



	check(!patch_instructions(addr32 + 1, code, sizeof(code), false));



	check(addr32[0] == 0);

	check(!memcmp(&addr32[1], code, sizeof(code)));

	check(addr32[ARRAY_SIZE(code) + 1] == 0);



	/* Test multipage 32-bit repeated instruction */

	addr32 = buf + PAGE_SIZE * 4 - 8;

	check(!patch_instructions(addr32 + 1, &inst32, 12, true));



	check(addr32[0] == 0);

	check(addr32[1] == inst32);

	check(addr32[2] == inst32);

	check(addr32[3] == inst32);

	check(addr32[4] == 0);



	/* Test multipage 64-bit repeated instruction */

	if (IS_ENABLED(CONFIG_PPC64)) {

		check(ppc_inst_prefixed(inst64));



		addr64 = buf + PAGE_SIZE * 5 - 8;

		ppc_inst_write(code, inst64);

		check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));



		check(addr64[0] == 0);

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[1]), inst64));

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[2]), inst64));

		check(ppc_inst_equal(ppc_inst_read((u32 *)&addr64[3]), inst64));

		check(addr64[4] == 0);

	}



	/* Test multipage memcpy */

	addr32 = buf + PAGE_SIZE * 6 - 12;



	for (int i = 0; i < ARRAY_SIZE(code); i++)

		code[i] = i + 1;



	check(!patch_instructions(addr32 + 1, code, sizeof(code), false));



	check(addr32[0] == 0);

	check(!memcmp(&addr32[1], code, sizeof(code)));

	check(addr32[ARRAY_SIZE(code) + 1] == 0);



	vfree(buf);

}



static int __init test_code_patching(void)

{

	pr_info("Running code patching self-tests ...\n");
@@ -356,6 +447,7 @@ static int __init test_code_patching(void) 
	test_create_function_call();

	test_translate_branch();

	test_prefixed_patching();

	test_multi_instruction_patching();



	return 0;

}