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Commit 9648dc15 authored by Stephen Boyd's avatar Stephen Boyd Committed by Steven Rostedt
Browse files

recordmcount: arm: Implement make_nop 

In similar spirit to x86 and arm64 support, add a make_nop_arm()
to replace calls to mcount with a nop in sections that aren't
traced.

Link: http://lkml.kernel.org/r/20161018234200.5804-1-sboyd@codeaurora.org



Acked-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Acked-by: default avatarRabin Vincent <rabin@rab.in>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 8d414bd2

scripts/recordmcount.c

+65 −0
Original line number Diff line number Diff line
@@ -213,6 +213,59 @@ static int make_nop_x86(void *map, size_t const offset) 
	return 0;

}



static unsigned char ideal_nop4_arm_le[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */

static unsigned char ideal_nop4_arm_be[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */

static unsigned char *ideal_nop4_arm;



static unsigned char bl_mcount_arm_le[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */

static unsigned char bl_mcount_arm_be[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */

static unsigned char *bl_mcount_arm;



static unsigned char push_arm_le[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */

static unsigned char push_arm_be[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */

static unsigned char *push_arm;



static unsigned char ideal_nop2_thumb_le[2] = { 0x00, 0xbf }; /* nop */

static unsigned char ideal_nop2_thumb_be[2] = { 0xbf, 0x00 }; /* nop */

static unsigned char *ideal_nop2_thumb;



static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */

static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */

static unsigned char *push_bl_mcount_thumb;



static int make_nop_arm(void *map, size_t const offset)

{

	char *ptr;

	int cnt = 1;

	int nop_size;

	size_t off = offset;



	ptr = map + offset;

	if (memcmp(ptr, bl_mcount_arm, 4) == 0) {

		if (memcmp(ptr - 4, push_arm, 4) == 0) {

			off -= 4;

			cnt = 2;

		}

		ideal_nop = ideal_nop4_arm;

		nop_size = 4;

	} else if (memcmp(ptr - 2, push_bl_mcount_thumb, 6) == 0) {

		cnt = 3;

		nop_size = 2;

		off -= 2;

		ideal_nop = ideal_nop2_thumb;

	} else

		return -1;



	/* Convert to nop */

	ulseek(fd_map, off, SEEK_SET);



	do {

		uwrite(fd_map, ideal_nop, nop_size);

	} while (--cnt > 0);



	return 0;

}



static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};

static int make_nop_arm64(void *map, size_t const offset)

{
@@ -430,6 +483,11 @@ do_file(char const *const fname) 
			w2 = w2rev;

			w8 = w8rev;

		}

		ideal_nop4_arm = ideal_nop4_arm_le;

		bl_mcount_arm = bl_mcount_arm_le;

		push_arm = push_arm_le;

		ideal_nop2_thumb = ideal_nop2_thumb_le;

		push_bl_mcount_thumb = push_bl_mcount_thumb_le;

		break;

	case ELFDATA2MSB:

		if (*(unsigned char const *)&endian != 0) {
@@ -438,6 +496,11 @@ do_file(char const *const fname) 
			w2 = w2rev;

			w8 = w8rev;

		}

		ideal_nop4_arm = ideal_nop4_arm_be;

		bl_mcount_arm = bl_mcount_arm_be;

		push_arm = push_arm_be;

		ideal_nop2_thumb = ideal_nop2_thumb_be;

		push_bl_mcount_thumb = push_bl_mcount_thumb_be;

		break;

	}  /* end switch */

	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
@@ -463,6 +526,8 @@ do_file(char const *const fname) 
		break;

	case EM_ARM:	 reltype = R_ARM_ABS32;

			 altmcount = "__gnu_mcount_nc";

			 make_nop = make_nop_arm;

			 rel_type_nop = R_ARM_NONE;

			 break;

	case EM_AARCH64:

			reltype = R_AARCH64_ABS64;