ftrace: make ftrace_test_p6nop disassembler-friendly (8b27386a) · Commits · 戴 / test

Commit 4c3dc21b136f8cb4b72afee16c3ba7e961656c0b in tip introduced the 5-byte NOP ftrace_test_p6nop: jmp . + 5 .byte 0x00, 0x00, 0x00 This is not friendly to disassemblers because an odd number of 0x00s ends in the middle of an instruction boundary. This changes the 0x00s to 1-byte NOPs (0x90). Signed-off-by:

Anders Kaseorg <andersk@mit.edu> Acked-by:

Steven Rostedt <rostedt@goodmis.org> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ftrace.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -132,7 +132,9 @@ int __init ftrace_dyn_arch_init(void *data)
		".section .text, \"ax\"\n"
		"ftrace_test_jmp:"
		"jmp ftrace_test_p6nop\n"
		".byte 0x00,0x00,0x00\n" /* 2 byte jmp + 3 bytes */
		"nop\n"
		"nop\n"
		"nop\n" /* 2 byte jmp + 3 bytes */
		"ftrace_test_p6nop:"
		P6_NOP5
		"jmp 1f\n"
		@@ -161,7 +163,7 @@ int __init ftrace_dyn_arch_init(void *data)
		ftrace_nop = (unsigned long *)ftrace_test_nop5;
		break;
		case 2:
		pr_info("ftrace: converting mcount calls to jmp 1f\n");
		pr_info("ftrace: converting mcount calls to jmp . + 5\n");
		ftrace_nop = (unsigned long *)ftrace_test_jmp;
		break;
		}

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