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Commit 78d9af4c authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes/x86: Cleanup the usage of arch_uprobe->def.fixups, make it u8 



handle_riprel_insn() assumes that nobody else could modify ->fixups
before. This is correct but fragile, change it to use "|=".

Also make ->fixups u8, we are going to add the new members into the
union. It is not clear why UPROBE_FIX_RIP_.X lived in the upper byte,
redefine them so that they can fit into u8.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
parent 97aa5cdd

arch/x86/include/asm/uprobes.h

+1 −1
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ struct arch_uprobe { 
#ifdef CONFIG_X86_64

			long	riprel_target;

#endif

			u16	fixups;

			u8	fixups;

		} 			def;

	};

};

arch/x86/kernel/uprobes.c

+7 −7
Original line number Diff line number Diff line
@@ -33,16 +33,16 @@ 
/* Post-execution fixups. */



/* Adjust IP back to vicinity of actual insn */

#define UPROBE_FIX_IP		0x1

#define UPROBE_FIX_IP		0x01



/* Adjust the return address of a call insn */

#define UPROBE_FIX_CALL	0x2

#define UPROBE_FIX_CALL		0x02



/* Instruction will modify TF, don't change it */

#define UPROBE_FIX_SETF	0x4

#define UPROBE_FIX_SETF		0x04



#define UPROBE_FIX_RIP_AX	0x8000

#define UPROBE_FIX_RIP_CX	0x4000

#define UPROBE_FIX_RIP_AX	0x08

#define UPROBE_FIX_RIP_CX	0x10



#define	UPROBE_TRAP_NR		UINT_MAX
@@ -307,12 +307,12 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn) 
		 * is NOT the register operand, so we use %rcx (register

		 * #1) for the scratch register.

		 */

		auprobe->def.fixups = UPROBE_FIX_RIP_CX;

		auprobe->def.fixups |= UPROBE_FIX_RIP_CX;

		/* Change modrm from 00 000 101 to 00 000 001. */

		*cursor = 0x1;

	} else {

		/* Use %rax (register #0) for the scratch register. */

		auprobe->def.fixups = UPROBE_FIX_RIP_AX;

		auprobe->def.fixups |= UPROBE_FIX_RIP_AX;

		/* Change modrm from 00 xxx 101 to 00 xxx 000 */

		*cursor = (reg << 3);

	}