linux/arch/x86/include/asm/uprobes.h
Oleg Nesterov 7ba6db2d68 uprobes/x86: Emulate unconditional relative jmp's
Currently we always execute all insns out-of-line, including relative
jmp's and call's. This assumes that even if regs->ip points to nowhere
after the single-step, default_post_xol_op(UPROBE_FIX_IP) logic will
update it correctly.

However, this doesn't work if this regs->ip == xol_vaddr + insn_offset
is not canonical. In this case CPU generates #GP and general_protection()
kills the task which tries to execute this insn out-of-line.

Now that we have uprobe_xol_ops we can teach uprobes to emulate these
insns and solve the problem. This patch adds branch_xol_ops which has
a single branch_emulate_op() hook, so far it can only handle rel8/32
relative jmp's.

TODO: move ->fixup into the union along with rip_rela_target_address.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Jonathan Lebon <jlebon@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
2014-04-17 21:58:22 +02:00

67 lines
1.6 KiB
C

#ifndef _ASM_UPROBES_H
#define _ASM_UPROBES_H
/*
* User-space Probes (UProbes) for x86
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2008-2011
* Authors:
* Srikar Dronamraju
* Jim Keniston
*/
#include <linux/notifier.h>
typedef u8 uprobe_opcode_t;
#define MAX_UINSN_BYTES 16
#define UPROBE_XOL_SLOT_BYTES 128 /* to keep it cache aligned */
#define UPROBE_SWBP_INSN 0xcc
#define UPROBE_SWBP_INSN_SIZE 1
struct uprobe_xol_ops;
struct arch_uprobe {
union {
u8 insn[MAX_UINSN_BYTES];
u8 ixol[MAX_UINSN_BYTES];
};
u16 fixups;
const struct uprobe_xol_ops *ops;
union {
#ifdef CONFIG_X86_64
unsigned long rip_rela_target_address;
#endif
struct {
s32 offs;
u8 ilen;
} branch;
};
};
struct arch_uprobe_task {
#ifdef CONFIG_X86_64
unsigned long saved_scratch_register;
#endif
unsigned int saved_trap_nr;
unsigned int saved_tf;
};
#endif /* _ASM_UPROBES_H */