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uprobes/x86: Introduce uprobe_xol_ops and arch_uprobe->ops 

Introduce arch_uprobe->ops pointing to the "struct uprobe_xol_ops",
move the current UPROBE_FIX_{RIP*,IP,CALL} code into the default
set of methods and change arch_uprobe_pre/post_xol() accordingly.

This way we can add the new uprobe_xol_ops's to handle the insns
which need the special processing (rip-relative jmp/call at least).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
This commit is contained in:
Oleg Nesterov 2014-03-31 21:01:31 +02:00
parent 34e7317d6a
commit 8ad8e9d3fd
2 changed files with 74 additions and 40 deletions
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7
arch/x86/include/asm/uprobes.h
View File

@ -33,12 +33,17 @@ typedef u8 uprobe_opcode_t;
#define UPROBE_SWBP_INSN 0xcc
#define UPROBE_SWBP_INSN_SIZE 1
struct uprobe_xol_ops;
struct arch_uprobe {
u16 fixups;
union {
u8 insn[MAX_UINSN_BYTES];
u8 ixol[MAX_UINSN_BYTES];
};
u16 fixups;
const struct uprobe_xol_ops *ops;
#ifdef CONFIG_X86_64
unsigned long rip_rela_target_address;
#endif

107
arch/x86/kernel/uprobes.c
View File

@ -402,6 +402,64 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
}
#endif /* CONFIG_X86_64 */
struct uprobe_xol_ops {
bool (*emulate)(struct arch_uprobe *, struct pt_regs *);
int (*pre_xol)(struct arch_uprobe *, struct pt_regs *);
int (*post_xol)(struct arch_uprobe *, struct pt_regs *);
};
static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
pre_xol_rip_insn(auprobe, regs, &current->utask->autask);
return 0;
}
/*
* Adjust the return address pushed by a call insn executed out of line.
*/
static int adjust_ret_addr(unsigned long sp, long correction)
{
int rasize, ncopied;
long ra = 0;
if (is_ia32_task())
rasize = 4;
else
rasize = 8;
ncopied = copy_from_user(&ra, (void __user *)sp, rasize);
if (unlikely(ncopied))
return -EFAULT;
ra += correction;
ncopied = copy_to_user((void __user *)sp, &ra, rasize);
if (unlikely(ncopied))
return -EFAULT;
return 0;
}
static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
long correction = (long)(utask->vaddr - utask->xol_vaddr);
int ret = 0;
handle_riprel_post_xol(auprobe, regs, &correction);
if (auprobe->fixups & UPROBE_FIX_IP)
regs->ip += correction;
if (auprobe->fixups & UPROBE_FIX_CALL)
ret = adjust_ret_addr(regs->sp, correction);
return ret;
}
static struct uprobe_xol_ops default_xol_ops = {
.pre_xol = default_pre_xol_op,
.post_xol = default_post_xol_op,
};
/**
* arch_uprobe_analyze_insn - instruction analysis including validity and fixups.
* @mm: the probed address space.
@ -464,6 +522,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
if (fix_call)
auprobe->fixups |= UPROBE_FIX_CALL;
auprobe->ops = &default_xol_ops;
return 0;
}
@ -485,33 +544,8 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))
set_task_blockstep(current, false);
pre_xol_rip_insn(auprobe, regs, &utask->autask);
return 0;
}
/*
* This function is called by arch_uprobe_post_xol() to adjust the return
* address pushed by a call instruction executed out of line.
*/
static int adjust_ret_addr(unsigned long sp, long correction)
{
int rasize, ncopied;
long ra = 0;
if (is_ia32_task())
rasize = 4;
else
rasize = 8;
ncopied = copy_from_user(&ra, (void __user *)sp, rasize);
if (unlikely(ncopied))
return -EFAULT;
ra += correction;
ncopied = copy_to_user((void __user *)sp, &ra, rasize);
if (unlikely(ncopied))
return -EFAULT;
if (auprobe->ops->pre_xol)
return auprobe->ops->pre_xol(auprobe, regs);
return 0;
}
@ -560,11 +594,8 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t)
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
long correction;
int result = 0;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
@ -576,15 +607,9 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
regs->flags &= ~X86_EFLAGS_TF;
correction = (long)(utask->vaddr - utask->xol_vaddr);
handle_riprel_post_xol(auprobe, regs, &correction);
if (auprobe->fixups & UPROBE_FIX_IP)
regs->ip += correction;
if (auprobe->fixups & UPROBE_FIX_CALL)
result = adjust_ret_addr(regs->sp, correction);
return result;
if (auprobe->ops->post_xol)
return auprobe->ops->post_xol(auprobe, regs);
return 0;
}
/* callback routine for handling exceptions. */
@ -642,6 +667,10 @@ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
int i;
if (auprobe->ops->emulate)
return auprobe->ops->emulate(auprobe, regs);
/* TODO: move this code into ->emulate() hook */
for (i = 0; i < MAX_UINSN_BYTES; i++) {
if (auprobe->insn[i] == 0x66)
continue;