lkml.org 
[lkml]   [2014]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2 6/9] 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).

TODO: An error from adjust_ret_addr() shouldn't be silently ignored,
we should teach arch_uprobe_post_xol() or handle_singlestep() paths
to restart the probed insn in this case. And probably "adjust" can
be simplified and turned into set_ret_addr(). It seems that we do
not really need copy_from_user(), we can always calculate the value
we need to write into *regs->sp.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
---
arch/x86/include/asm/uprobes.h | 7 ++-
arch/x86/kernel/uprobes.c | 107 +++++++++++++++++++++++++--------------
2 files changed, 74 insertions(+), 40 deletions(-)

diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 3087ea9..9f8210b 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -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
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 3bb4198..13ad8a3 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -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;
--
1.5.5.1


\
 
 \ /
  Last update: 2014-04-04 23:41    [W:0.265 / U:0.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site