Commit-ID: 1dc76e6eacef271230d9ff6fd0f91824bda03f44
Gitweb: http://git.kernel.org/tip/1dc76e6eacef271230d9ff6fd0f91824bda03f44
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Fri, 25 Apr 2014 18:06:19 +0200
Committer: Oleg Nesterov <oleg@xxxxxxxxxx>
CommitDate: Wed, 30 Apr 2014 19:10:39 +0200
uprobes/x86: Kill adjust_ret_addr(), simplify UPROBE_FIX_CALL logic
The only insn which could have both UPROBE_FIX_IP and UPROBE_FIX_CALL
was 0xe8 "call relative", and now it is handled by branch_xol_ops.
So we can change default_post_xol_op(UPROBE_FIX_CALL) to simply push
the address of next insn == utask->vaddr + insn.length, just we need
to record insn.length into the new auprobe->def.ilen member.
Note: if/when we teach branch_xol_ops to support jcxz/loopz we can
remove the "correction" logic, UPROBE_FIX_IP can use the same address.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
arch/x86/include/asm/uprobes.h | 1 +
arch/x86/kernel/uprobes.c | 24 +++---------------------
2 files changed, 4 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 9ce25ce..a040d49 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -54,6 +54,7 @@ struct arch_uprobe {
long riprel_target;
#endif
u8 fixups;
+ u8 ilen;
} def;
};
};
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index df75913..5bcce85 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -418,24 +418,6 @@ static int push_ret_address(struct pt_regs *regs, unsigned long ip)
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 = sizeof_long();
- long ra;
-
- if (copy_from_user(&ra, (void __user *)sp, rasize))
- return -EFAULT;
-
- ra += correction;
- if (copy_to_user((void __user *)sp, &ra, rasize))
- return -EFAULT;
-
- return 0;
-}
-
static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
@@ -446,10 +428,9 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
regs->ip += correction;
if (auprobe->def.fixups & UPROBE_FIX_CALL) {
- if (adjust_ret_addr(regs->sp, correction)) {
- regs->sp += sizeof_long();
+ regs->sp += sizeof_long();
+ if (push_ret_address(regs, utask->vaddr + auprobe->def.ilen))
return -ERESTART;
- }
}
/* popf; tell the caller to not touch TF */
if (auprobe->def.fixups & UPROBE_FIX_SETF)
@@ -687,6 +668,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
handle_riprel_insn(auprobe, &insn);
}
+ auprobe->def.ilen = insn.length;
if (fix_ip)
auprobe->def.fixups |= UPROBE_FIX_IP;
if (fix_call)
--
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