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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@redhat.com>
This commit is contained in:
Oleg Nesterov 2014-04-25 18:06:19 +02:00
parent 2b82cadffc
commit 1dc76e6eac
2 changed files with 4 additions and 21 deletions
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1
arch/x86/include/asm/uprobes.h
View File

@ -54,6 +54,7 @@ struct arch_uprobe {
long riprel_target;
#endif
u8 fixups;
u8 ilen;
} def;
};
};

24
arch/x86/kernel/uprobes.c
View File

@ -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)