/*
* Called after single-stepping. To avoid the SMP problems that can
* occur when we temporarily put back the original opcode to
* single-step, we single-stepped a copy of the instruction.
*
* This function prepares to resume execution after the single-step.
* We have to fix things up as follows:
*
* Typically, the new ip is relative to the copied instruction. We need
* to make it relative to the original instruction (FIX_IP). Exceptions
* are return instructions and absolute or indirect jump or call instructions.
*
* If the single-stepped instruction was a call, the return address that
* is atop the stack is the address following the copied instruction. We
* need to make it the address following the original instruction (FIX_CALL).
*
* If the original instruction was a rip-relative instruction such as
* "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
* instruction using a scratch register -- e.g., "movl %edx,(%rax)".
* We need to restore the contents of the scratch register and adjust
* the ip, keeping in mind that the instruction we executed is 4 bytes
* shorter than the original instruction (since we squeezed out the offset
* field). (FIX_RIP_AX or FIX_RIP_CX)
*/
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask;
long correction;
int result = 0;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
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);
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
* so we can get an extra SIGTRAP if we do not clear TF. We need
* to examine the opcode to make it right.
*/
if (utask->autask.saved_tf)
send_sig(SIGTRAP, current, 0);
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
regs->flags &= ~X86_EFLAGS_TF;
return result;
}
/*
* Called after single-stepping. ppt->vaddr is the address of the
* instruction whose first byte has been replaced by the "int3"
* instruction. To avoid the SMP problems that can occur when we
* temporarily put back the original opcode to single-step, we
* single-stepped a copy of the instruction. The address of this
* copy is utask->singlestep_addr.
*
* This function prepares to return from the post-single-step
* interrupt. We have to fix up the stack as follows:
*
* 0) Typically, the new eip is relative to the copied instruction. We
* need to make it relative to the original instruction. Exceptions are
* return instructions and absolute or indirect jump or call instructions.
*
* 1) If the single-stepped instruction was a call, the return address
* that is atop the stack is the address following the copied instruction.
* We need to make it the address following the original instruction.
*/
static
void uprobe_post_ssout(struct uprobe_task *utask, struct uprobe_probept *ppt,
struct pt_regs *regs)
{
long copy_eip = utask->singlestep_addr;
long orig_eip = ppt->vaddr;
unsigned long flags = ppt->arch_info.flags;
up_read(&ppt->slot->rwsem);
if (flags & UPFIX_RETURN)
adjust_ret_addr(regs->esp, (orig_eip - copy_eip), utask);
if (!(flags & UPFIX_ABS_IP))
regs->eip = orig_eip + (regs->eip - copy_eip);
}
/*
* Called after single-stepping. To avoid the SMP problems that can
* occur when we temporarily put back the original opcode to
* single-step, we single-stepped a copy of the instruction.
*
* This function prepares to resume execution after the single-step.
* We have to fix things up as follows:
*
* Typically, the new ip is relative to the copied instruction. We need
* to make it relative to the original instruction (FIX_IP). Exceptions
* are return instructions and absolute or indirect jump or call instructions.
*
* If the single-stepped instruction was a call, the return address that
* is atop the stack is the address following the copied instruction. We
* need to make it the address following the original instruction (FIX_CALL).
*
* If the original instruction was a rip-relative instruction such as
* "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
* instruction using a scratch register -- e.g., "movl %edx,(%rax)".
* We need to restore the contents of the scratch register and adjust
* the ip, keeping in mind that the instruction we executed is 4 bytes
* shorter than the original instruction (since we squeezed out the offset
* field). (FIX_RIP_AX or FIX_RIP_CX)
*/
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask;
long correction;
int result = 0;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
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;
}
