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Revert "ia64: kprobes: Use generic kretprobe trampoline handler"

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This reverts commit 77fa5e15c9.

Since the upstream commit e792ff804f49720ce003b3e4c618b5d996256a18
depends on the generic kretprobe trampoline handler, which was
introduced by commit 66ada2ccae4e ("kprobes: Add generic kretprobe
trampoline handler") but that is not ported to the stable kernel
because it is not a bugfix series.
So revert this commit to fix a build error.

NOTE: I keep commit a7fe2378454c ("ia64: kprobes: Fix to pass
correct trampoline address to the handler") on the tree, that seems
just a cleanup without the original reverted commit, but it would
be better to use dereference_function_descriptor() macro instead
of accessing descriptor's field directly.

Fixes: 77fa5e15c9 ("ia64: kprobes: Use generic kretprobe trampoline handler")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Masami Hiramatsu 2022-01-15 21:59:16 +09:00 committed by Greg Kroah-Hartman
parent d106693dfd
commit 2c9650faa1
1 changed files with 75 additions and 3 deletions
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78
arch/ia64/kernel/kprobes.c
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@ -396,10 +396,83 @@ static void kretprobe_trampoline(void)
{
}
/*
* At this point the target function has been tricked into
* returning into our trampoline. Lookup the associated instance
* and then:
* - call the handler function
* - cleanup by marking the instance as unused
* - long jump back to the original return address
*/
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
regs->cr_iip = __kretprobe_trampoline_handler(regs,
dereference_function_descriptor(kretprobe_trampoline), NULL);
struct kretprobe_instance *ri = NULL;
struct hlist_head *head, empty_rp;
struct hlist_node *tmp;
unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address =
(unsigned long)dereference_function_descriptor(kretprobe_trampoline);
INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags);
/*
* It is possible to have multiple instances associated with a given
* task either because an multiple functions in the call path
* have a return probe installed on them, and/or more than one return
* return probe was registered for a target function.
*
* We can handle this because:
* - instances are always inserted at the head of the list
* - when multiple return probes are registered for the same
* function, the first instance's ret_addr will point to the
* real return address, and all the rest will point to
* kretprobe_trampoline
*/
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
orig_ret_address = (unsigned long)ri->ret_addr;
if (orig_ret_address != trampoline_address)
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
}
regs->cr_iip = orig_ret_address;
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
if (ri->rp && ri->rp->handler)
ri->rp->handler(ri, regs);
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri, &empty_rp);
if (orig_ret_address != trampoline_address)
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
}
kretprobe_assert(ri, orig_ret_address, trampoline_address);
kretprobe_hash_unlock(current, &flags);
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we don't want the post_handler
@ -412,7 +485,6 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->b0;
ri->fp = NULL;
/* Replace the return addr with trampoline addr */
regs->b0 = (unsigned long)dereference_function_descriptor(kretprobe_trampoline);