rseq: Replace the original debug implementation

Just utilize the new infrastructure and put the original one to rest.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084307.212510692@linutronix.de

diff --git a/kernel/rseq.c b/kernel/rseq.c
index 12a9b6ab2cefd7ccb4bf7edb3349b130427648cc..abd6bfadbcc66746f10dc5a6d66301fd30054b9b 100644 (file)
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -474,85 +474,28 @@ error:
 }
 
 #ifdef CONFIG_DEBUG_RSEQ
-/*
- * Unsigned comparison will be true when ip >= start_ip, and when
- * ip < start_ip + post_commit_offset.
- */
-static bool in_rseq_cs(unsigned long ip, struct rseq_cs *rseq_cs)
-{
-       return ip - rseq_cs->start_ip < rseq_cs->post_commit_offset;
-}
-
-/*
- * If the rseq_cs field of 'struct rseq' contains a valid pointer to
- * user-space, copy 'struct rseq_cs' from user-space and validate its fields.
- */
-static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
-{
-       struct rseq __user *urseq = t->rseq.usrptr;
-       struct rseq_cs __user *urseq_cs;
-       u32 __user *usig;
-       u64 ptr;
-       u32 sig;
-       int ret;
-
-       if (get_user(ptr, &rseq->rseq_cs))
-               return -EFAULT;
-
-       /* If the rseq_cs pointer is NULL, return a cleared struct rseq_cs. */
-       if (!ptr) {
-               memset(rseq_cs, 0, sizeof(*rseq_cs));
-               return 0;
-       }
-       /* Check that the pointer value fits in the user-space process space. */
-       if (ptr >= TASK_SIZE)
-               return -EINVAL;
-       urseq_cs = (struct rseq_cs __user *)(unsigned long)ptr;
-       if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)))
-               return -EFAULT;
-
-       if (rseq_cs->start_ip >= TASK_SIZE ||
-           rseq_cs->start_ip + rseq_cs->post_commit_offset >= TASK_SIZE ||
-           rseq_cs->abort_ip >= TASK_SIZE ||
-           rseq_cs->version > 0)
-               return -EINVAL;
-       /* Check for overflow. */
-       if (rseq_cs->start_ip + rseq_cs->post_commit_offset < rseq_cs->start_ip)
-               return -EINVAL;
-       /* Ensure that abort_ip is not in the critical section. */
-       if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset)
-               return -EINVAL;
-
-       usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32));
-       ret = get_user(sig, usig);
-       if (ret)
-               return ret;
-
-       if (current->rseq.sig != sig) {
-               printk_ratelimited(KERN_WARNING
-                       "Possible attack attempt. Unexpected rseq signature 0x%x, expecting 0x%x (pid=%d, addr=%p).\n",
-                       sig, current->rseq.sig, current->pid, usig);
-               return -EINVAL;
-       }
-       return 0;
-}
-
 /*
  * Terminate the process if a syscall is issued within a restartable
  * sequence.
  */
 void rseq_syscall(struct pt_regs *regs)
 {
-       unsigned long ip = instruction_pointer(regs);
        struct task_struct *t = current;
-       struct rseq_cs rseq_cs;
+       u64 csaddr;
 
-       if (!t->rseq.usrptr)
+       if (!t->rseq.event.has_rseq)
                return;
-       if (rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))
-               force_sig(SIGSEGV);
+       if (get_user(csaddr, &t->rseq.usrptr->rseq_cs))
+               goto fail;
+       if (likely(!csaddr))
+               return;
+       if (unlikely(csaddr >= TASK_SIZE))
+               goto fail;
+       if (rseq_debug_update_user_cs(t, regs, csaddr))
+               return;
+fail:
+       force_sig(SIGSEGV);
 }
-
 #endif
 
 /*