[tip: perf/core] x86,kprobes: WARN if kprobes tries to handle a fault

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     00afe83098f59d3091a800d0db188ca495b2bc02
Gitweb:        https://git.kernel.org/tip/00afe83098f59d3091a800d0db188ca495b2bc02
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Tue, 25 May 2021 09:25:20 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 01 Jun 2021 16:00:09 +02:00

x86,kprobes: WARN if kprobes tries to handle a fault

With the removal of kprobe::handle_fault there is no reason left that
kprobe_page_fault() would ever return true on x86, make sure it
doesn't happen by accident.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210525073213.660594073@xxxxxxxxxxxxx
---
 arch/x86/mm/fault.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 1c548ad..362255b 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1186,7 +1186,7 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
 		return;
 
 	/* kprobes don't want to hook the spurious faults: */
-	if (kprobe_page_fault(regs, X86_TRAP_PF))
+	if (WARN_ON_ONCE(kprobe_page_fault(regs, X86_TRAP_PF)))
 		return;
 
 	/*
@@ -1239,7 +1239,7 @@ void do_user_addr_fault(struct pt_regs *regs,
 	}
 
 	/* kprobes don't want to hook the spurious faults: */
-	if (unlikely(kprobe_page_fault(regs, X86_TRAP_PF)))
+	if (WARN_ON_ONCE(kprobe_page_fault(regs, X86_TRAP_PF)))
 		return;
 
 	/*