entry: kmsan: introduce kmsan_unpoison_entry_regs()

struct pt_regs passed into IRQ entry code is set up by uninstrumented asm
functions, therefore KMSAN may not notice the registers are initialized.

kmsan_unpoison_entry_regs() unpoisons the contents of struct pt_regs,
preventing potential false positives.  Unlike kmsan_unpoison_memory(), it
can be called under kmsan_in_runtime(), which is often the case in IRQ
entry code.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Potapenko <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Ilya Leoshkevich <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
index c473e0e21683..e38ae3c34618 100644
--- a/include/linux/kmsan.h
+++ b/include/linux/kmsan.h
@@ -214,6 +214,17 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
  */
 void kmsan_handle_urb(const struct urb *urb, bool is_out);
 
+/**
+ * kmsan_unpoison_entry_regs() - Handle pt_regs in low-level entry code.
+ * @regs:	struct pt_regs pointer received from assembly code.
+ *
+ * KMSAN unpoisons the contents of the passed pt_regs, preventing potential
+ * false positive reports. Unlike kmsan_unpoison_memory(),
+ * kmsan_unpoison_entry_regs() can be called from the regions where
+ * kmsan_in_runtime() returns true, which is the case in early entry code.
+ */
+void kmsan_unpoison_entry_regs(const struct pt_regs *regs);
+
 #else
 
 static inline void kmsan_init_shadow(void)
@@ -310,6 +321,10 @@ static inline void kmsan_handle_urb(const struct urb *urb, bool is_out)
 {
 }
 
+static inline void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
+{
+}
+
 #endif
 
 #endif /* _LINUX_KMSAN_H */