[PATCH V6 05/11] riscv: traps: Add noinstr to prevent instrumentation inserted

From: guoren
Date: Sat Oct 01 2022 - 21:26:34 EST

From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

Without noinstr the compiler is free to insert instrumentation (think
all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
yet ready to run this early in the entry path, for instance it could
rely on RCU which isn't on yet, or expect lockdep state. (by peterz)

Link: https://lore.kernel.org/linux-riscv/YxcQ6NoPf3AH0EXe@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/raw
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
arch/riscv/kernel/traps.c | 4 ++--
arch/riscv/mm/fault.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 635e6ec26938..588e17c386c6 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -92,9 +92,9 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,

-#define __trap_section __section(".xip.traps")
+#define __trap_section __noinstr_section(".xip.traps")
-#define __trap_section
+#define __trap_section noinstr
#define DO_ERROR_INFO(name, signo, code, str) \
asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index f2fbd1400b7c..c7829289e806 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -203,7 +203,7 @@ static inline bool access_error(unsigned long cause, struct vm_area_struct *vma)
* This routine handles page faults. It determines the address and the
* problem, and then passes it off to one of the appropriate routines.
-asmlinkage void do_page_fault(struct pt_regs *regs)
+asmlinkage void noinstr do_page_fault(struct pt_regs *regs)
struct task_struct *tsk;
struct vm_area_struct *vma;