[PATCH 1/2] xtensa: add trap handler for division by zero

Max Filippov
2022-05-13T15:42:11Z

Add c-level handler for the division by zero exception and kill the task
if it was thrown from the kernel space or send SIGFPE otherwise.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
arch/xtensa/kernel/traps.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index d3e91ceb0775..7c7c4c7b33bb 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -49,6 +49,7 @@
*/

static void do_illegal_instruction(struct pt_regs *regs);
+static void do_div0(struct pt_regs *regs);
static void do_interrupt(struct pt_regs *regs);
#if XTENSA_FAKE_NMI
static void do_nmi(struct pt_regs *regs);
@@ -95,7 +96,7 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
#ifdef SUPPORT_WINDOWED
{ EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
#endif
-/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
+{ EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 },
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
@@ -307,6 +308,11 @@ static void do_illegal_instruction(struct pt_regs *regs)
force_sig(SIGILL);
}

+static void do_div0(struct pt_regs *regs)
+{
+ __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
+ force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
+}

/*
* Handle unaligned memory accesses from user space. Kill task.
--
2.30.2