[PATCH 11/32] riscv: Enable interrupts during syscalls with M-Mode

Damien Le Moal
2020-11-07T08:15:10Z

When running is M-Mode (no MMU config), MPIE does not get set. This
results in all syscalls being executed with interrupts disabled as
handle_exception never sets SR_IE as it always sees SR_PIE being
cleared. Fix this by always force enabling interrupts in
handle_syscall when CONFIG_RISCV_M_MODE is enabled.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
---
arch/riscv/kernel/entry.S | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 524d918f3601..080eb8d78589 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -155,6 +155,15 @@ skip_context_tracking:
tail do_trap_unknown

handle_syscall:
+#ifdef CONFIG_RISCV_M_MODE
+ /*
+ * When running is M-Mode (no MMU config), MPIE does not get set.
+ * As a result, we need to force enable interrupts here because
+ * handle_exception did not do set SR_IE as it always sees SR_PIE
+ * being cleared.
+ */
+ csrs CSR_STATUS, SR_IE
+#endif
#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
/* Recover a0 - a7 for system calls */
REG_L a0, PT_A0(sp)
--
2.28.0