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-rw-r--r--arch/riscv/kernel/head.S11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 98a406474e7d..7ed1b22950fd 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -161,11 +161,20 @@ ENTRY(_start_kernel)
/* Reset all registers except ra, a0, a1 */
call reset_regs
- /* Setup a PMP to permit access to all of memory. */
+ /*
+ * Setup a PMP to permit access to all of memory. Some machines may
+ * not implement PMPs, so we set up a quick trap handler to just skip
+ * touching the PMPs on any trap.
+ */
+ la a0, pmp_done
+ csrw CSR_TVEC, a0
+
li a0, -1
csrw CSR_PMPADDR0, a0
li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X)
csrw CSR_PMPCFG0, a0
+.align 2
+pmp_done:
/*
* The hartid in a0 is expected later on, and we have no firmware