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Subject[PATCH 1/4] RISC-V: Setup exception vector early
Date
The trap vector is set only in trap_init which may be too late in some
cases. Early ioremap/efi spits many warning messages which may be useful.

Setup the trap vector early so that any warning/bug can be handled before
generic code invokes trap_init.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
arch/riscv/kernel/head.S | 10 ++++++++--
arch/riscv/kernel/smpboot.c | 1 -
arch/riscv/kernel/traps.c | 8 +-------
3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 7ed1b22950fd..d0c5c316e9bb 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -77,10 +77,16 @@ relocate:
csrw CSR_SATP, a0
.align 2
1:
- /* Set trap vector to spin forever to help debug */
- la a0, .Lsecondary_park
+ /* Set trap vector to exception handler */
+ la a0, handle_exception
csrw CSR_TVEC, a0

+ /*
+ * Set sup0 scratch register to 0, indicating to exception vector that
+ * we are presently executing in kernel.
+ */
+ csrw CSR_SCRATCH, zero
+
/* Reload the global pointer */
.option push
.option norelax
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 4e9922790f6e..5a9c127a380e 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -154,7 +154,6 @@ asmlinkage __visible void smp_callin(void)
mmgrab(mm);
current->active_mm = mm;

- trap_init();
notify_cpu_starting(smp_processor_id());
update_siblings_masks(smp_processor_id());
set_cpu_online(smp_processor_id(), 1);
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 7d95cce5e47c..ad14f4466d92 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -174,13 +174,7 @@ int is_valid_bugaddr(unsigned long pc)
}
#endif /* CONFIG_GENERIC_BUG */

+/* stvec & scratch is already set from head.S */
void trap_init(void)
{
- /*
- * Set sup0 scratch register to 0, indicating to exception vector
- * that we are presently executing in the kernel
- */
- csr_write(CSR_SCRATCH, 0);
- /* Set the exception vector address */
- csr_write(CSR_TVEC, &handle_exception);
}
--
2.24.0
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