riscv: sifive: Apply errata "cip-453" patch

Add sign extension to the $badaddr before addressing the instruction page
fault and instruction access fault to workaround the issue "cip-453".

To avoid affecting the existing code sequence, this patch will creates two
trampolines to add sign extension to the $badaddr. By the "alternative"
mechanism, these two trampolines will replace the original exception
handler of instruction page fault and instruction access fault in the
excp_vect_table. In this case, only the specific SiFive CPU core jumps to
the do_page_fault and do_trap_insn_fault through these two trampolines.
Other CPUs are not affected.

Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/riscv/Kconfig.erratas b/arch/riscv/Kconfig.erratas
index 302e7467f302..b4146dca50fc 100644
--- a/arch/riscv/Kconfig.erratas
+++ b/arch/riscv/Kconfig.erratas
@@ -19,4 +19,15 @@ config ERRATA_SIFIVE
 
 	  Otherwise, please say "N" here to avoid unnecessary overhead.
 
+config ERRATA_SIFIVE_CIP_453
+	bool "Apply SiFive errata CIP-453"
+	depends on ERRATA_SIFIVE
+	default y
+	help
+	  This will apply the SiFive CIP-453 errata to add sign extension
+	  to the $badaddr when exception type is instruction page fault
+	  and instruction access fault.
+
+	  If you don't know what to do here, say "Y".
+
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