From: Bin Meng <bmeng.cn@gmail.com>
Date: Wed, 12 Dec 2018 14:12:43 +0000 (-0800)
Subject: riscv: Return to previous privilege level after trap handling
X-Git-Url: http://git.dujemihanovic.xyz/html/index.html?a=commitdiff_plain;h=10753ef8fd14dfe1d41ec253966569de19463adc;p=u-boot.git

riscv: Return to previous privilege level after trap handling

At present the trap handler returns to hardcoded M-mode/S-mode.
Change to returning to previous privilege level instead.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
---

diff --git a/arch/riscv/cpu/mtrap.S b/arch/riscv/cpu/mtrap.S
index da307e4273..407ecfa9c0 100644
--- a/arch/riscv/cpu/mtrap.S
+++ b/arch/riscv/cpu/mtrap.S
@@ -68,14 +68,6 @@ trap_entry:
 	jal handle_trap
 	csrw MODE_PREFIX(epc), a0
 
-#ifdef CONFIG_RISCV_SMODE
-	/* Remain in S-mode after sret */
-	li t0, SSTATUS_SPP
-#else
-	/* Remain in M-mode after mret */
-	li t0, MSTATUS_MPP
-#endif
-	csrs MODE_PREFIX(status), t0
 	LREG x1,   1 * REGBYTES(sp)
 	LREG x3,   3 * REGBYTES(sp)
 	LREG x4,   4 * REGBYTES(sp)