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riscv: Return to previous privilege level after trap handling

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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>
This commit is contained in:
Bin Meng 2018-12-12 06:12:43 -08:00 committed by Andes
parent 496262cca6
commit 10753ef8fd
1 changed files with 0 additions and 8 deletions
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8
arch/riscv/cpu/mtrap.S
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@ -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)