1 /* Copyright 2019 SiFive, Inc */
2 /* SPDX-License-Identifier: Apache-2.0 */
6 #include <metal/privilege.h>
8 #define METAL_MSTATUS_MIE_OFFSET 3
9 #define METAL_MSTATUS_MPIE_OFFSET 7
10 #define METAL_MSTATUS_SIE_OFFSET 1
11 #define METAL_MSTATUS_SPIE_OFFSET 5
12 #define METAL_MSTATUS_UIE_OFFSET 0
13 #define METAL_MSTATUS_UPIE_OFFSET 4
15 #define METAL_MSTATUS_MPP_OFFSET 11
16 #define METAL_MSTATUS_MPP_MASK 3
18 void metal_privilege_drop_to_mode(enum metal_privilege_mode mode,
19 struct metal_register_file regfile,
20 metal_privilege_entry_point_t entry_point)
23 asm volatile("csrr %0, mstatus" : "=r" (mstatus));
25 /* Set xPIE bits based on current xIE bits */
26 if(mstatus && (1 << METAL_MSTATUS_MIE_OFFSET)) {
27 mstatus |= (1 << METAL_MSTATUS_MPIE_OFFSET);
29 mstatus &= ~(1 << METAL_MSTATUS_MPIE_OFFSET);
31 if(mstatus && (1 << METAL_MSTATUS_SIE_OFFSET)) {
32 mstatus |= (1 << METAL_MSTATUS_SPIE_OFFSET);
34 mstatus &= ~(1 << METAL_MSTATUS_SPIE_OFFSET);
36 if(mstatus && (1 << METAL_MSTATUS_UIE_OFFSET)) {
37 mstatus |= (1 << METAL_MSTATUS_UPIE_OFFSET);
39 mstatus &= ~(1 << METAL_MSTATUS_UPIE_OFFSET);
42 /* Set MPP to the requested privilege mode */
43 mstatus &= ~(METAL_MSTATUS_MPP_MASK << METAL_MSTATUS_MPP_OFFSET);
44 mstatus |= (mode << METAL_MSTATUS_MPP_OFFSET);
46 asm volatile("csrw mstatus, %0" :: "r" (mstatus));
48 /* Set the entry point in MEPC */
49 asm volatile("csrw mepc, %0" :: "r" (entry_point));
51 /* Set the register file */
52 asm volatile("mv ra, %0" :: "r" (regfile.ra));
53 asm volatile("mv sp, %0" :: "r" (regfile.sp));