Mirrors/opensbi
3
0
Fork 1
mirror of https://github.com/riscv-software-src/opensbi.git synced 2026-05-23 14:21:32 +01:00
Code Issues Packages Projects Releases Wiki Activity

lib: sbi: Move Zkr entropy initialization from fw_base.S to init_coldboot

Browse Source 
Current placement of entropy initialization via Zkr extension requires a
trap-based mechanism to handle absent Zkr extension case. In presence of
Smrnmi extension no trap-based mechanisms should be used before Smrnmi is
detected and enabled otherwise trap will jump to undefined location.
Move stack guard initialization into init_coldboot function body after
device tree has been parsed so we know if Zkr extension is implemented by
the platform which helps to avoid trap-based discovery.
init_coldboot() is a safe place to initialize entropy because it doesn't
return so no check of __stack_chk_guard against value on entry
will be done.

Signed-off-by: Evgeny Voevodin <evvoevod@tenstorrent.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/acd52b0f3468758bc5f09e6a45662341b31d4d87.1778176768.git.evvoevod@tenstorrent.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Evgeny Voevodin
2026-05-07 18:08:06 +00:00
committed by Anup Patel
parent 882b8b081c
commit 0cfd6c0b5e
2 changed files with 31 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files
firmware/fw_base.S
-32
View File
@@ -107,30 +107,6 @@ _bss_zero:
add s4, s4, __SIZEOF_POINTER__
blt s4, s5, _bss_zero
/* Trying to initialize the stack guard via the Zkr extension */
lla t0, __stack_chk_guard_done
csrw CSR_MTVEC, t0
li t0, 0
li t3, SEED_OPTS_ES16
li t4, SEED_ENTROPY_MASK
li t5, __SIZEOF_POINTER__
__stack_chk_guard_loop:
csrrw t1, CSR_SEED, x0
li t2, SEED_OPTS_MASK
and t2, t2, t1
bgtu t2, t3, __stack_chk_guard_done
bltu t2, t3, __stack_chk_guard_loop
and t1, t1, t4
slli t0, t0, 16
or t0, t0, t1
addi t5, t5, -2
bgtz t5, __stack_chk_guard_loop
lla t1, __stack_chk_guard
REG_S t0, 0(t1)
j __stack_chk_guard_done
.align 3
__stack_chk_guard_done:
/* Setup temporary trap handler */
lla s4, _start_hang
csrw CSR_MTVEC, s4
@@ -895,14 +871,6 @@ __stack_chk_fail:
la a0, .Lstack_corrupt_msg
call sbi_panic
/* Initial value of the stack guard variable */
.section .data
.align 3
.globl __stack_chk_guard
.type __stack_chk_guard, %object
__stack_chk_guard:
RISCV_PTR 0x95B5FF5A
#ifdef FW_FDT_PATH
.section .rodata
.align 4