diff options
| -rw-r--r-- | firmware/fw_base.S | 32 | ||||
| -rw-r--r-- | lib/sbi/sbi_init.c | 31 |
2 files changed, 31 insertions, 32 deletions
diff --git a/firmware/fw_base.S b/firmware/fw_base.S index 043de7d7..5d6540d7 100644 --- a/firmware/fw_base.S +++ b/firmware/fw_base.S @@ -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 diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index aae035e1..b248e73f 100644 --- a/lib/sbi/sbi_init.c +++ b/lib/sbi/sbi_init.c @@ -218,6 +218,8 @@ static void wake_coldboot_harts(struct sbi_scratch *scratch) __smp_store_release(&coldboot_done, 1); } +unsigned long __stack_chk_guard = 0x95B5FF5A; + static unsigned long entry_count_offset; static unsigned long init_count_offset; @@ -269,6 +271,35 @@ static void __noreturn init_coldboot(struct sbi_scratch *scratch, u32 hartid) if (rc) sbi_hart_hang(); + /* + * Initialize stack guard via Zkr entropy source if Zkr is + * implemented according to device tree. Writing new seed value + * to __stack_chk_guard is safe here because function doesn't + * return and no check against value on entry will be done. + */ + if (sbi_hart_has_extension(scratch, SBI_HART_EXT_ZKR)) { + unsigned long guard_val = 0; + int chunks = sizeof(unsigned long) / sizeof(uint16_t); + bool res = true; + + while (chunks) { + unsigned long seed = csr_swap(CSR_SEED, 0); + unsigned long opst = seed & SEED_OPTS_MASK; + + if (opst == SEED_OPTS_DEAD) { + res = false; + break; + } + if (opst == SEED_OPTS_ES16) { + guard_val = (guard_val << 16) | (seed & SEED_ENTROPY_MASK); + chunks--; + } + continue; + } + if (res) + __stack_chk_guard = guard_val; + } + rc = sbi_timer_init(scratch, true); if (rc) sbi_hart_hang(); |