@@ -517,4 +517,8 @@ void asm_offsets(void)
DEFINE(FREGS_A6, offsetof(struct ftrace_regs, a6));
DEFINE(FREGS_A7, offsetof(struct ftrace_regs, a7));
#endif
+ DEFINE(SBI_EXT_FWFT, SBI_EXT_FWFT);
+ DEFINE(SBI_EXT_FWFT_SET, SBI_EXT_FWFT_SET);
+ DEFINE(SBI_FWFT_SHADOW_STACK, SBI_FWFT_SHADOW_STACK);
+ DEFINE(SBI_FWFT_SET_FLAG_LOCK, SBI_FWFT_SET_FLAG_LOCK);
}
@@ -164,6 +164,12 @@ secondary_start_sbi:
call relocate_enable_mmu
#endif
call .Lsetup_trap_vector
+ li a7, SBI_EXT_FWFT
+ li a6, SBI_EXT_FWFT_SET
+ li a0, SBI_FWFT_SHADOW_STACK
+ li a1, 1 /* enable supervisor to access shadow stack access */
+ li a2, SBI_FWFT_SET_FLAG_LOCK
+ ecall
scs_load_current
call smp_callin
#endif /* CONFIG_SMP */
@@ -320,6 +326,12 @@ SYM_CODE_START(_start_kernel)
la tp, init_task
la sp, init_thread_union + THREAD_SIZE
addi sp, sp, -PT_SIZE_ON_STACK
+ li a7, SBI_EXT_FWFT
+ li a6, SBI_EXT_FWFT_SET
+ li a0, SBI_FWFT_SHADOW_STACK
+ li a1, 1 /* enable supervisor to access shadow stack access */
+ li a2, SBI_FWFT_SET_FLAG_LOCK
+ ecall
scs_load_current
#ifdef CONFIG_KASAN
Kernel will have to perform shadow stack operations on user shadow stack. Like during signal delivery and sigreturn, shadow stack token must be created and validated respectively. Thus shadow stack access for kernel must be enabled. In future when kernel shadow stacks are enabled for linux kernel, it must be enabled as early as possible for better coverage and prevent imbalance between regular stack and shadow stack. After `relocate_enable_mmu` has been done, this is as early as possible it can enabled. Signed-off-by: Deepak Gupta <debug@rivosinc.com> --- arch/riscv/kernel/asm-offsets.c | 4 ++++ arch/riscv/kernel/head.S | 12 ++++++++++++ 2 files changed, 16 insertions(+)