diff options
Diffstat (limited to 'arch/arm64/kernel/syscall.c')
| -rw-r--r-- | arch/arm64/kernel/syscall.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index ad198262b981..7230f6e20ab8 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -53,17 +53,15 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, syscall_set_return_value(current, regs, 0, ret); /* - * Ultimately, this value will get limited by KSTACK_OFFSET_MAX(), - * but not enough for arm64 stack utilization comfort. To keep - * reasonable stack head room, reduce the maximum offset to 9 bits. + * This value will get limited by KSTACK_OFFSET_MAX(), which is 10 + * bits. The actual entropy will be further reduced by the compiler + * when applying stack alignment constraints: the AAPCS mandates a + * 16-byte aligned SP at function boundaries, which will remove the + * 4 low bits from any entropy chosen here. * - * The actual entropy will be further reduced by the compiler when - * applying stack alignment constraints: the AAPCS mandates a - * 16-byte (i.e. 4-bit) aligned SP at function boundaries. - * - * The resulting 5 bits of entropy is seen in SP[8:4]. + * The resulting 6 bits of entropy is seen in SP[9:4]. */ - choose_random_kstack_offset(get_random_u16() & 0x1FF); + choose_random_kstack_offset(get_random_u16()); } static inline bool has_syscall_work(unsigned long flags) |