diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/arm64/kernel/syscall.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index c938603b3ba0..d72e8f23422d 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -67,7 +67,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, * * The resulting 5 bits of entropy is seen in SP[8:4]. */ - choose_random_kstack_offset(get_random_int() & 0x1FF); + choose_random_kstack_offset(get_random_u16() & 0x1FF); } static inline bool has_syscall_work(unsigned long flags) @@ -158,11 +158,36 @@ trace_exit: syscall_trace_exit(regs); } -static inline void sve_user_discard(void) +/* + * As per the ABI exit SME streaming mode and clear the SVE state not + * shared with FPSIMD on syscall entry. + */ +static inline void fp_user_discard(void) { + /* + * If SME is active then exit streaming mode. If ZA is active + * then flush the SVE registers but leave userspace access to + * both SVE and SME enabled, otherwise disable SME for the + * task and fall through to disabling SVE too. This means + * that after a syscall we never have any streaming mode + * register state to track, if this changes the KVM code will + * need updating. + */ + if (system_supports_sme() && test_thread_flag(TIF_SME)) { + u64 svcr = read_sysreg_s(SYS_SVCR); + + if (svcr & SVCR_SM_MASK) + sme_smstop_sm(); + } + if (!system_supports_sve()) return; + /* + * If SME is not active then disable SVE, the registers will + * be cleared when userspace next attempts to access them and + * we do not need to track the SVE register state until then. + */ clear_thread_flag(TIF_SVE); /* @@ -177,7 +202,7 @@ static inline void sve_user_discard(void) void do_el0_svc(struct pt_regs *regs) { - sve_user_discard(); + fp_user_discard(); el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table); } |