diff options
Diffstat (limited to 'arch/arm64/kernel/syscall.c')
| -rw-r--r-- | arch/arm64/kernel/syscall.c | 61 |
1 files changed, 12 insertions, 49 deletions
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index b1ae2f2eaf77..c062badd1a56 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -8,27 +8,24 @@ #include <linux/randomize_kstack.h> #include <linux/syscalls.h> -#include <asm/daifflags.h> #include <asm/debug-monitors.h> #include <asm/exception.h> #include <asm/fpsimd.h> #include <asm/syscall.h> #include <asm/thread_info.h> #include <asm/unistd.h> +#include <asm/unistd_compat_32.h> long compat_arm_syscall(struct pt_regs *regs, int scno); long sys_ni_syscall(void); static long do_ni_syscall(struct pt_regs *regs, int scno) { -#ifdef CONFIG_COMPAT - long ret; if (is_compat_task()) { - ret = compat_arm_syscall(regs, scno); + long ret = compat_arm_syscall(regs, scno); if (ret != -ENOSYS) return ret; } -#endif return sys_ni_syscall(); } @@ -46,7 +43,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, add_random_kstack_offset(); - if (scno < sc_nr) { + if (likely(scno < sc_nr)) { syscall_fn_t syscall_fn; syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)]; ret = __invoke_syscall(regs, syscall_fn); @@ -57,17 +54,15 @@ 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. - * - * 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. + * 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 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) @@ -101,9 +96,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, * (Similarly for HVC and SMC elsewhere.) */ - local_daif_restore(DAIF_PROCCTX); - - if (flags & _TIF_MTE_ASYNC_FAULT) { + if (unlikely(flags & _TIF_MTE_ASYNC_FAULT)) { /* * Process the asynchronous tag check fault before the actual * syscall. do_notify_resume() will send a signal to userspace @@ -153,45 +146,15 @@ trace_exit: syscall_trace_exit(regs); } -/* - * 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()) - sme_smstop_sm(); - - if (!system_supports_sve()) - return; - - if (test_thread_flag(TIF_SVE)) { - unsigned int sve_vq_minus_one; - - sve_vq_minus_one = sve_vq_from_vl(task_get_sve_vl(current)) - 1; - sve_flush_live(true, sve_vq_minus_one); - } -} - void do_el0_svc(struct pt_regs *regs) { - fp_user_discard(); el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table); } #ifdef CONFIG_COMPAT void do_el0_svc_compat(struct pt_regs *regs) { - el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls, + el0_svc_common(regs, regs->regs[7], __NR_compat32_syscalls, compat_sys_call_table); } #endif |