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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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3b7142752e
Now that the syscall invocation logic is in C, we can migrate the rest of the syscall entry logic over, so that the entry assembly needn't look at the register values at all. The SVE reset across syscall logic now unconditionally clears TIF_SVE, but sve_user_disable() will only write back to CPACR_EL1 when SVE is actually enabled. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
131 lines
3.1 KiB
C
131 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <linux/context_tracking.h>
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#include <linux/errno.h>
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#include <linux/nospec.h>
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#include <linux/ptrace.h>
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#include <linux/syscalls.h>
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#include <asm/daifflags.h>
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#include <asm/fpsimd.h>
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#include <asm/syscall.h>
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#include <asm/thread_info.h>
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#include <asm/unistd.h>
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long compat_arm_syscall(struct pt_regs *regs);
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asmlinkage long do_ni_syscall(struct pt_regs *regs)
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{
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#ifdef CONFIG_COMPAT
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long ret;
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if (is_compat_task()) {
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ret = compat_arm_syscall(regs);
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if (ret != -ENOSYS)
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return ret;
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}
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#endif
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return sys_ni_syscall();
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}
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static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
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{
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return syscall_fn(regs->regs[0], regs->regs[1], regs->regs[2],
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regs->regs[3], regs->regs[4], regs->regs[5]);
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}
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static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
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unsigned int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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long ret;
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if (scno < sc_nr) {
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syscall_fn_t syscall_fn;
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syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
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ret = __invoke_syscall(regs, syscall_fn);
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} else {
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ret = do_ni_syscall(regs);
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}
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regs->regs[0] = ret;
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}
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static inline bool has_syscall_work(unsigned long flags)
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{
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return unlikely(flags & _TIF_SYSCALL_WORK);
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}
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int syscall_trace_enter(struct pt_regs *regs);
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void syscall_trace_exit(struct pt_regs *regs);
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static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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unsigned long flags = current_thread_info()->flags;
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regs->orig_x0 = regs->regs[0];
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regs->syscallno = scno;
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local_daif_restore(DAIF_PROCCTX);
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user_exit();
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if (has_syscall_work(flags)) {
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/* set default errno for user-issued syscall(-1) */
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if (scno == NO_SYSCALL)
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regs->regs[0] = -ENOSYS;
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scno = syscall_trace_enter(regs);
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if (scno == NO_SYSCALL)
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goto trace_exit;
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}
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invoke_syscall(regs, scno, sc_nr, syscall_table);
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/*
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* The tracing status may have changed under our feet, so we have to
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* check again. However, if we were tracing entry, then we always trace
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* exit regardless, as the old entry assembly did.
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*/
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if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
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local_daif_mask();
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flags = current_thread_info()->flags;
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if (!has_syscall_work(flags))
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return;
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local_daif_restore(DAIF_PROCCTX);
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}
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trace_exit:
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syscall_trace_exit(regs);
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}
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static inline void sve_user_discard(void)
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{
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if (!system_supports_sve())
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return;
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clear_thread_flag(TIF_SVE);
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/*
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* task_fpsimd_load() won't be called to update CPACR_EL1 in
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* ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
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* happens if a context switch or kernel_neon_begin() or context
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* modification (sigreturn, ptrace) intervenes.
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* So, ensure that CPACR_EL1 is already correct for the fast-path case.
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*/
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sve_user_disable();
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}
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asmlinkage void el0_svc_handler(struct pt_regs *regs)
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{
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sve_user_discard();
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el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
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}
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#ifdef CONFIG_COMPAT
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asmlinkage void el0_svc_compat_handler(struct pt_regs *regs)
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{
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el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
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compat_sys_call_table);
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}
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#endif
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