304 lines
7.4 KiB
C
304 lines
7.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* Amit Bhor, Kanika Nema: Codito Technologies 2004
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*/
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/sched/task.h>
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#include <linux/sched/task_stack.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/unistd.h>
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#include <linux/ptrace.h>
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#include <linux/slab.h>
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#include <linux/syscalls.h>
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#include <linux/elf.h>
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#include <linux/tick.h>
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#include <asm/fpu.h>
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SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
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{
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task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
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return 0;
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}
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/*
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* We return the user space TLS data ptr as sys-call return code
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* Ideally it should be copy to user.
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* However we can cheat by the fact that some sys-calls do return
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* absurdly high values
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* Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx
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* it won't be considered a sys-call error
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* and it will be loads better than copy-to-user, which is a definite
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* D-TLB Miss
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*/
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SYSCALL_DEFINE0(arc_gettls)
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{
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return task_thread_info(current)->thr_ptr;
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}
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SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new)
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{
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struct pt_regs *regs = current_pt_regs();
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u32 uval;
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int ret;
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/*
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* This is only for old cores lacking LLOCK/SCOND, which by definition
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* can't possibly be SMP. Thus doesn't need to be SMP safe.
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* And this also helps reduce the overhead for serializing in
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* the UP case
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*/
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WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP));
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/* Z indicates to userspace if operation succeeded */
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regs->status32 &= ~STATUS_Z_MASK;
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ret = access_ok(uaddr, sizeof(*uaddr));
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if (!ret)
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goto fail;
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again:
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preempt_disable();
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ret = __get_user(uval, uaddr);
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if (ret)
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goto fault;
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if (uval != expected)
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goto out;
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ret = __put_user(new, uaddr);
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if (ret)
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goto fault;
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regs->status32 |= STATUS_Z_MASK;
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out:
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preempt_enable();
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return uval;
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fault:
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preempt_enable();
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if (unlikely(ret != -EFAULT))
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goto fail;
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mmap_read_lock(current->mm);
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ret = fixup_user_fault(current->mm, (unsigned long) uaddr,
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FAULT_FLAG_WRITE, NULL);
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mmap_read_unlock(current->mm);
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if (likely(!ret))
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goto again;
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fail:
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force_sig(SIGSEGV);
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return ret;
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}
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#ifdef CONFIG_ISA_ARCV2
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void arch_cpu_idle(void)
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{
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/* Re-enable interrupts <= default irq priority before committing SLEEP */
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const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO;
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__asm__ __volatile__(
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"sleep %0 \n"
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:
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:"I"(arg)); /* can't be "r" has to be embedded const */
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}
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#else /* ARC700 */
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void arch_cpu_idle(void)
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{
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/* sleep, but enable both set E1/E2 (levels of interrupts) before committing */
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__asm__ __volatile__("sleep 0x3 \n");
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}
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#endif
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asmlinkage void ret_from_fork(void);
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/*
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* Copy architecture-specific thread state
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*
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* Layout of Child kernel mode stack as setup at the end of this function is
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*
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* | ... |
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* | ... |
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* | unused |
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* | |
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* ------------------
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* | r25 | <==== top of Stack (thread.ksp)
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* ~ ~
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* | --to-- | (CALLEE Regs of kernel mode)
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* | r13 |
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* ------------------
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* | fp |
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* | blink | @ret_from_fork
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* ------------------
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* | |
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* ~ ~
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* ~ ~
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* | |
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* ------------------
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* | r12 |
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* ~ ~
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* | --to-- | (scratch Regs of user mode)
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* | r0 |
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* ------------------
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* | SP |
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* | orig_r0 |
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* | event/ECR |
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* | user_r25 |
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* ------------------ <===== END of PAGE
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*/
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int copy_thread(unsigned long clone_flags, unsigned long usp,
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unsigned long kthread_arg, struct task_struct *p,
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unsigned long tls)
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{
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struct pt_regs *c_regs; /* child's pt_regs */
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unsigned long *childksp; /* to unwind out of __switch_to() */
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struct callee_regs *c_callee; /* child's callee regs */
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struct callee_regs *parent_callee; /* paren't callee */
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struct pt_regs *regs = current_pt_regs();
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/* Mark the specific anchors to begin with (see pic above) */
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c_regs = task_pt_regs(p);
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childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
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c_callee = ((struct callee_regs *)childksp) - 1;
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/*
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* __switch_to() uses thread.ksp to start unwinding stack
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* For kernel threads we don't need to create callee regs, the
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* stack layout nevertheless needs to remain the same.
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* Also, since __switch_to anyways unwinds callee regs, we use
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* this to populate kernel thread entry-pt/args into callee regs,
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* so that ret_from_kernel_thread() becomes simpler.
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*/
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p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
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/* __switch_to expects FP(0), BLINK(return addr) at top */
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childksp[0] = 0; /* fp */
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childksp[1] = (unsigned long)ret_from_fork; /* blink */
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if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
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memset(c_regs, 0, sizeof(struct pt_regs));
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c_callee->r13 = kthread_arg;
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c_callee->r14 = usp; /* function */
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return 0;
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}
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/*--------- User Task Only --------------*/
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/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
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childksp[0] = 0; /* for POP fp */
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childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
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/* Copy parents pt regs on child's kernel mode stack */
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*c_regs = *regs;
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if (usp)
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c_regs->sp = usp;
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c_regs->r0 = 0; /* fork returns 0 in child */
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parent_callee = ((struct callee_regs *)regs) - 1;
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*c_callee = *parent_callee;
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if (unlikely(clone_flags & CLONE_SETTLS)) {
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/*
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* set task's userland tls data ptr from 4th arg
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* clone C-lib call is difft from clone sys-call
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*/
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task_thread_info(p)->thr_ptr = tls;
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} else {
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/* Normal fork case: set parent's TLS ptr in child */
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task_thread_info(p)->thr_ptr =
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task_thread_info(current)->thr_ptr;
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}
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/*
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* setup usermode thread pointer #1:
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* when child is picked by scheduler, __switch_to() uses @c_callee to
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* populate usermode callee regs: this works (despite being in a kernel
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* function) since special return path for child @ret_from_fork()
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* ensures those regs are not clobbered all the way to RTIE to usermode
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*/
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c_callee->r25 = task_thread_info(p)->thr_ptr;
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#ifdef CONFIG_ARC_CURR_IN_REG
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/*
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* setup usermode thread pointer #2:
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* however for this special use of r25 in kernel, __switch_to() sets
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* r25 for kernel needs and only in the final return path is usermode
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* r25 setup, from pt_regs->user_r25. So set that up as well
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*/
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c_regs->user_r25 = c_callee->r25;
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#endif
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return 0;
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}
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/*
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* Do necessary setup to start up a new user task
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*/
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void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
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{
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regs->sp = usp;
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regs->ret = pc;
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/*
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* [U]ser Mode bit set
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* [L] ZOL loop inhibited to begin with - cleared by a LP insn
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* Interrupts enabled
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*/
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regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
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fpu_init_task(regs);
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/* bogus seed values for debugging */
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regs->lp_start = 0x10;
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regs->lp_end = 0x80;
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}
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/*
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* Some archs flush debug and FPU info here
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*/
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void flush_thread(void)
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{
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}
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int elf_check_arch(const struct elf32_hdr *x)
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{
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unsigned int eflags;
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if (x->e_machine != EM_ARC_INUSE) {
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pr_err("ELF not built for %s ISA\n",
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is_isa_arcompact() ? "ARCompact":"ARCv2");
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return 0;
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}
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eflags = x->e_flags;
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if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
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pr_err("ABI mismatch - you need newer toolchain\n");
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force_fatal_sig(SIGSEGV);
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return 0;
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}
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return 1;
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}
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EXPORT_SYMBOL(elf_check_arch);
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