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Diffstat (limited to 'arch/arc/kernel/process.c')
| -rw-r--r-- | arch/arc/kernel/process.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c new file mode 100644 index 000000000..3369f0700 --- /dev/null +++ b/arch/arc/kernel/process.c @@ -0,0 +1,304 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * Amit Bhor, Kanika Nema: Codito Technologies 2004 + */ + +#include <linux/errno.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/sched/task_stack.h> + +#include <linux/mm.h> +#include <linux/fs.h> +#include <linux/unistd.h> +#include <linux/ptrace.h> +#include <linux/slab.h> +#include <linux/syscalls.h> +#include <linux/elf.h> +#include <linux/tick.h> + +#include <asm/fpu.h> + +SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr) +{ + task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr; + return 0; +} + +/* + * We return the user space TLS data ptr as sys-call return code + * Ideally it should be copy to user. + * However we can cheat by the fact that some sys-calls do return + * absurdly high values + * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx + * it won't be considered a sys-call error + * and it will be loads better than copy-to-user, which is a definite + * D-TLB Miss + */ +SYSCALL_DEFINE0(arc_gettls) +{ + return task_thread_info(current)->thr_ptr; +} + +SYSCALL_DEFINE3(arc_usr_cmpxchg, int __user *, uaddr, int, expected, int, new) +{ + struct pt_regs *regs = current_pt_regs(); + u32 uval; + int ret; + + /* + * This is only for old cores lacking LLOCK/SCOND, which by definition + * can't possibly be SMP. Thus doesn't need to be SMP safe. + * And this also helps reduce the overhead for serializing in + * the UP case + */ + WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); + + /* Z indicates to userspace if operation succeeded */ + regs->status32 &= ~STATUS_Z_MASK; + + ret = access_ok(uaddr, sizeof(*uaddr)); + if (!ret) + goto fail; + +again: + preempt_disable(); + + ret = __get_user(uval, uaddr); + if (ret) + goto fault; + + if (uval != expected) + goto out; + + ret = __put_user(new, uaddr); + if (ret) + goto fault; + + regs->status32 |= STATUS_Z_MASK; + +out: + preempt_enable(); + return uval; + +fault: + preempt_enable(); + + if (unlikely(ret != -EFAULT)) + goto fail; + + mmap_read_lock(current->mm); + ret = fixup_user_fault(current->mm, (unsigned long) uaddr, + FAULT_FLAG_WRITE, NULL); + mmap_read_unlock(current->mm); + + if (likely(!ret)) + goto again; + +fail: + force_sig(SIGSEGV); + return ret; +} + +#ifdef CONFIG_ISA_ARCV2 + +void arch_cpu_idle(void) +{ + /* Re-enable interrupts <= default irq priority before committing SLEEP */ + const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; + + __asm__ __volatile__( + "sleep %0 \n" + : + :"I"(arg)); /* can't be "r" has to be embedded const */ +} + +#else /* ARC700 */ + +void arch_cpu_idle(void) +{ + /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ + __asm__ __volatile__("sleep 0x3 \n"); +} + +#endif + +asmlinkage void ret_from_fork(void); + +/* + * Copy architecture-specific thread state + * + * Layout of Child kernel mode stack as setup at the end of this function is + * + * | ... | + * | ... | + * | unused | + * | | + * ------------------ + * | r25 | <==== top of Stack (thread.ksp) + * ~ ~ + * | --to-- | (CALLEE Regs of kernel mode) + * | r13 | + * ------------------ + * | fp | + * | blink | @ret_from_fork + * ------------------ + * | | + * ~ ~ + * ~ ~ + * | | + * ------------------ + * | r12 | + * ~ ~ + * | --to-- | (scratch Regs of user mode) + * | r0 | + * ------------------ + * | SP | + * | orig_r0 | + * | event/ECR | + * | user_r25 | + * ------------------ <===== END of PAGE + */ +int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) +{ + unsigned long clone_flags = args->flags; + unsigned long usp = args->stack; + unsigned long tls = args->tls; + struct pt_regs *c_regs; /* child's pt_regs */ + unsigned long *childksp; /* to unwind out of __switch_to() */ + struct callee_regs *c_callee; /* child's callee regs */ + struct callee_regs *parent_callee; /* paren't callee */ + struct pt_regs *regs = current_pt_regs(); + + /* Mark the specific anchors to begin with (see pic above) */ + c_regs = task_pt_regs(p); + childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ + c_callee = ((struct callee_regs *)childksp) - 1; + + /* + * __switch_to() uses thread.ksp to start unwinding stack + * For kernel threads we don't need to create callee regs, the + * stack layout nevertheless needs to remain the same. + * Also, since __switch_to anyways unwinds callee regs, we use + * this to populate kernel thread entry-pt/args into callee regs, + * so that ret_from_kernel_thread() becomes simpler. + */ + p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */ + + /* __switch_to expects FP(0), BLINK(return addr) at top */ + childksp[0] = 0; /* fp */ + childksp[1] = (unsigned long)ret_from_fork; /* blink */ + + if (unlikely(args->fn)) { + memset(c_regs, 0, sizeof(struct pt_regs)); + + c_callee->r13 = (unsigned long)args->fn_arg; + c_callee->r14 = (unsigned long)args->fn; + + return 0; + } + + /*--------- User Task Only --------------*/ + + /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ + childksp[0] = 0; /* for POP fp */ + childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ + + /* Copy parents pt regs on child's kernel mode stack */ + *c_regs = *regs; + + if (usp) + c_regs->sp = usp; + + c_regs->r0 = 0; /* fork returns 0 in child */ + + parent_callee = ((struct callee_regs *)regs) - 1; + *c_callee = *parent_callee; + + if (unlikely(clone_flags & CLONE_SETTLS)) { + /* + * set task's userland tls data ptr from 4th arg + * clone C-lib call is difft from clone sys-call + */ + task_thread_info(p)->thr_ptr = tls; + } else { + /* Normal fork case: set parent's TLS ptr in child */ + task_thread_info(p)->thr_ptr = + task_thread_info(current)->thr_ptr; + } + + + /* + * setup usermode thread pointer #1: + * when child is picked by scheduler, __switch_to() uses @c_callee to + * populate usermode callee regs: this works (despite being in a kernel + * function) since special return path for child @ret_from_fork() + * ensures those regs are not clobbered all the way to RTIE to usermode + */ + c_callee->r25 = task_thread_info(p)->thr_ptr; + +#ifdef CONFIG_ARC_CURR_IN_REG + /* + * setup usermode thread pointer #2: + * however for this special use of r25 in kernel, __switch_to() sets + * r25 for kernel needs and only in the final return path is usermode + * r25 setup, from pt_regs->user_r25. So set that up as well + */ + c_regs->user_r25 = c_callee->r25; +#endif + + return 0; +} + +/* + * Do necessary setup to start up a new user task + */ +void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) +{ + regs->sp = usp; + regs->ret = pc; + + /* + * [U]ser Mode bit set + * [L] ZOL loop inhibited to begin with - cleared by a LP insn + * Interrupts enabled + */ + regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; + + fpu_init_task(regs); + + /* bogus seed values for debugging */ + regs->lp_start = 0x10; + regs->lp_end = 0x80; +} + +/* + * Some archs flush debug and FPU info here + */ +void flush_thread(void) +{ +} + +int elf_check_arch(const struct elf32_hdr *x) +{ + unsigned int eflags; + + if (x->e_machine != EM_ARC_INUSE) { + pr_err("ELF not built for %s ISA\n", + is_isa_arcompact() ? "ARCompact":"ARCv2"); + return 0; + } + + eflags = x->e_flags; + if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { + pr_err("ABI mismatch - you need newer toolchain\n"); + force_fatal_sig(SIGSEGV); + return 0; + } + + return 1; +} +EXPORT_SYMBOL(elf_check_arch); |