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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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 */
raw_local_irq_disable();}
#else /* ARC700 */
void arch_cpu_idle(void){ /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ __asm__ __volatile__("sleep 0x3 \n"); raw_local_irq_disable();}
#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_info.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 | * ------------------ <===== END of PAGE */int copy_thread(struct task_struct *p, const struct kernel_clone_args *args){ u64 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_info.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. */ task_thread_info(p)->ksp = (unsigned long)c_callee; /* THREAD_INFO_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;
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);