// 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 */
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)
{
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_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);