/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/mman.h>
#include <init.h>
#include <as-layout.h>
#include <mm_id.h>
#include <os.h>
#include <ptrace_user.h>
#include <registers.h>
#include <skas.h>
#include <sysdep/ptrace.h>
#include <sysdep/stub.h>

extern char batch_syscall_stub[], __syscall_stub_start[];

extern void wait_stub_done(int pid);

static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
                                              unsigned long *stack)
{
        if (stack == NULL) {
                stack = (unsigned long *) mm_idp->stack + 2;
                *stack = 0;
        }
        return stack;
}

static unsigned long syscall_regs[MAX_REG_NR];

static int __init init_syscall_regs(void)
{
        get_safe_registers(syscall_regs, NULL);
        syscall_regs[REGS_IP_INDEX] = STUB_CODE +
                ((unsigned long) batch_syscall_stub -
                 (unsigned long) __syscall_stub_start);
        return 0;
}

__initcall(init_syscall_regs);

static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
{
        int n, i;
        long ret, offset;
        unsigned long * data;
        unsigned long * syscall;
        int err, pid = mm_idp->u.pid;

        n = ptrace_setregs(pid, syscall_regs);
        if (n < 0) {
                printk(UM_KERN_ERR "Registers - \n");
                for (i = 0; i < MAX_REG_NR; i++)
                        printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
                panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
                      -n);
        }

        err = ptrace(PTRACE_CONT, pid, 0, 0);
        if (err)
                panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
                      errno);

        wait_stub_done(pid);

        /*
         * When the stub stops, we find the following values on the
         * beginning of the stack:
         * (long )return_value
         * (long )offset to failed sycall-data (0, if no error)
         */
        ret = *((unsigned long *) mm_idp->stack);
        offset = *((unsigned long *) mm_idp->stack + 1);
        if (offset) {
                data = (unsigned long *)(mm_idp->stack + offset - STUB_DATA);
                printk(UM_KERN_ERR "do_syscall_stub : ret = %ld, offset = %ld, "
                       "data = %p\n", ret, offset, data);
                syscall = (unsigned long *)((unsigned long)data + data[0]);
                printk(UM_KERN_ERR "do_syscall_stub: syscall %ld failed, "
                       "return value = 0x%lx, expected return value = 0x%lx\n",
                       syscall[0], ret, syscall[7]);
                printk(UM_KERN_ERR "    syscall parameters: "
                       "0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
                       syscall[1], syscall[2], syscall[3],
                       syscall[4], syscall[5], syscall[6]);
                for (n = 1; n < data[0]/sizeof(long); n++) {
                        if (n == 1)
                                printk(UM_KERN_ERR "    additional syscall "
                                       "data:");
                        if (n % 4 == 1)
                                printk("\n" UM_KERN_ERR "      ");
                        printk("  0x%lx", data[n]);
                }
                if (n > 1)
                        printk("\n");
        }
        else ret = 0;

        *addr = check_init_stack(mm_idp, NULL);

        return ret;
}

long run_syscall_stub(struct mm_id * mm_idp, int syscall,
                      unsigned long *args, long expected, void **addr,
                      int done)
{
        unsigned long *stack = check_init_stack(mm_idp, *addr);

        *stack += sizeof(long);
        stack += *stack / sizeof(long);

        *stack++ = syscall;
        *stack++ = args[0];
        *stack++ = args[1];
        *stack++ = args[2];
        *stack++ = args[3];
        *stack++ = args[4];
        *stack++ = args[5];
        *stack++ = expected;
        *stack = 0;

        if (!done && ((((unsigned long) stack) & ~UM_KERN_PAGE_MASK) <
                     UM_KERN_PAGE_SIZE - 10 * sizeof(long))) {
                *addr = stack;
                return 0;
        }

        return do_syscall_stub(mm_idp, addr);
}

long syscall_stub_data(struct mm_id * mm_idp,
                       unsigned long *data, int data_count,
                       void **addr, void **stub_addr)
{
        unsigned long *stack;
        int ret = 0;

        /*
         * If *addr still is uninitialized, it *must* contain NULL.
         * Thus in this case do_syscall_stub correctly won't be called.
         */
        if ((((unsigned long) *addr) & ~UM_KERN_PAGE_MASK) >=
           UM_KERN_PAGE_SIZE - (10 + data_count) * sizeof(long)) {
                ret = do_syscall_stub(mm_idp, addr);
                /* in case of error, don't overwrite data on stack */
                if (ret)
                        return ret;
        }

        stack = check_init_stack(mm_idp, *addr);
        *addr = stack;

        *stack = data_count * sizeof(long);

        memcpy(stack + 1, data, data_count * sizeof(long));

        *stub_addr = (void *)(((unsigned long)(stack + 1) &
                               ~UM_KERN_PAGE_MASK) + STUB_DATA);

        return 0;
}

int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len, int prot,
        int phys_fd, unsigned long long offset, int done, void **data)
{
        int ret;
        unsigned long args[] = { virt, len, prot,
                                 MAP_SHARED | MAP_FIXED, phys_fd,
                                 MMAP_OFFSET(offset) };

        ret = run_syscall_stub(mm_idp, STUB_MMAP_NR, args, virt,
                               data, done);

        return ret;
}

int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
          int done, void **data)
{
        int ret;
        unsigned long args[] = { (unsigned long) addr, len, 0, 0, 0,
                                 0 };

        ret = run_syscall_stub(mm_idp, __NR_munmap, args, 0,
                               data, done);

        return ret;
}

int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
            unsigned int prot, int done, void **data)
{
        int ret;
        unsigned long args[] = { addr, len, prot, 0, 0, 0 };

        ret = run_syscall_stub(mm_idp, __NR_mprotect, args, 0,
                               data, done);

        return ret;
}