1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/mm.h>
 16#include <linux/pagemap.h>
 17#include <linux/binfmts.h>
 18#include <linux/compat.h>
 19#include <linux/mman.h>
 20#include <linux/elf.h>
 21#include <asm/pgtable.h>
 22#include <asm/pgalloc.h>
 23#include <asm/sections.h>
 24
 25/* Notify a running simulator, if any, that an exec just occurred. */
 26static void sim_notify_exec(const char *binary_name)
 27{
 28	unsigned char c;
 29	do {
 30		c = *binary_name++;
 31		__insn_mtspr(SPR_SIM_CONTROL,
 32			     (SIM_CONTROL_OS_EXEC
 33			      | (c << _SIM_CONTROL_OPERATOR_BITS)));
 34
 35	} while (c);
 36}
 37
 38static int notify_exec(void)
 39{
 40	int retval = 0;  /* failure */
 41	struct vm_area_struct *vma = current->mm->mmap;
 42	while (vma) {
 43		if ((vma->vm_flags & VM_EXECUTABLE) && vma->vm_file)
 44			break;
 45		vma = vma->vm_next;
 46	}
 47	if (vma) {
 48		char *buf = (char *) __get_free_page(GFP_KERNEL);
 49		if (buf) {
 50			char *path = d_path(&vma->vm_file->f_path,
 51					    buf, PAGE_SIZE);
 52			if (!IS_ERR(path)) {
 53				sim_notify_exec(path);
 54				retval = 1;
 55			}
 56			free_page((unsigned long)buf);
 57		}
 58	}
 59	return retval;
 60}
 61
 62/* Notify a running simulator, if any, that we loaded an interpreter. */
 63static void sim_notify_interp(unsigned long load_addr)
 64{
 65	size_t i;
 66	for (i = 0; i < sizeof(load_addr); i++) {
 67		unsigned char c = load_addr >> (i * 8);
 68		__insn_mtspr(SPR_SIM_CONTROL,
 69			     (SIM_CONTROL_OS_INTERP
 70			      | (c << _SIM_CONTROL_OPERATOR_BITS)));
 71	}
 72}
 73
 74
 75/* Kernel address of page used to map read-only kernel data into userspace. */
 76static void *vdso_page;
 77
 78/* One-entry array used for install_special_mapping. */
 79static struct page *vdso_pages[1];
 80
 81static int __init vdso_setup(void)
 82{
 83	vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
 84	memcpy(vdso_page, __rt_sigreturn, __rt_sigreturn_end - __rt_sigreturn);
 85	vdso_pages[0] = virt_to_page(vdso_page);
 86	return 0;
 87}
 88device_initcall(vdso_setup);
 89
 90const char *arch_vma_name(struct vm_area_struct *vma)
 91{
 92	if (vma->vm_private_data == vdso_pages)
 93		return "[vdso]";
 94#ifndef __tilegx__
 95	if (vma->vm_start == MEM_USER_INTRPT)
 96		return "[intrpt]";
 97#endif
 98	return NULL;
 99}
100
101int arch_setup_additional_pages(struct linux_binprm *bprm,
102				int executable_stack)
103{
104	struct mm_struct *mm = current->mm;
105	unsigned long vdso_base;
106	int retval = 0;
107
108	/*
109	 * Notify the simulator that an exec just occurred.
110	 * If we can't find the filename of the mapping, just use
111	 * whatever was passed as the linux_binprm filename.
112	 */
113	if (!notify_exec())
114		sim_notify_exec(bprm->filename);
115
116	down_write(&mm->mmap_sem);
117
118	/*
119	 * MAYWRITE to allow gdb to COW and set breakpoints
120	 *
121	 * Make sure the vDSO gets into every core dump.  Dumping its
122	 * contents makes post-mortem fully interpretable later
123	 * without matching up the same kernel and hardware config to
124	 * see what PC values meant.
125	 */
126	vdso_base = VDSO_BASE;
127	retval = install_special_mapping(mm, vdso_base, PAGE_SIZE,
128					 VM_READ|VM_EXEC|
129					 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
130					 VM_ALWAYSDUMP,
131					 vdso_pages);
132
133#ifndef __tilegx__
134	/*
135	 * Set up a user-interrupt mapping here; the user can't
136	 * create one themselves since it is above TASK_SIZE.
137	 * We make it unwritable by default, so the model for adding
138	 * interrupt vectors always involves an mprotect.
139	 */
140	if (!retval) {
141		unsigned long addr = MEM_USER_INTRPT;
142		addr = mmap_region(NULL, addr, INTRPT_SIZE,
143				   MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE,
144				   VM_READ|VM_EXEC|
145				   VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0);
146		if (addr > (unsigned long) -PAGE_SIZE)
147			retval = (int) addr;
148	}
149#endif
150
151	up_write(&mm->mmap_sem);
152
153	return retval;
154}
155
156
157void elf_plat_init(struct pt_regs *regs, unsigned long load_addr)
158{
159	/* Zero all registers. */
160	memset(regs, 0, sizeof(*regs));
161
162	/* Report the interpreter's load address. */
163	sim_notify_interp(load_addr);
164}