From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: AndrĂ© Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/x86/um/ldt.c | 371 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 371 insertions(+) create mode 100644 arch/x86/um/ldt.c (limited to 'arch/x86/um/ldt.c') diff --git a/arch/x86/um/ldt.c b/arch/x86/um/ldt.c new file mode 100644 index 000000000..5c0b711d2 --- /dev/null +++ b/arch/x86/um/ldt.c @@ -0,0 +1,371 @@ +/* + * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + */ + +#include +#include +#include +#include +#include +#include +#include + +extern int modify_ldt(int func, void *ptr, unsigned long bytecount); + +static long write_ldt_entry(struct mm_id *mm_idp, int func, + struct user_desc *desc, void **addr, int done) +{ + long res; + void *stub_addr; + res = syscall_stub_data(mm_idp, (unsigned long *)desc, + (sizeof(*desc) + sizeof(long) - 1) & + ~(sizeof(long) - 1), + addr, &stub_addr); + if (!res) { + unsigned long args[] = { func, + (unsigned long)stub_addr, + sizeof(*desc), + 0, 0, 0 }; + res = run_syscall_stub(mm_idp, __NR_modify_ldt, args, + 0, addr, done); + } + + return res; +} + +/* + * In skas mode, we hold our own ldt data in UML. + * Thus, the code implementing sys_modify_ldt_skas + * is very similar to (and mostly stolen from) sys_modify_ldt + * for arch/i386/kernel/ldt.c + * The routines copied and modified in part are: + * - read_ldt + * - read_default_ldt + * - write_ldt + * - sys_modify_ldt_skas + */ + +static int read_ldt(void __user * ptr, unsigned long bytecount) +{ + int i, err = 0; + unsigned long size; + uml_ldt_t *ldt = ¤t->mm->context.arch.ldt; + + if (!ldt->entry_count) + goto out; + if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES) + bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES; + err = bytecount; + + mutex_lock(&ldt->lock); + if (ldt->entry_count <= LDT_DIRECT_ENTRIES) { + size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES; + if (size > bytecount) + size = bytecount; + if (copy_to_user(ptr, ldt->u.entries, size)) + err = -EFAULT; + bytecount -= size; + ptr += size; + } + else { + for (i=0; ientry_count/LDT_ENTRIES_PER_PAGE && bytecount; + i++) { + size = PAGE_SIZE; + if (size > bytecount) + size = bytecount; + if (copy_to_user(ptr, ldt->u.pages[i], size)) { + err = -EFAULT; + break; + } + bytecount -= size; + ptr += size; + } + } + mutex_unlock(&ldt->lock); + + if (bytecount == 0 || err == -EFAULT) + goto out; + + if (clear_user(ptr, bytecount)) + err = -EFAULT; + +out: + return err; +} + +static int read_default_ldt(void __user * ptr, unsigned long bytecount) +{ + int err; + + if (bytecount > 5*LDT_ENTRY_SIZE) + bytecount = 5*LDT_ENTRY_SIZE; + + err = bytecount; + /* + * UML doesn't support lcall7 and lcall27. + * So, we don't really have a default ldt, but emulate + * an empty ldt of common host default ldt size. + */ + if (clear_user(ptr, bytecount)) + err = -EFAULT; + + return err; +} + +static int write_ldt(void __user * ptr, unsigned long bytecount, int func) +{ + uml_ldt_t *ldt = ¤t->mm->context.arch.ldt; + struct mm_id * mm_idp = ¤t->mm->context.id; + int i, err; + struct user_desc ldt_info; + struct ldt_entry entry0, *ldt_p; + void *addr = NULL; + + err = -EINVAL; + if (bytecount != sizeof(ldt_info)) + goto out; + err = -EFAULT; + if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) + goto out; + + err = -EINVAL; + if (ldt_info.entry_number >= LDT_ENTRIES) + goto out; + if (ldt_info.contents == 3) { + if (func == 1) + goto out; + if (ldt_info.seg_not_present == 0) + goto out; + } + + mutex_lock(&ldt->lock); + + err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1); + if (err) + goto out_unlock; + + if (ldt_info.entry_number >= ldt->entry_count && + ldt_info.entry_number >= LDT_DIRECT_ENTRIES) { + for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE; + i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number; + i++) { + if (i == 0) + memcpy(&entry0, ldt->u.entries, + sizeof(entry0)); + ldt->u.pages[i] = (struct ldt_entry *) + __get_free_page(GFP_KERNEL|__GFP_ZERO); + if (!ldt->u.pages[i]) { + err = -ENOMEM; + /* Undo the change in host */ + memset(&ldt_info, 0, sizeof(ldt_info)); + write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1); + goto out_unlock; + } + if (i == 0) { + memcpy(ldt->u.pages[0], &entry0, + sizeof(entry0)); + memcpy(ldt->u.pages[0]+1, ldt->u.entries+1, + sizeof(entry0)*(LDT_DIRECT_ENTRIES-1)); + } + ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE; + } + } + if (ldt->entry_count <= ldt_info.entry_number) + ldt->entry_count = ldt_info.entry_number + 1; + + if (ldt->entry_count <= LDT_DIRECT_ENTRIES) + ldt_p = ldt->u.entries + ldt_info.entry_number; + else + ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] + + ldt_info.entry_number%LDT_ENTRIES_PER_PAGE; + + if (ldt_info.base_addr == 0 && ldt_info.limit == 0 && + (func == 1 || LDT_empty(&ldt_info))) { + ldt_p->a = 0; + ldt_p->b = 0; + } + else{ + if (func == 1) + ldt_info.useable = 0; + ldt_p->a = LDT_entry_a(&ldt_info); + ldt_p->b = LDT_entry_b(&ldt_info); + } + err = 0; + +out_unlock: + mutex_unlock(&ldt->lock); +out: + return err; +} + +static long do_modify_ldt_skas(int func, void __user *ptr, + unsigned long bytecount) +{ + int ret = -ENOSYS; + + switch (func) { + case 0: + ret = read_ldt(ptr, bytecount); + break; + case 1: + case 0x11: + ret = write_ldt(ptr, bytecount, func); + break; + case 2: + ret = read_default_ldt(ptr, bytecount); + break; + } + return ret; +} + +static DEFINE_SPINLOCK(host_ldt_lock); +static short dummy_list[9] = {0, -1}; +static short * host_ldt_entries = NULL; + +static void ldt_get_host_info(void) +{ + long ret; + struct ldt_entry * ldt; + short *tmp; + int i, size, k, order; + + spin_lock(&host_ldt_lock); + + if (host_ldt_entries != NULL) { + spin_unlock(&host_ldt_lock); + return; + } + host_ldt_entries = dummy_list+1; + + spin_unlock(&host_ldt_lock); + + for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++) + ; + + ldt = (struct ldt_entry *) + __get_free_pages(GFP_KERNEL|__GFP_ZERO, order); + if (ldt == NULL) { + printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer " + "for host ldt\n"); + return; + } + + ret = modify_ldt(0, ldt, (1<arch.ldt.lock); + + if (!from_mm) { + memset(&desc, 0, sizeof(desc)); + /* + * Now we try to retrieve info about the ldt, we + * inherited from the host. All ldt-entries found + * will be reset in the following loop + */ + ldt_get_host_info(); + for (num_p=host_ldt_entries; *num_p != -1; num_p++) { + desc.entry_number = *num_p; + err = write_ldt_entry(&new_mm->id, 1, &desc, + &addr, *(num_p + 1) == -1); + if (err) + break; + } + new_mm->arch.ldt.entry_count = 0; + + goto out; + } + + /* + * Our local LDT is used to supply the data for + * modify_ldt(READLDT), if PTRACE_LDT isn't available, + * i.e., we have to use the stub for modify_ldt, which + * can't handle the big read buffer of up to 64kB. + */ + mutex_lock(&from_mm->arch.ldt.lock); + if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES) + memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries, + sizeof(new_mm->arch.ldt.u.entries)); + else { + i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE; + while (i-->0) { + page = __get_free_page(GFP_KERNEL|__GFP_ZERO); + if (!page) { + err = -ENOMEM; + break; + } + new_mm->arch.ldt.u.pages[i] = + (struct ldt_entry *) page; + memcpy(new_mm->arch.ldt.u.pages[i], + from_mm->arch.ldt.u.pages[i], PAGE_SIZE); + } + } + new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count; + mutex_unlock(&from_mm->arch.ldt.lock); + + out: + return err; +} + + +void free_ldt(struct mm_context *mm) +{ + int i; + + if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) { + i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE; + while (i-- > 0) + free_page((long) mm->arch.ldt.u.pages[i]); + } + mm->arch.ldt.entry_count = 0; +} + +int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount) +{ + return do_modify_ldt_skas(func, ptr, bytecount); +} -- cgit v1.2.3-54-g00ecf