c742b31c03
The extract cpu time instruction (ectg) instruction allows the user process to get the current thread cputime without calling into the kernel. The code that uses the instruction needs to switch to the access registers mode to get access to the per-cpu info page that contains the two base values that are needed to calculate the current cputime from the CPU timer with the ectg instruction. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
352 lines
8.5 KiB
C
352 lines
8.5 KiB
C
/*
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* vdso setup for s390
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/slab.h>
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#include <linux/user.h>
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#include <linux/elf.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/processor.h>
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#include <asm/mmu.h>
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#include <asm/mmu_context.h>
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#include <asm/sections.h>
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#include <asm/vdso.h>
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#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
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extern char vdso32_start, vdso32_end;
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static void *vdso32_kbase = &vdso32_start;
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static unsigned int vdso32_pages;
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static struct page **vdso32_pagelist;
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#endif
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#ifdef CONFIG_64BIT
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extern char vdso64_start, vdso64_end;
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static void *vdso64_kbase = &vdso64_start;
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static unsigned int vdso64_pages;
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static struct page **vdso64_pagelist;
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#endif /* CONFIG_64BIT */
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso_enabled = 1;
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static int __init vdso_setup(char *s)
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{
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vdso_enabled = simple_strtoul(s, NULL, 0);
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return 1;
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}
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__setup("vdso=", vdso_setup);
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/*
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* The vdso data page
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*/
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static union {
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struct vdso_data data;
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u8 page[PAGE_SIZE];
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} vdso_data_store __attribute__((__section__(".data.page_aligned")));
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struct vdso_data *vdso_data = &vdso_data_store.data;
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/*
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* Setup vdso data page.
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*/
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static void vdso_init_data(struct vdso_data *vd)
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{
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unsigned int facility_list;
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facility_list = stfl();
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vd->ectg_available = switch_amode && (facility_list & 1);
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}
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#ifdef CONFIG_64BIT
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/*
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* Setup per cpu vdso data page.
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*/
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static void vdso_init_per_cpu_data(int cpu, struct vdso_per_cpu_data *vpcd)
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{
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}
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/*
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* Allocate/free per cpu vdso data.
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*/
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#ifdef CONFIG_64BIT
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#define SEGMENT_ORDER 2
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#else
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#define SEGMENT_ORDER 1
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#endif
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int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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u32 *psal, *aste;
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int i;
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lowcore->vdso_per_cpu_data = __LC_PASTE;
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if (!switch_amode || !vdso_enabled)
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return 0;
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segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
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page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
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page_frame = get_zeroed_page(GFP_KERNEL);
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if (!segment_table || !page_table || !page_frame)
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goto out;
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clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
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PAGE_SIZE << SEGMENT_ORDER);
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clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY,
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256*sizeof(unsigned long));
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*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
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*(unsigned long *) page_table = _PAGE_RO + page_frame;
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psal = (u32 *) (page_table + 256*sizeof(unsigned long));
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aste = psal + 32;
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for (i = 4; i < 32; i += 4)
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psal[i] = 0x80000000;
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lowcore->paste[4] = (u32)(addr_t) psal;
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psal[0] = 0x20000000;
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psal[2] = (u32)(addr_t) aste;
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*(unsigned long *) (aste + 2) = segment_table +
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_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
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aste[4] = (u32)(addr_t) psal;
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lowcore->vdso_per_cpu_data = page_frame;
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vdso_init_per_cpu_data(cpu, (struct vdso_per_cpu_data *) page_frame);
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return 0;
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out:
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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return -ENOMEM;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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u32 *psal, *aste;
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if (!switch_amode || !vdso_enabled)
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return;
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psal = (u32 *)(addr_t) lowcore->paste[4];
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aste = (u32 *)(addr_t) psal[2];
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segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
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page_table = *(unsigned long *) segment_table;
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page_frame = *(unsigned long *) page_table;
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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static void __vdso_init_cr5(void *dummy)
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{
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unsigned long cr5;
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cr5 = offsetof(struct _lowcore, paste);
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__ctl_load(cr5, 5, 5);
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}
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static void vdso_init_cr5(void)
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{
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if (switch_amode && vdso_enabled)
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on_each_cpu(__vdso_init_cr5, NULL, 1);
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}
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#endif /* CONFIG_64BIT */
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/*
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* This is called from binfmt_elf, we create the special vma for the
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* vDSO and insert it into the mm struct tree
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*/
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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struct page **vdso_pagelist;
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unsigned long vdso_pages;
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unsigned long vdso_base;
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int rc;
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if (!vdso_enabled)
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return 0;
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/*
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* Only map the vdso for dynamically linked elf binaries.
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*/
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if (!uses_interp)
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return 0;
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vdso_base = mm->mmap_base;
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#ifdef CONFIG_64BIT
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vdso_pagelist = vdso64_pagelist;
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vdso_pages = vdso64_pages;
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#ifdef CONFIG_COMPAT
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if (test_thread_flag(TIF_31BIT)) {
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vdso_pagelist = vdso32_pagelist;
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vdso_pages = vdso32_pages;
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}
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#endif
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#else
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vdso_pagelist = vdso32_pagelist;
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vdso_pages = vdso32_pages;
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#endif
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/*
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* vDSO has a problem and was disabled, just don't "enable" it for
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* the process
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*/
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if (vdso_pages == 0)
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return 0;
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current->mm->context.vdso_base = 0;
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/*
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* pick a base address for the vDSO in process space. We try to put
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* it at vdso_base which is the "natural" base for it, but we might
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* fail and end up putting it elsewhere.
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*/
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down_write(&mm->mmap_sem);
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vdso_base = get_unmapped_area(NULL, vdso_base,
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vdso_pages << PAGE_SHIFT, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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rc = vdso_base;
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goto out_up;
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}
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/*
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* our vma flags don't have VM_WRITE so by default, the process
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* isn't allowed to write those pages.
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* gdb can break that with ptrace interface, and thus trigger COW
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* on those pages but it's then your responsibility to never do that
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* on the "data" page of the vDSO or you'll stop getting kernel
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* updates and your nice userland gettimeofday will be totally dead.
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* It's fine to use that for setting breakpoints in the vDSO code
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* pages though
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*
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* Make sure the vDSO gets into every core dump.
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* Dumping its contents makes post-mortem fully interpretable later
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* without matching up the same kernel and hardware config to see
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* what PC values meant.
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*/
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rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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vdso_pagelist);
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if (rc)
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goto out_up;
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/* Put vDSO base into mm struct */
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current->mm->context.vdso_base = vdso_base;
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up_write(&mm->mmap_sem);
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return 0;
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out_up:
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up_write(&mm->mmap_sem);
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return rc;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
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return "[vdso]";
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return NULL;
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}
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static int __init vdso_init(void)
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{
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int i;
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if (!vdso_enabled)
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return 0;
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vdso_init_data(vdso_data);
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#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
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/* Calculate the size of the 32 bit vDSO */
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vdso32_pages = ((&vdso32_end - &vdso32_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso32_pagelist == NULL);
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for (i = 0; i < vdso32_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso32_pagelist[i] = pg;
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}
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vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
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vdso32_pagelist[vdso32_pages] = NULL;
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#endif
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#ifdef CONFIG_64BIT
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/* Calculate the size of the 64 bit vDSO */
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vdso64_pages = ((&vdso64_end - &vdso64_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso64_pagelist == NULL);
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for (i = 0; i < vdso64_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso64_pagelist[i] = pg;
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}
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vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
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vdso64_pagelist[vdso64_pages] = NULL;
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#ifndef CONFIG_SMP
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BUG_ON(vdso_alloc_per_cpu(0, S390_lowcore));
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#endif
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vdso_init_cr5();
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#endif /* CONFIG_64BIT */
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get_page(virt_to_page(vdso_data));
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smp_wmb();
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return 0;
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}
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arch_initcall(vdso_init);
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int in_gate_area_no_task(unsigned long addr)
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{
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return 0;
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}
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int in_gate_area(struct task_struct *task, unsigned long addr)
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{
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return 0;
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}
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struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
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{
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return NULL;
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}
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