![Andy Lutomirski](/assets/img/avatar_default.png)
We use __read_cr4() vs __read_cr4_safe() inconsistently. On CR4-less CPUs, all CR4 bits are effectively clear, so we can make the code simpler and more robust by making __read_cr4() always fix up faults on 32-bit kernels. This may fix some bugs on old 486-like CPUs, but I don't have any easy way to test that. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: david@saggiorato.net Link: http://lkml.kernel.org/r/ea647033d357d9ce2ad2bbde5a631045f5052fb6.1475178370.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
465 lines
11 KiB
C
465 lines
11 KiB
C
/* Paravirtualization interfaces
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Copyright (C) 2006 Rusty Russell IBM Corporation
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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 as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
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*/
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/efi.h>
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#include <linux/bcd.h>
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#include <linux/highmem.h>
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#include <linux/kprobes.h>
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#include <asm/bug.h>
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#include <asm/paravirt.h>
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#include <asm/debugreg.h>
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#include <asm/desc.h>
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#include <asm/setup.h>
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#include <asm/pgtable.h>
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#include <asm/time.h>
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#include <asm/pgalloc.h>
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#include <asm/irq.h>
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#include <asm/delay.h>
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#include <asm/fixmap.h>
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#include <asm/apic.h>
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#include <asm/tlbflush.h>
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#include <asm/timer.h>
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#include <asm/special_insns.h>
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/*
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* nop stub, which must not clobber anything *including the stack* to
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* avoid confusing the entry prologues.
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*/
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extern void _paravirt_nop(void);
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asm (".pushsection .entry.text, \"ax\"\n"
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".global _paravirt_nop\n"
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"_paravirt_nop:\n\t"
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"ret\n\t"
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".size _paravirt_nop, . - _paravirt_nop\n\t"
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".type _paravirt_nop, @function\n\t"
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".popsection");
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/* identity function, which can be inlined */
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u32 notrace _paravirt_ident_32(u32 x)
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{
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return x;
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}
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u64 notrace _paravirt_ident_64(u64 x)
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{
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return x;
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}
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void __init default_banner(void)
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{
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printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
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pv_info.name);
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}
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/* Undefined instruction for dealing with missing ops pointers. */
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static const unsigned char ud2a[] = { 0x0f, 0x0b };
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struct branch {
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unsigned char opcode;
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u32 delta;
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} __attribute__((packed));
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unsigned paravirt_patch_call(void *insnbuf,
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const void *target, u16 tgt_clobbers,
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unsigned long addr, u16 site_clobbers,
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unsigned len)
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{
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struct branch *b = insnbuf;
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unsigned long delta = (unsigned long)target - (addr+5);
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if (tgt_clobbers & ~site_clobbers)
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return len; /* target would clobber too much for this site */
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if (len < 5)
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return len; /* call too long for patch site */
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b->opcode = 0xe8; /* call */
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b->delta = delta;
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BUILD_BUG_ON(sizeof(*b) != 5);
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return 5;
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}
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unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
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unsigned long addr, unsigned len)
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{
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struct branch *b = insnbuf;
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unsigned long delta = (unsigned long)target - (addr+5);
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if (len < 5)
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return len; /* call too long for patch site */
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b->opcode = 0xe9; /* jmp */
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b->delta = delta;
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return 5;
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}
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/* Neat trick to map patch type back to the call within the
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* corresponding structure. */
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static void *get_call_destination(u8 type)
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{
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struct paravirt_patch_template tmpl = {
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.pv_init_ops = pv_init_ops,
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.pv_time_ops = pv_time_ops,
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.pv_cpu_ops = pv_cpu_ops,
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.pv_irq_ops = pv_irq_ops,
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.pv_mmu_ops = pv_mmu_ops,
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#ifdef CONFIG_PARAVIRT_SPINLOCKS
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.pv_lock_ops = pv_lock_ops,
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#endif
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};
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return *((void **)&tmpl + type);
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}
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unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
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unsigned long addr, unsigned len)
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{
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void *opfunc = get_call_destination(type);
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unsigned ret;
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if (opfunc == NULL)
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/* If there's no function, patch it with a ud2a (BUG) */
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ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
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else if (opfunc == _paravirt_nop)
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ret = 0;
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/* identity functions just return their single argument */
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else if (opfunc == _paravirt_ident_32)
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ret = paravirt_patch_ident_32(insnbuf, len);
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else if (opfunc == _paravirt_ident_64)
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ret = paravirt_patch_ident_64(insnbuf, len);
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else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
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type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
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/* If operation requires a jmp, then jmp */
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ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
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else
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/* Otherwise call the function; assume target could
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clobber any caller-save reg */
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ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
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addr, clobbers, len);
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return ret;
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}
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unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
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const char *start, const char *end)
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{
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unsigned insn_len = end - start;
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if (insn_len > len || start == NULL)
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insn_len = len;
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else
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memcpy(insnbuf, start, insn_len);
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return insn_len;
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}
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static void native_flush_tlb(void)
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{
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__native_flush_tlb();
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}
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/*
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* Global pages have to be flushed a bit differently. Not a real
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* performance problem because this does not happen often.
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*/
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static void native_flush_tlb_global(void)
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{
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__native_flush_tlb_global();
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}
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static void native_flush_tlb_single(unsigned long addr)
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{
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__native_flush_tlb_single(addr);
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}
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struct static_key paravirt_steal_enabled;
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struct static_key paravirt_steal_rq_enabled;
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static u64 native_steal_clock(int cpu)
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{
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return 0;
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}
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/* These are in entry.S */
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extern void native_iret(void);
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extern void native_usergs_sysret64(void);
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static struct resource reserve_ioports = {
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.start = 0,
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.end = IO_SPACE_LIMIT,
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.name = "paravirt-ioport",
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.flags = IORESOURCE_IO | IORESOURCE_BUSY,
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};
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/*
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* Reserve the whole legacy IO space to prevent any legacy drivers
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* from wasting time probing for their hardware. This is a fairly
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* brute-force approach to disabling all non-virtual drivers.
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*
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* Note that this must be called very early to have any effect.
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*/
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int paravirt_disable_iospace(void)
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{
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return request_resource(&ioport_resource, &reserve_ioports);
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}
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static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
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static inline void enter_lazy(enum paravirt_lazy_mode mode)
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{
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BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
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this_cpu_write(paravirt_lazy_mode, mode);
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}
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static void leave_lazy(enum paravirt_lazy_mode mode)
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{
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BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
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this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
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}
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void paravirt_enter_lazy_mmu(void)
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{
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enter_lazy(PARAVIRT_LAZY_MMU);
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}
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void paravirt_leave_lazy_mmu(void)
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{
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leave_lazy(PARAVIRT_LAZY_MMU);
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}
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void paravirt_flush_lazy_mmu(void)
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{
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preempt_disable();
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if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
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arch_leave_lazy_mmu_mode();
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arch_enter_lazy_mmu_mode();
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}
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preempt_enable();
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}
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void paravirt_start_context_switch(struct task_struct *prev)
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{
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BUG_ON(preemptible());
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if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
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arch_leave_lazy_mmu_mode();
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set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
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}
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enter_lazy(PARAVIRT_LAZY_CPU);
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}
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void paravirt_end_context_switch(struct task_struct *next)
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{
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BUG_ON(preemptible());
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leave_lazy(PARAVIRT_LAZY_CPU);
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if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
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arch_enter_lazy_mmu_mode();
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}
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enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
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{
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if (in_interrupt())
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return PARAVIRT_LAZY_NONE;
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return this_cpu_read(paravirt_lazy_mode);
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}
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struct pv_info pv_info = {
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.name = "bare hardware",
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.kernel_rpl = 0,
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.shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
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#ifdef CONFIG_X86_64
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.extra_user_64bit_cs = __USER_CS,
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#endif
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};
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struct pv_init_ops pv_init_ops = {
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.patch = native_patch,
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};
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struct pv_time_ops pv_time_ops = {
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.sched_clock = native_sched_clock,
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.steal_clock = native_steal_clock,
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};
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__visible struct pv_irq_ops pv_irq_ops = {
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.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
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.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
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.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
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.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
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.safe_halt = native_safe_halt,
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.halt = native_halt,
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#ifdef CONFIG_X86_64
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.adjust_exception_frame = paravirt_nop,
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#endif
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};
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__visible struct pv_cpu_ops pv_cpu_ops = {
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.cpuid = native_cpuid,
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.get_debugreg = native_get_debugreg,
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.set_debugreg = native_set_debugreg,
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.clts = native_clts,
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.read_cr0 = native_read_cr0,
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.write_cr0 = native_write_cr0,
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.read_cr4 = native_read_cr4,
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.write_cr4 = native_write_cr4,
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#ifdef CONFIG_X86_64
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.read_cr8 = native_read_cr8,
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.write_cr8 = native_write_cr8,
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#endif
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.wbinvd = native_wbinvd,
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.read_msr = native_read_msr,
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.write_msr = native_write_msr,
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.read_msr_safe = native_read_msr_safe,
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.write_msr_safe = native_write_msr_safe,
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.read_pmc = native_read_pmc,
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.load_tr_desc = native_load_tr_desc,
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.set_ldt = native_set_ldt,
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.load_gdt = native_load_gdt,
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.load_idt = native_load_idt,
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.store_idt = native_store_idt,
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.store_tr = native_store_tr,
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.load_tls = native_load_tls,
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#ifdef CONFIG_X86_64
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.load_gs_index = native_load_gs_index,
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#endif
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.write_ldt_entry = native_write_ldt_entry,
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.write_gdt_entry = native_write_gdt_entry,
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.write_idt_entry = native_write_idt_entry,
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.alloc_ldt = paravirt_nop,
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.free_ldt = paravirt_nop,
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.load_sp0 = native_load_sp0,
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#ifdef CONFIG_X86_64
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.usergs_sysret64 = native_usergs_sysret64,
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#endif
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.iret = native_iret,
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.swapgs = native_swapgs,
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.set_iopl_mask = native_set_iopl_mask,
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.io_delay = native_io_delay,
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.start_context_switch = paravirt_nop,
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.end_context_switch = paravirt_nop,
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};
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/* At this point, native_get/set_debugreg has real function entries */
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NOKPROBE_SYMBOL(native_get_debugreg);
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NOKPROBE_SYMBOL(native_set_debugreg);
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NOKPROBE_SYMBOL(native_load_idt);
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#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
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/* 32-bit pagetable entries */
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#define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
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#else
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/* 64-bit pagetable entries */
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#define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
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#endif
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struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
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.read_cr2 = native_read_cr2,
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.write_cr2 = native_write_cr2,
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.read_cr3 = native_read_cr3,
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.write_cr3 = native_write_cr3,
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.flush_tlb_user = native_flush_tlb,
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.flush_tlb_kernel = native_flush_tlb_global,
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.flush_tlb_single = native_flush_tlb_single,
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.flush_tlb_others = native_flush_tlb_others,
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.pgd_alloc = __paravirt_pgd_alloc,
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.pgd_free = paravirt_nop,
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.alloc_pte = paravirt_nop,
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.alloc_pmd = paravirt_nop,
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.alloc_pud = paravirt_nop,
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.release_pte = paravirt_nop,
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.release_pmd = paravirt_nop,
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.release_pud = paravirt_nop,
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.set_pte = native_set_pte,
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.set_pte_at = native_set_pte_at,
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.set_pmd = native_set_pmd,
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.set_pmd_at = native_set_pmd_at,
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.pte_update = paravirt_nop,
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.ptep_modify_prot_start = __ptep_modify_prot_start,
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.ptep_modify_prot_commit = __ptep_modify_prot_commit,
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#if CONFIG_PGTABLE_LEVELS >= 3
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#ifdef CONFIG_X86_PAE
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.set_pte_atomic = native_set_pte_atomic,
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.pte_clear = native_pte_clear,
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.pmd_clear = native_pmd_clear,
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#endif
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.set_pud = native_set_pud,
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.pmd_val = PTE_IDENT,
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.make_pmd = PTE_IDENT,
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#if CONFIG_PGTABLE_LEVELS == 4
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.pud_val = PTE_IDENT,
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.make_pud = PTE_IDENT,
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.set_pgd = native_set_pgd,
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#endif
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#endif /* CONFIG_PGTABLE_LEVELS >= 3 */
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.pte_val = PTE_IDENT,
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.pgd_val = PTE_IDENT,
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.make_pte = PTE_IDENT,
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.make_pgd = PTE_IDENT,
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.dup_mmap = paravirt_nop,
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.exit_mmap = paravirt_nop,
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.activate_mm = paravirt_nop,
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.lazy_mode = {
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.enter = paravirt_nop,
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.leave = paravirt_nop,
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.flush = paravirt_nop,
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},
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.set_fixmap = native_set_fixmap,
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};
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EXPORT_SYMBOL_GPL(pv_time_ops);
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EXPORT_SYMBOL (pv_cpu_ops);
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EXPORT_SYMBOL (pv_mmu_ops);
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EXPORT_SYMBOL_GPL(pv_info);
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EXPORT_SYMBOL (pv_irq_ops);
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