1. 23 7月, 2015 1 次提交
  2. 09 6月, 2015 3 次提交
  3. 08 6月, 2015 2 次提交
    • I
      x86/asm/entry: Untangle 'system_call' into two entry points: entry_SYSCALL_64 and entry_INT80_32 · b2502b41
      Ingo Molnar 提交于
      The 'system_call' entry points differ starkly between native 32-bit and 64-bit
      kernels: on 32-bit kernels it defines the INT 0x80 entry point, while on
      64-bit it's the SYSCALL entry point.
      
      This is pretty confusing when looking at generic code, and it also obscures
      the nature of the entry point at the assembly level.
      
      So unangle this by splitting the name into its two uses:
      
      	system_call (32) -> entry_INT80_32
      	system_call (64) -> entry_SYSCALL_64
      
      As per the generic naming scheme for x86 system call entry points:
      
      	entry_MNEMONIC_qualifier
      
      where 'qualifier' is one of _32, _64 or _compat.
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      b2502b41
    • I
      x86/asm/entry: Rename compat syscall entry points · 2cd23553
      Ingo Molnar 提交于
      Rename the following system call entry points:
      
      	ia32_cstar_target       -> entry_SYSCALL_compat
      	ia32_syscall            -> entry_INT80_compat
      
      The generic naming scheme for x86 system call entry points is:
      
      	entry_MNEMONIC_qualifier
      
      where 'qualifier' is one of _32, _64 or _compat.
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      2cd23553
  4. 19 5月, 2015 13 次提交
    • I
      x86/fpu: Pass 'struct fpu' to fpu__restore() · e1884d69
      Ingo Molnar 提交于
      This cleans up the call sites and the function a bit,
      and also makes it more symmetric with the other high
      level FPU state handling functions.
      
      It's still only valid for the current task, as we copy
      to the FPU registers of the current CPU.
      
      No change in functionality.
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      e1884d69
    • I
      x86/fpu: Harmonize FPU register state types · c47ada30
      Ingo Molnar 提交于
      Use these consistent names:
      
          struct fregs_state           # was: i387_fsave_struct
          struct fxregs_state          # was: i387_fxsave_struct
          struct swregs_state          # was: i387_soft_struct
          struct xregs_state           # was: xsave_struct
          union  fpregs_state          # was: thread_xstate
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      c47ada30
    • I
      x86/fpu: Factor out the exception error code handling code · e1cebad4
      Ingo Molnar 提交于
      Factor out the FPU error code handling code from traps.c and fpu/internal.h
      and move them close to each other.
      
      Also convert the helper functions to 'struct fpu *', which further simplifies
      them.
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      e1cebad4
    • I
      x86/fpu: Simplify FPU handling by embedding the fpstate in task_struct (again) · 7366ed77
      Ingo Molnar 提交于
      So 6 years ago we made the FPU fpstate dynamically allocated:
      
        aa283f49 ("x86, fpu: lazy allocation of FPU area - v5")
        61c4628b ("x86, fpu: split FPU state from task struct - v5")
      
      In hindsight this was a mistake:
      
         - it complicated context allocation failure handling, such as:
      
      		/* kthread execs. TODO: cleanup this horror. */
      		if (WARN_ON(fpstate_alloc_init(fpu)))
      			force_sig(SIGKILL, tsk);
      
         - it caused us to enable irqs in fpu__restore():
      
                      local_irq_enable();
                      /*
                       * does a slab alloc which can sleep
                       */
                      if (fpstate_alloc_init(fpu)) {
                              /*
                               * ran out of memory!
                               */
                              do_group_exit(SIGKILL);
                              return;
                      }
                      local_irq_disable();
      
         - it (slightly) slowed down task creation/destruction by adding
           slab allocation/free pattens.
      
         - it made access to context contents (slightly) slower by adding
           one more pointer dereference.
      
      The motivation for the dynamic allocation was two-fold:
      
         - reduce memory consumption by non-FPU tasks
      
         - allocate and handle only the necessary amount of context for
           various XSAVE processors that have varying hardware frame
           sizes.
      
      These days, with glibc using SSE memcpy by default and GCC optimizing
      for SSE/AVX by default, the scope of FPU using apps on an x86 system is
      much larger than it was 6 years ago.
      
      For example on a freshly installed Fedora 21 desktop system, with a
      recent kernel, all non-kthread tasks have used the FPU shortly after
      bootup.
      
      Also, even modern embedded x86 CPUs try to support the latest vector
      instruction set - so they'll too often use the larger xstate frame
      sizes.
      
      So remove the dynamic allocation complication by embedding the FPU
      fpstate in task_struct again. This should make the FPU a lot more
      accessible to all sorts of atomic contexts.
      
      We could still optimize for the xstate frame size in the future,
      by moving the state structure to the last element of task_struct,
      and allocating only a part of that.
      
      This change is kept minimal by still keeping the ctx_alloc()/free()
      routines (that now do nothing substantial) - we'll remove them in
      the following patches.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      7366ed77
    • I
      x86/fpu: Rename fpu_save_init() to copy_fpregs_to_fpstate() · 4f836347
      Ingo Molnar 提交于
      So fpu_save_init() is a historic name that got its name when the only
      way the FPU state was FNSAVE, which cleared (well, destroyed) the FPU
      state after saving it.
      
      Nowadays the name is misleading, because ever since the introduction of
      FXSAVE (and more modern FPU saving instructions) the 'we need to reload
      the FPU state' part is only true if there's a pending FPU exception [*],
      which is almost never the case.
      
      So rename it to copy_fpregs_to_fpstate() to make it clear what's
      happening. Also add a few comments about why we cannot keep registers
      in certain cases.
      
      Also clean up the control flow a bit, to make it more apparent when
      we are dropping/keeping FP registers, and to optimize the common
      case (of keeping fpregs) some more.
      
      [*] Probably not true anymore, modern instructions always leave the FPU
          state intact, even if exceptions are pending: because pending FP
          exceptions are posted on the next FP instruction, not asynchronously.
      
          They were truly asynchronous back in the IRQ13 case, and we had to
          synchronize with them, but that code is not working anymore: we don't
          have IRQ13 mapped in the IDT anymore.
      
          But a cleanup patch is obviously not the place to change subtle behavior.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      4f836347
    • I
      x86/fpu: Rename fpu-internal.h to fpu/internal.h · 78f7f1e5
      Ingo Molnar 提交于
      This unifies all the FPU related header files under a unified, hiearchical
      naming scheme:
      
       - asm/fpu/types.h:      FPU related data types, needed for 'struct task_struct',
                               widely included in almost all kernel code, and hence kept
                               as small as possible.
      
       - asm/fpu/api.h:        FPU related 'public' methods exported to other subsystems.
      
       - asm/fpu/internal.h:   FPU subsystem internal methods
      
       - asm/fpu/xsave.h:      XSAVE support internal methods
      
      (Also standardize the header guard in asm/fpu/internal.h.)
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      78f7f1e5
    • I
      x86/fpu: Use 'struct fpu' in fpu__save() · 0c070595
      Ingo Molnar 提交于
      Migrate this function to pure 'struct fpu' usage.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0c070595
    • I
      x86/fpu: Rename math_state_restore() to fpu__restore() · 3a0aee48
      Ingo Molnar 提交于
      Move to the new fpu__*() namespace.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3a0aee48
    • I
      x86/fpu: Move math_state_restore() to fpu/core.c · 93b90712
      Ingo Molnar 提交于
      It's another piece of FPU internals that is better off close to
      the other FPU internals.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      93b90712
    • I
      x86/fpu: Fix header file dependencies of fpu-internal.h · f89e32e0
      Ingo Molnar 提交于
      Fix a minor header file dependency bug in asm/fpu-internal.h: it
      relies on i387.h but does not include it. All users of fpu-internal.h
      included it explicitly.
      
      Also remove unnecessary includes, to reduce compilation time.
      
      This also makes it easier to use it as a standalone header file
      for FPU internals, such as an upcoming C module in arch/x86/kernel/fpu/.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      f89e32e0
    • I
      x86/fpu: Move thread_info::fpu_counter into thread_info::fpu.counter · c0c2803d
      Ingo Molnar 提交于
      This field is kept separate from the main FPU state structure for
      no good reason.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      c0c2803d
    • I
      x86/fpu: Split an fpstate_alloc_init() function out of init_fpu() · 97185c95
      Ingo Molnar 提交于
      Most init_fpu() users don't want the register-saving aspect of the
      function, they are calling it for 'current' and when FPU registers
      are not allocated and initialized yet.
      
      Split out a simplified API that does just that (and add debug-checks
      for these conditions): fpstate_alloc_init().
      
      Use it where appropriate.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      97185c95
    • I
      x86/fpu: Rename unlazy_fpu() to fpu__save() · 0a781551
      Ingo Molnar 提交于
      This function is a misnomer on two levels:
      
      1) it doesn't really manipulate TS on modern CPUs anymore, its
         primary purpose is to save FPU state, used:
      
            - when executing fork()/clone(): to copy current FPU state
              to the child's FPU state.
      
            - when handling math exceptions: to generate the math error
              si_code in the signal frame.
      
      2) even on legacy CPUs it doesn't actually 'unlazy', if then
         it lazies the FPU state: as a side effect of the old FNSAVE
         instruction which clears (destroys) FPU state it's necessary
         to set CR0::TS.
      
      So rename it to fpu__save() to better reflect its purpose.
      Reviewed-by: NBorislav Petkov <bp@alien8.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0a781551
  5. 10 5月, 2015 1 次提交
  6. 07 5月, 2015 2 次提交
  7. 31 3月, 2015 1 次提交
    • I
      x86/asm/entry: Remove user_mode_ignore_vm86() · 55474c48
      Ingo Molnar 提交于
      user_mode_ignore_vm86() can be used instead of user_mode(), in
      places where we have already done a v8086_mode() security
      check of ptregs.
      
      But doing this check in the wrong place would be a bug that
      could result in security problems, and also the naming still
      isn't very clear.
      
      Furthermore, it only affects 32-bit kernels, while most
      development happens on 64-bit kernels.
      
      If we replace them with user_mode() checks then the cost is only
      a very minor increase in various slowpaths:
      
         text             data   bss     dec              hex    filename
         10573391         703562 1753042 13029995         c6d26b vmlinux.o.before
         10573423         703562 1753042 13030027         c6d28b vmlinux.o.after
      
      So lets get rid of this distinction once and for all.
      Acked-by: NBorislav Petkov <bp@suse.de>
      Acked-by: NAndy Lutomirski <luto@kernel.org>
      Cc: Andrew Lutomirski <luto@kernel.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brad Spengler <spender@grsecurity.net>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/20150329090233.GA1963@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      55474c48
  8. 23 3月, 2015 4 次提交
  9. 10 3月, 2015 1 次提交
  10. 09 3月, 2015 1 次提交
    • F
      context_tracking: Rename context symbols to prepare for transition state · c467ea76
      Frederic Weisbecker 提交于
      Current context tracking symbols are designed to express living state.
      As such they are prefixed with "IN_": IN_USER, IN_KERNEL.
      
      Now we are going to use these symbols to also express state transitions
      such as context_tracking_enter(IN_USER) or context_tracking_exit(IN_USER).
      But while the "IN_" prefix works well to express entering a context, it's
      confusing to depict a context exit: context_tracking_exit(IN_USER)
      could mean two things:
      	1) We are exiting the current context to enter user context.
      	2) We are exiting the user context
      We want 2) but the reviewer may be confused and understand 1)
      
      So lets disambiguate these symbols and rename them to CONTEXT_USER and
      CONTEXT_KERNEL.
      Acked-by: NRik van Riel <riel@redhat.com>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Will deacon <will.deacon@arm.com>
      Cc: Marcelo Tosatti <mtosatti@redhat.com>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      Cc: Luiz Capitulino <lcapitulino@redhat.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      c467ea76
  11. 07 3月, 2015 1 次提交
  12. 06 3月, 2015 1 次提交
  13. 05 3月, 2015 1 次提交
  14. 26 2月, 2015 1 次提交
  15. 19 2月, 2015 1 次提交
  16. 01 2月, 2015 1 次提交
  17. 20 1月, 2015 1 次提交
  18. 03 1月, 2015 3 次提交
    • A
      x86, traps: Add ist_begin_non_atomic and ist_end_non_atomic · bced35b6
      Andy Lutomirski 提交于
      In some IST handlers, if the interrupt came from user mode,
      we can safely enable preemption.  Add helpers to do it safely.
      
      This is intended to be used my the memory failure code in
      do_machine_check.
      Acked-by: NBorislav Petkov <bp@suse.de>
      Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
      bced35b6
    • A
      x86, traps: Track entry into and exit from IST context · 95927475
      Andy Lutomirski 提交于
      We currently pretend that IST context is like standard exception
      context, but this is incorrect.  IST entries from userspace are like
      standard exceptions except that they use per-cpu stacks, so they are
      atomic.  IST entries from kernel space are like NMIs from RCU's
      perspective -- they are not quiescent states even if they
      interrupted the kernel during a quiescent state.
      
      Add and use ist_enter and ist_exit to track IST context.  Even
      though x86_32 has no IST stacks, we track these interrupts the same
      way.
      
      This fixes two issues:
      
       - Scheduling from an IST interrupt handler will now warn.  It would
         previously appear to work as long as we got lucky and nothing
         overwrote the stack frame.  (I don't know of any bugs in this
         that would trigger the warning, but it's good to be on the safe
         side.)
      
       - RCU handling in IST context was dangerous.  As far as I know,
         only machine checks were likely to trigger this, but it's good to
         be on the safe side.
      
      Note that the machine check handlers appears to have been missing
      any context tracking at all before this patch.
      
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Frédéric Weisbecker <fweisbec@gmail.com>
      Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
      95927475
    • A
      x86, entry: Switch stacks on a paranoid entry from userspace · 48e08d0f
      Andy Lutomirski 提交于
      This causes all non-NMI, non-double-fault kernel entries from
      userspace to run on the normal kernel stack.  Double-fault is
      exempt to minimize confusion if we double-fault directly from
      userspace due to a bad kernel stack.
      
      This is, suprisingly, simpler and shorter than the current code.  It
      removes the IMO rather frightening paranoid_userspace path, and it
      make sync_regs much simpler.
      
      There is no risk of stack overflow due to this change -- the kernel
      stack that we switch to is empty.
      
      This will also enable us to create non-atomic sections within
      machine checks from userspace, which will simplify memory failure
      handling.  It will also allow the upcoming fsgsbase code to be
      simplified, because it doesn't need to worry about usergs when
      scheduling in paranoid_exit, as that code no longer exists.
      
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Tony Luck <tony.luck@intel.com>
      Acked-by: NBorislav Petkov <bp@alien8.de>
      Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
      48e08d0f
  19. 08 12月, 2014 1 次提交