| Commit message (Collapse) | Author | Age |
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It was a nice optimization while it lasted, but thread_info is moving
and this optimization will no longer work.
Quoting Linus:
Oh Gods, Andy. That pt_regs_to_thread_info() thing made me want
to do unspeakable acts on a poor innocent wax figure that looked
_exactly_ like you.
[ Changelog written by Andy. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/6376aa81c68798cc81631673f52bd91a3e078944.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Because sched.h and thread_info.h are a tangled mess, I turned
in_compat_syscall() into a macro. If we had current_thread_struct()
or similar and we could use it from thread_info.h, then this would
be a bit cleaner.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ccc8a1b2f41f9c264a41f771bb4a6539a642ad72.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
"Two fixes and a cleanup-fix, to the syscall entry code and to ptrace"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/syscalls/64: Add compat_sys_keyctl for 32-bit userspace
x86/ptrace: Stop setting TS_COMPAT in ptrace code
x86/vdso: Error out if the vDSO isn't a valid DSO
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Setting TS_COMPAT in ptrace is wrong: if we happen to do it during
syscall entry, then we'll confuse seccomp and audit. (The former
isn't a security problem: seccomp is currently entirely insecure if a
malicious ptracer is attached.) As a minimal fix, this patch adds a
new flag TS_I386_REGS_POKED that handles the ptrace special case.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5383ebed38b39fa37462139e337aff7f2314d1ca.1469599803.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
"Highlights:
- TPM core and driver updates/fixes
- IPv6 security labeling (CALIPSO)
- Lots of Apparmor fixes
- Seccomp: remove 2-phase API, close hole where ptrace can change
syscall #"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (156 commits)
apparmor: fix SECURITY_APPARMOR_HASH_DEFAULT parameter handling
tpm: Add TPM 2.0 support to the Nuvoton i2c driver (NPCT6xx family)
tpm: Factor out common startup code
tpm: use devm_add_action_or_reset
tpm2_i2c_nuvoton: add irq validity check
tpm: read burstcount from TPM_STS in one 32-bit transaction
tpm: fix byte-order for the value read by tpm2_get_tpm_pt
tpm_tis_core: convert max timeouts from msec to jiffies
apparmor: fix arg_size computation for when setprocattr is null terminated
apparmor: fix oops, validate buffer size in apparmor_setprocattr()
apparmor: do not expose kernel stack
apparmor: fix module parameters can be changed after policy is locked
apparmor: fix oops in profile_unpack() when policy_db is not present
apparmor: don't check for vmalloc_addr if kvzalloc() failed
apparmor: add missing id bounds check on dfa verification
apparmor: allow SYS_CAP_RESOURCE to be sufficient to prlimit another task
apparmor: use list_next_entry instead of list_entry_next
apparmor: fix refcount race when finding a child profile
apparmor: fix ref count leak when profile sha1 hash is read
apparmor: check that xindex is in trans_table bounds
...
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This moves seccomp after ptrace on x86 to that seccomp can catch changes
made by ptrace. Emulation should skip the rest of processing too.
We can get rid of test_thread_flag because there's no longer any
opportunity for seccomp to mess with ptrace state before invoking
ptrace.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: x86@kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
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I added two-phase syscall entry work back when the entry slow path
was very slow. Nowadays, the entry slow path is fast and two-phase
entry work serves no purpose. Remove it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
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This matches what is already done for prepare_exit_to_usermode(),
and saves about 60 clock cycles (4% speedup) with the benchmark
in the previous commit message.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/1466434712-31440-3-git-send-email-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Thanks to all the work that was done by Andy Lutomirski and others,
enter_from_user_mode() and prepare_exit_to_usermode() are now called only with
interrupts disabled. Let's provide them a version of user_enter()/user_exit()
that skips saving and restoring the interrupt flag.
On an AMD-based machine I tested this patch on, with force-enabled
context tracking, the speed-up in system calls was 90 clock cycles or 6%,
measured with the following simple benchmark:
#include <sys/signal.h>
#include <time.h>
#include <unistd.h>
#include <stdio.h>
unsigned long rdtsc()
{
unsigned long result;
asm volatile("rdtsc; shl $32, %%rdx; mov %%eax, %%eax\n"
"or %%rdx, %%rax" : "=a" (result) : : "rdx");
return result;
}
int main()
{
unsigned long tsc1, tsc2;
int pid = getpid();
int i;
tsc1 = rdtsc();
for (i = 0; i < 100000000; i++)
kill(pid, SIGWINCH);
tsc2 = rdtsc();
printf("%ld\n", tsc2 - tsc1);
}
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/1466434712-31440-2-git-send-email-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The is_ia32_task()/is_x32_task() function names are a big misnomer: they
suggests that the compat-ness of a system call is a task property, which
is not true, the compatness of a system call purely depends on how it
was invoked through the system call layer.
A task may call 32-bit and 64-bit and x32 system calls without changing
any of its kernel visible state.
This specific minomer is also actively dangerous, as it might cause kernel
developers to use the wrong kind of security checks within system calls.
So rename it to in_{ia32,x32}_syscall().
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
[ Expanded the changelog. ]
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: 0x7f454c46@gmail.com
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: akpm@linux-foundation.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1460987025-30360-1-git-send-email-dsafonov@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Now that slow-path syscalls always enter C before enabling
interrupts, it's straightforward to call enter_from_user_mode() before
enabling interrupts rather than doing it as part of entry tracing.
With this change, we should finally be able to retire exception_enter().
This will also enable optimizations based on knowing that we never
change context tracking state with interrupts on.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/bc376ecf87921a495e874ff98139b1ca2f5c5dd7.1457558566.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We want all of the syscall entries to run with interrupts off so that
we can efficiently run context tracking before enabling interrupts.
This will regress int $0x80 performance on 32-bit kernels by a
couple of cycles. This shouldn't matter much -- int $0x80 is not a
fast path.
This effectively reverts:
657c1eea0019 ("x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on")
... and fixes the same issue differently.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/59b4f90c9ebfccd8c937305dbbbca680bc74b905.1457558566.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Now that SYSENTER with TF set puts X86_EFLAGS_TF directly into
regs->flags, we don't need a TIF_SINGLESTEP fixup in the syscall
entry code. Remove it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
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: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2d15f24da52dafc9d2f0b8d76f55544f4779c517.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signal delivery needs to know the sign of an interrupted syscall's
return value in order to detect -ERESTART variants. Normally this
works independently of bitness because syscalls internally return
long. Under ptrace, however, this can break, and syscall_get_error
is supposed to sign-extend regs->ax if needed.
We were clearing TS_COMPAT too early, though, and this prevented
sign extension, which subtly broke syscall restart under ptrace.
Reported-by: Robert O'Callahan <robert@ocallahan.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
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: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # 4.3.x-
Fixes: c5c46f59e4e7 ("x86/entry: Add new, comprehensible entry and exit handlers written in C")
Link: http://lkml.kernel.org/r/cbce3cf545522f64eb37f5478cb59746230db3b5.1455142412.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Move them to a separate header and have the following
dependency:
x86/cpufeatures.h <- x86/processor.h <- x86/cpufeature.h
This makes it easier to use the header in asm code and not
include the whole cpufeature.h and add guards for asm.
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453842730-28463-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This is more complicated than the 32-bit and compat cases
because it preserves an asm fast path for the case where the
callee-saved regs aren't needed in pt_regs and no entry or exit
work needs to be done.
This appears to slow down fastpath syscalls by no more than one
cycle on my Skylake laptop.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Frederic Weisbecker <fweisbec@gmail.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>
Link: http://lkml.kernel.org/r/ce2335a4d42dc164b24132ee5e8c7716061f947b.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It turns out that some Android versions hardcode the SYSENTER
calling convention. This is buggy and will cause problems no
matter what the kernel does. Nonetheless, we should try to
support it.
Credit goes to Linus for pointing out a clean way to handle
the SYSENTER/SYSCALL clobber differences while preserving
straightforward DWARF annotations.
I believe that the original offending Android commit was:
https://android.googlesource.com/platform%2Fbionic/+/7dc3684d7a2587e43e6d2a8e0e3f39bf759bd535
Reported-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-and-tested-by: Borislav Petkov <bp@alien8.de>
Cc: <mark.gross@intel.com>
Cc: Su Tao <tao.su@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: <frank.wang@intel.com>
Cc: <borun.fu@intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Mingwei Shi <mingwei.shi@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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When I rewrote entry_INT80_32, I thought that int80 was an
interrupt gate. It's a trap gate. *facepalm*
Thanks to Brian Gerst for pointing out that it's better to
change the entry code than to change the gate type.
Suggested-by: Brian Gerst <brgerst@gmail.com>
Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
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>
Fixes: 150ac78d63af ("x86/entry/32: Switch INT80 to the new C syscall path")
Link: http://lkml.kernel.org/r/dc09d9b574a5c1dcca996847875c73f8341ce0ad.1445035014.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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GCC is unable to properly optimize functions that have a very
short likely case and a longer and register-heavier cold part --
it fails to sink all of the register saving and stack frame
setup code into the unlikely part.
Help it out with syscall_return_slowpath() by splitting it into
two parts and inline the hot part.
Saves 6 cycles for compat syscalls.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/0f773a894ab15c589ac794c2d34ca6ba9b5335c9.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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GCC is unable to properly optimize functions that have a very
short likely case and a longer and register-heavier cold part --
it fails to sink all of the register saving and stack frame
setup code into the unlikely part.
Help it out with prepare_exit_to_usermode() by splitting it into
two parts and inline the hot part.
Saves 6-8 cycles for compat syscalls.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/9fc53eda4a5b924070952f12fa4ae3e477640a07.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It generates simpler and faster code than current_thread_info().
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/a3b6633e7dcb9f673c1b619afae602d29d27d2cf.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This shaves a few cycles off the slow paths.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/ce383fa9e129286ce6da6e00b53acd4c9fb5d06a.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We're following a 32-bit pointer, and the uaccess code isn't
smart enough to figure out that the access_ok() check isn't
needed.
This saves about three cycles on a cache-hot fast syscall.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/bdff034e2f23c5eb974c760cf494cb5bddce8f29.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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On systems that support fast syscalls, we only really care about
the performance of the fast syscall path. Forcibly inline it
and add a likely annotation.
This saves 4-6 cycles.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/8472036ff1f4b426b4c4c3e3d0b3bf5264407c0c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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These checks are quite slow. Disable them in non-lockdep
kernels to reduce the performance hit.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/eccff2a154ae6fb50f40228901003a6e9c24f3d0.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This is slightly messy, but it eliminates an unnecessary cli;sti
pair.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/22f34b1096694a37326f36c53407b8dd90f37948.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/5b99659e8be70f3dd10cd8970a5c90293d9ad9a7.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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If CS, SS and IP are as expected and FLAGS is compatible with
SYSRETL, then return from fast compat syscalls (both SYSCALL and
SYSENTER) using SYSRETL.
Unlike native 64-bit opportunistic SYSRET, this is not invisible
to user code: RCX and R8-R15 end up in a different state than
shown saved in pt_regs. To compensate, we only do this when
returning to the vDSO fast syscall return path. This won't
interfere with syscall restart, as we won't use SYSRETL when
returning to the INT80 restart instruction.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/aa15e49db33773eb10b73d73466b6d5466d7856a.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This handles both SYSENTER and SYSCALL. The asm glue will take
care of the differences.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/6041a58a9b8ef6d2522ab4350deb1a1945eb563f.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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System calls are really quite simple. Add a helper to call
a 32-bit system call.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/a77ed179834c27da436fb4a7fb23c8ee77abc11c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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prepare_exit_to_usermode()
Rather than worrying about exactly where LOCKDEP_SYS_EXIT should
go in the asm code, add it to prepare_exit_from_usermode() and
remove all of the asm calls that are followed by
prepare_exit_to_usermode().
LOCKDEP_SYS_EXIT now appears only in the syscall fast paths.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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
Link: http://lkml.kernel.org/r/1736ebe948b845e68120b86b89091f3ec27f5e8e.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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They are no longer used. Good riddance!
Deleting the TIF_ macros is really nice. It was never clear why
there were so many variants.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Paris <eparis@parisplace.org>
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>
Link: http://lkml.kernel.org/r/22c61682f446628573dde0f1d573ab821677e06da.1438378274.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Linus noticed that the early return check was missing
_TIF_USER_RETURN_NOTIFY. If the only work flag was
_TIF_USER_RETURN_NOTIFY, we'd skip user return notifiers. Fix
it. (This is the only missing bit.)
This fixes double faults on a KVM host. It's the same issue as
last time, except that this time it's very easy to trigger.
Apparently no one uses -next as a KVM host.
( I'm still not quite sure what it is that KVM does that blows up
so badly if we miss a user return notifier. My best guess is that KVM
lets KERNEL_GS_BASE (i.e. the user's gs base) be negative and fixes
it up in a user return notifier. If we actually end up in user mode
with a negative gs base, we blow up pretty badly. )
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c5c46f59e4e7 ("x86/entry: Add new, comprehensible entry and exit handlers written in C")
Link: http://lkml.kernel.org/r/3f801104d24ee7a6bb1446408d9950777aa63277.1436995419.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The current x86 entry and exit code, written in a mixture of assembly and
C code, is incomprehensible due to being open-coded in a lot of places
without coherent documentation.
It appears to work primary by luck and duct tape: i.e. obvious runtime
failures were fixed on-demand, without re-thinking the design.
Due to those reasons our confidence level in that code is low, and it is
very difficult to incrementally improve.
Add new code written in C, in preparation for simply deleting the old
entry code.
prepare_exit_to_usermode() is a new function that will handle all
slow path exits to user mode. It is called with IRQs disabled
and it leaves us in a state in which it is safe to immediately
return to user mode. IRQs must not be re-enabled at any point
after prepare_exit_to_usermode() returns and user mode is actually
entered. (We can, of course, fail to enter user mode and treat
that failure as a fresh entry to kernel mode.)
All callers of do_notify_resume() will be migrated to call
prepare_exit_to_usermode() instead; prepare_exit_to_usermode() needs
to do everything that do_notify_resume() does today, but it also
takes care of scheduling and context tracking. Unlike
do_notify_resume(), it does not need to be called in a loop.
syscall_return_slowpath() is exactly what it sounds like: it will
be called on any syscall exit slow path. It will replace
syscall_trace_leave() and it calls prepare_exit_to_usermode() on the
way out.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/c57c8b87661a4152801d7d3786eac2d1a2f209dd.1435952415.git.luto@kernel.org
[ Improved the changelog a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Changing the x86 context tracking hooks is dangerous because
there are no good checks that we track our context correctly.
Add a helper to check that we're actually in CONTEXT_USER when
we enter from user mode and wire it up for syscall entries.
Subsequent patches will wire this up for all non-NMI entries as
well. NMIs are their own special beast and cannot currently
switch overall context tracking state. Instead, they have their
own special RCU hooks.
This is a tiny speedup if !CONFIG_CONTEXT_TRACKING (removes a
branch) and a tiny slowdown if CONFIG_CONTEXT_TRACING (adds a
layer of indirection). Eventually, we should fix up the core
context tracking code to supply a function that does what we
want (and can be much simpler than user_exit), which will enable
us to get rid of the extra call.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/853b42420066ec3fb856779cdc223a6dcb5d355b.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The entry and exit C helpers were confusingly scattered between
ptrace.c and signal.c, even though they aren't specific to
ptrace or signal handling. Move them together in a new file.
This change just moves code around. It doesn't change anything.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/324d686821266544d8572423cc281f961da445f4.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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