linux-stable.git/arch/x86/entry, branch linux-4.8.y

ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it

2017-01-09T07:21:57+00:00

commit 847fa1a6d3d00f3bdf68ef5fa4a786f644a0dd67 upstream.

With new binutils, gcc may get smart with its optimization and change a jmp
from a 5 byte jump to a 2 byte one even though it was jumping to a global
function. But that global function existed within a 2 byte radius, and gcc
was able to optimize it. Unfortunately, that jump was also being modified
when function graph tracing begins. Since ftrace expected that jump to be 5
bytes, but it was only two, it overwrote code after the jump, causing a
crash.

This was fixed for x86_64 with commit 8329e818f149, with the same subject as
this commit, but nothing was done for x86_32.

Fixes: d61f82d06672 ("ftrace: use dynamic patching for updating mcount calls")
Reported-by: Colin Ian King 
Tested-by: Colin Ian King 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

x86/build: Fix build with older GCC versions

2016-11-18T09:51:50+00:00

commit a2209b742e6cf978b85d4f31a25a269c3d3b062b upstream.

Older GCC (observed with 4.1.x) doesn't support -Wno-override-init and
also doesn't ignore unknown -Wno-* options.

Signed-off-by: Jan Beulich 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Valdis Kletnieks 
Cc: Valdis.Kletnieks@vt.edu
Fixes: 5e44258d16 "x86/build: Reduce the W=1 warnings noise when compiling x86 syscall tables"
Link: http://lkml.kernel.org/r/580E3E1C02000078001191C4@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86/entry/64: Fix context tracking state warning when load_gs_index fails

2016-09-30T11:53:12+00:00

This warning:

 WARNING: CPU: 0 PID: 3331 at arch/x86/entry/common.c:45 enter_from_user_mode+0x32/0x50
 CPU: 0 PID: 3331 Comm: ldt_gdt_64 Not tainted 4.8.0-rc7+ #13
 Call Trace:
  dump_stack+0x99/0xd0
  __warn+0xd1/0xf0
  warn_slowpath_null+0x1d/0x20
  enter_from_user_mode+0x32/0x50
  error_entry+0x6d/0xc0
  ? general_protection+0x12/0x30
  ? native_load_gs_index+0xd/0x20
  ? do_set_thread_area+0x19c/0x1f0
  SyS_set_thread_area+0x24/0x30
  do_int80_syscall_32+0x7c/0x220
  entry_INT80_compat+0x38/0x50

... can be reproduced by running the GS testcase of the ldt_gdt test unit in
the x86 selftests.

do_int80_syscall_32() will call enter_form_user_mode() to convert context
tracking state from user state to kernel state. The load_gs_index() call
can fail with user gsbase, gsbase will be fixed up and proceed if this
happen.

However, enter_from_user_mode() will be called again in the fixed up path
though it is context tracking kernel state currently.

This patch fixes it by just fixing up gsbase and telling lockdep that IRQs
are off once load_gs_index() failed with user gsbase.

Signed-off-by: Wanpeng Li 
Acked-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1475197266-3440-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar

x86/vdso: Fix building on big endian host

2016-09-30T10:37:40+00:00

We need to call GET_LE to read hdr->e_type.

Fixes: 57f90c3dfc75 ("x86/vdso: Error out if the vDSO isn't a valid DSO")
Reported-by: Paul Gortmaker 
Signed-off-by: Segher Boessenkool 
Acked-by: Andy Lutomirski 
Cc: Stephen Rothwell 
Cc: linux-next@vger.kernel.org
Link: http://lkml.kernel.org/r/20160929193442.GA16617@gate.crashing.org
Signed-off-by: Thomas Gleixner

x86/build: Reduce the W=1 warnings noise when compiling x86 syscall tables

2016-08-10T14:05:16+00:00

Building an X86_64 kernel with W=1 throws a total of 9,948 lines of warnings of
this form for both 32-bit and 64-bit syscall tables. Given that the entire rest
of the build for my config only generates 8,375 lines of output, this is a big
reduction in the warnings generated.

The warnings follow this pattern:

  ./arch/x86/include/generated/asm/syscalls_32.h:885:21: warning: initialized field overwritten [-Woverride-init]
   __SYSCALL_I386(379, compat_sys_pwritev2, )
                     ^
  arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
   #define __SYSCALL_I386(nr, sym, qual) [nr] = sym,
                                              ^~~
  ./arch/x86/include/generated/asm/syscalls_32.h:885:21: note: (near initialization for 'ia32_sys_call_table[379]')
   __SYSCALL_I386(379, compat_sys_pwritev2, )
                     ^
  arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
   #define __SYSCALL_I386(nr, sym, qual) [nr] = sym,

Since we intentionally build the syscall tables this way, ignore that one
warning in the two files.

Signed-off-by: Valdis Kletnieks 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/7464.1470021890@turing-police.cc.vt.edu
Signed-off-by: Ingo Molnar

x86/entry: Clarify the RF saving/restoring situation with SYSCALL/SYSRET

2016-08-10T13:53:43+00:00

Clarify why exactly RF cannot be restored properly by SYSRET to avoid
confusion.

No functionality change.

Signed-off-by: Borislav Petkov 
Acked-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20160803171429.GA2590@nazgul.tnic
Signed-off-by: Ingo Molnar

x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.text

2016-08-10T12:19:33+00:00

Dmitry Vyukov has reported unexpected KASAN stackdepot growth:

  https://github.com/google/kasan/issues/36

... which is caused by the APIC handlers not being present in .irqentry.text:

When building with CONFIG_FUNCTION_GRAPH_TRACER=y or CONFIG_KASAN=y, put the
APIC interrupt handlers into the .irqentry.text section. This is needed
because both KASAN and function graph tracer use __irqentry_text_start and
__irqentry_text_end to determine whether a function is an IRQ entry point.

Reported-by: Dmitry Vyukov 
Signed-off-by: Alexander Potapenko 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: aryabinin@virtuozzo.com
Cc: kasan-dev@googlegroups.com
Cc: kcc@google.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1468575763-144889-1-git-send-email-glider@google.com
[ Minor edits. ]
Signed-off-by: Ingo Molnar

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2016-08-06T13:18:21+00:00

Pull more KVM updates from Paolo Bonzini:
 - ARM bugfix and MSI injection support
 - x86 nested virt tweak and OOPS fix
 - Simplify pvclock code (vdso bits acked by Andy Lutomirski).

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  nvmx: mark ept single context invalidation as supported
  nvmx: remove comment about missing nested vpid support
  KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off
  KVM: documentation: fix KVM_CAP_X2APIC_API information
  x86: vdso: use __pvclock_read_cycles
  pvclock: introduce seqcount-like API
  arm64: KVM: Set cpsr before spsr on fault injection
  KVM: arm: vgic-irqfd: Workaround changing kvm_set_routing_entry prototype
  KVM: arm/arm64: Enable MSI routing
  KVM: arm/arm64: Enable irqchip routing
  KVM: Move kvm_setup_default/empty_irq_routing declaration in arch specific header
  KVM: irqchip: Convey devid to kvm_set_msi
  KVM: Add devid in kvm_kernel_irq_routing_entry
  KVM: api: Pass the devid in the msi routing entry

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-08-06T13:04:35+00:00

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

x86: vdso: use __pvclock_read_cycles

2016-08-04T11:52:21+00:00

The new simplified __pvclock_read_cycles does the same computation
as vread_pvclock, except that (because it takes the pvclock_vcpu_time_info
pointer) it has to be moved inside the loop.  Since the loop is expected to
never roll, this makes no difference.

Acked-by: Andy Lutomirski 
Signed-off-by: Paolo Bonzini