linux-stable.git/arch, branch v4.4.185

KVM: x86: degrade WARN to pr_warn_ratelimited

2019-07-10T07:56:44+00:00

commit 3f16a5c318392cbb5a0c7a3d19dff8c8ef3c38ee upstream.

This warning can be triggered easily by userspace, so it should certainly not
cause a panic if panic_on_warn is set.

Reported-by: syzbot+c03f30b4f4c46bdf8575@syzkaller.appspotmail.com
Suggested-by: Alexander Potapenko 
Acked-by: Alexander Potapenko 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

arm64, vdso: Define vdso_{start,end} as array

2019-07-10T07:56:44+00:00

Commit dbbb08f500d6146398b794fdc68a8e811366b451 upstream.

Adjust vdso_{start|end} to be char arrays to avoid compile-time analysis
that flags "too large" memcmp() calls with CONFIG_FORTIFY_SOURCE.

Cc: Jisheng Zhang 
Acked-by: Catalin Marinas 
Suggested-by: Mark Rutland 
Signed-off-by: Kees Cook 
Signed-off-by: Will Deacon 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Sasha Levin

ARC: handle gcc generated __builtin_trap for older compiler

2019-07-10T07:56:44+00:00

commit af1be2e21203867cb958aaceed5366e2e24b88e8 upstream.

ARC gcc prior to GNU 2018.03 release didn't have a target specific
__builtin_trap() implementation, generating default abort() call.

Implement the abort() call - emulating what newer gcc does for the same,
as suggested by Arnd.

Acked-by: Arnd Bergmann 
Signed-off-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman

MIPS: Workaround GCC __builtin_unreachable reordering bug

2019-07-10T07:56:42+00:00

[ Upstream commit 906d441febc0de974b2a6ef848a8f058f3bfada3 ]

Some versions of GCC for the MIPS architecture suffer from a bug which
can lead to instructions from beyond an unreachable statement being
incorrectly reordered into earlier branch delay slots if the unreachable
statement is the only content of a case in a switch statement. This can
lead to seemingly random behaviour, such as invalid memory accesses from
incorrectly reordered loads or stores, and link failures on microMIPS
builds.

See this potential GCC fix for details:

    https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00360.html

Runtime problems resulting from this bug were initially observed using a
maltasmvp_defconfig v4.4 kernel built using GCC 4.9.2 (from a Codescape
SDK 2015.06-05 toolchain), with the result being an address exception
taken after log messages about the L1 caches (during probe of the L2
cache):

    Initmem setup node 0 [mem 0x0000000080000000-0x000000009fffffff]
    VPE topology {2,2} total 4
    Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
    Primary data cache 64kB, 4-way, PIPT, no aliases, linesize 32 bytes
    

This is early enough that the kernel exception vectors are not in use,
so any further output depends upon the bootloader. This is reproducible
in QEMU where no further output occurs - ie. the system hangs here.
Given the nature of the bug it may potentially be hit with differing
symptoms. The bug is known to affect GCC versions as recent as 7.3, and
it is unclear whether GCC 8 fixed it or just happens not to encounter
the bug in the testcase found at the link above due to differing
optimizations.

This bug can be worked around by placing a volatile asm statement, which
GCC is prevented from reordering past, prior to the
__builtin_unreachable call.

That was actually done already for other reasons by commit 173a3efd3edb
("bug.h: work around GCC PR82365 in BUG()"), but creates problems for
microMIPS builds due to the lack of a .insn directive. The microMIPS ISA
allows for interlinking with regular MIPS32 code by repurposing bit 0 of
the program counter as an ISA mode bit. To switch modes one changes the
value of this bit in the PC. However typical branch instructions encode
their offsets as multiples of 2-byte instruction halfwords, which means
they cannot change ISA mode - this must be done using either an indirect
branch (a jump-register in MIPS terminology) or a dedicated jalx
instruction. In order to ensure that regular branches don't attempt to
target code in a different ISA which they can't actually switch to, the
linker will check that branch targets are code in the same ISA as the
branch.

Unfortunately our empty asm volatile statements don't qualify as code,
and the link for microMIPS builds fails with errors such as:

    arch/mips/mm/dma-default.s:3265: Error: branch to a symbol in another ISA mode
    arch/mips/mm/dma-default.s:5027: Error: branch to a symbol in another ISA mode

Resolve this by adding a .insn directive within the asm statement which
declares that what comes next is code. This may or may not be true,
since we don't really know what comes next, but as this code is in an
unreachable path anyway that doesn't matter since we won't execute it.

We do this in asm/compiler.h & select CONFIG_HAVE_ARCH_COMPILER_H in
order to have this included by linux/compiler_types.h after
linux/compiler-gcc.h. This will result in asm/compiler.h being included
in all C compilations via the -include linux/compiler_types.h argument
in c_flags, which should be harmless.

Signed-off-by: Paul Burton 
Fixes: 173a3efd3edb ("bug.h: work around GCC PR82365 in BUG()")
Patchwork: https://patchwork.linux-mips.org/patch/20270/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: Arnd Bergmann 
Cc: linux-mips@linux-mips.org
Signed-off-by: Sasha Levin

bug.h: work around GCC PR82365 in BUG()

2019-07-10T07:56:42+00:00

[ Upstream commit 173a3efd3edb2ef6ef07471397c5f542a360e9c1 ]

Looking at functions with large stack frames across all architectures
led me discovering that BUG() suffers from the same problem as
fortify_panic(), which I've added a workaround for already.

In short, variables that go out of scope by calling a noreturn function
or __builtin_unreachable() keep using stack space in functions
afterwards.

A workaround that was identified is to insert an empty assembler
statement just before calling the function that doesn't return.  I'm
adding a macro "barrier_before_unreachable()" to document this, and
insert calls to that in all instances of BUG() that currently suffer
from this problem.

The files that saw the largest change from this had these frame sizes
before, and much less with my patch:

  fs/ext4/inode.c:82:1: warning: the frame size of 1672 bytes is larger than 800 bytes [-Wframe-larger-than=]
  fs/ext4/namei.c:434:1: warning: the frame size of 904 bytes is larger than 800 bytes [-Wframe-larger-than=]
  fs/ext4/super.c:2279:1: warning: the frame size of 1160 bytes is larger than 800 bytes [-Wframe-larger-than=]
  fs/ext4/xattr.c:146:1: warning: the frame size of 1168 bytes is larger than 800 bytes [-Wframe-larger-than=]
  fs/f2fs/inode.c:152:1: warning: the frame size of 1424 bytes is larger than 800 bytes [-Wframe-larger-than=]
  net/netfilter/ipvs/ip_vs_core.c:1195:1: warning: the frame size of 1068 bytes is larger than 800 bytes [-Wframe-larger-than=]
  net/netfilter/ipvs/ip_vs_core.c:395:1: warning: the frame size of 1084 bytes is larger than 800 bytes [-Wframe-larger-than=]
  net/netfilter/ipvs/ip_vs_ftp.c:298:1: warning: the frame size of 928 bytes is larger than 800 bytes [-Wframe-larger-than=]
  net/netfilter/ipvs/ip_vs_ftp.c:418:1: warning: the frame size of 908 bytes is larger than 800 bytes [-Wframe-larger-than=]
  net/netfilter/ipvs/ip_vs_lblcr.c:718:1: warning: the frame size of 960 bytes is larger than 800 bytes [-Wframe-larger-than=]
  drivers/net/xen-netback/netback.c:1500:1: warning: the frame size of 1088 bytes is larger than 800 bytes [-Wframe-larger-than=]

In case of ARC and CRIS, it turns out that the BUG() implementation
actually does return (or at least the compiler thinks it does),
resulting in lots of warnings about uninitialized variable use and
leaving noreturn functions, such as:

  block/cfq-iosched.c: In function 'cfq_async_queue_prio':
  block/cfq-iosched.c:3804:1: error: control reaches end of non-void function [-Werror=return-type]
  include/linux/dmaengine.h: In function 'dma_maxpq':
  include/linux/dmaengine.h:1123:1: error: control reaches end of non-void function [-Werror=return-type]

This makes them call __builtin_trap() instead, which should normally
dump the stack and kill the current process, like some of the other
architectures already do.

I tried adding barrier_before_unreachable() to panic() and
fortify_panic() as well, but that had very little effect, so I'm not
submitting that patch.

Vineet said:

: For ARC, it is double win.
:
: 1. Fixes 3 -Wreturn-type warnings
:
: | ../net/core/ethtool.c:311:1: warning: control reaches end of non-void function
: [-Wreturn-type]
: | ../kernel/sched/core.c:3246:1: warning: control reaches end of non-void function
: [-Wreturn-type]
: | ../include/linux/sunrpc/svc_xprt.h:180:1: warning: control reaches end of
: non-void function [-Wreturn-type]
:
: 2.  bloat-o-meter reports code size improvements as gcc elides the
:    generated code for stack return.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
Link: http://lkml.kernel.org/r/20171219114112.939391-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann 
Acked-by: Vineet Gupta 	[arch/arc]
Tested-by: Vineet Gupta 	[arch/arc]
Cc: Mikael Starvik 
Cc: Jesper Nilsson 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Geert Uytterhoeven 
Cc: "David S. Miller" 
Cc: Christopher Li 
Cc: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Kees Cook 
Cc: Ingo Molnar 
Cc: Josh Poimboeuf 
Cc: Will Deacon 
Cc: "Steven Rostedt (VMware)" 
Cc: Mark Rutland 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin 
[ removed cris changes - gregkh]
Signed-off-by: Greg Kroah-Hartman

MIPS: math-emu: do not use bools for arithmetic

2019-07-10T07:56:41+00:00

[ Upstream commit 8535f2ba0a9b971df62a5890699b9dfe2e0d5580 ]

GCC-7 complains about a boolean value being used with an arithmetic
AND:

arch/mips/math-emu/cp1emu.c: In function 'cop1Emulate':
arch/mips/math-emu/cp1emu.c:838:14: warning: '~' on a boolean expression [-Wbool-operation]
  fpr = (x) & ~(cop1_64bit(xcp) == 0);    \
              ^
arch/mips/math-emu/cp1emu.c:1068:3: note: in expansion of macro 'DITOREG'
   DITOREG(dval, MIPSInst_RT(ir));
   ^~~~~~~
arch/mips/math-emu/cp1emu.c:838:14: note: did you mean to use logical not?
  fpr = (x) & ~(cop1_64bit(xcp) == 0);    \

Since cop1_64bit() returns and int, just flip the LSB.

Suggested-by: Maciej W. Rozycki 
Signed-off-by: Manuel Lauss 
Reviewed-by: Maciej W. Rozycki 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17058/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin

ARC: fix build warning in elf.h

2019-07-10T07:56:41+00:00

[ Upstream commit 1dec78585328db00e33fb18dc1a6deed0e2095a5 ]

The cast valid since TASK_SIZE * 2 will never actually cause overflow.

|   CC      fs/binfmt_elf.o
| In file included from ../include/linux/elf.h:4:0,
|                  from ../include/linux/module.h:15,
|                  from ../fs/binfmt_elf.c:12:
| ../fs/binfmt_elf.c: In function load_elf_binar:
| ../arch/arc/include/asm/elf.h:57:29: warning: integer overflow in expression [-Woverflow]
|  #define ELF_ET_DYN_BASE  (2 * TASK_SIZE / 3)
|                              ^
| ../fs/binfmt_elf.c:921:16: note: in expansion of macro ELF_ET_DYN_BASE
|     load_bias = ELF_ET_DYN_BASE - vaddr;

Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: Assume multiplier is always present

2019-07-10T07:56:41+00:00

[ Upstream commit 0eca6fdb3193410fbe66b6f064431cc394513e82 ]

It is unlikely that designs running Linux will not have multiplier.
Further the current support is not complete as tool don't generate a
multilib w/o multiplier.

Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

um: Compile with modern headers

2019-07-10T07:56:39+00:00

commit 530ba6c7cb3c22435a4d26de47037bb6f86a5329 upstream.

Recent libcs have gotten a bit more strict, so we actually need to
include the right headers and use the right types. This enables UML to
compile again.

Signed-off-by: Jason A. Donenfeld 
Cc: stable@vger.kernel.org
Signed-off-by: Richard Weinberger 
Signed-off-by: Alessio Balsini 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Allow guests to use SSBD even if host does not

2019-07-10T07:56:36+00:00

commit c1f7fec1eb6a2c86d01bc22afce772c743451d88 upstream.

The bits set in x86_spec_ctrl_mask are used to calculate the guest's value
of SPEC_CTRL that is written to the MSR before VMENTRY, and control which
mitigations the guest can enable.  In the case of SSBD, unless the host has
enabled SSBD always on mode (by passing "spec_store_bypass_disable=on" in
the kernel parameters), the SSBD bit is not set in the mask and the guest
can not properly enable the SSBD always on mitigation mode.

This has been confirmed by running the SSBD PoC on a guest using the SSBD
always on mitigation mode (booted with kernel parameter
"spec_store_bypass_disable=on"), and verifying that the guest is vulnerable
unless the host is also using SSBD always on mode. In addition, the guest
OS incorrectly reports the SSB vulnerability as mitigated.

Always set the SSBD bit in x86_spec_ctrl_mask when the host CPU supports
it, allowing the guest to use SSBD whether or not the host has chosen to
enable the mitigation in any of its modes.

Fixes: be6fcb5478e9 ("x86/bugs: Rework spec_ctrl base and mask logic")
Signed-off-by: Alejandro Jimenez 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Liam Merwick 
Reviewed-by: Mark Kanda 
Reviewed-by: Paolo Bonzini 
Cc: bp@alien8.de
Cc: rkrcmar@redhat.com
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1560187210-11054-1-git-send-email-alejandro.j.jimenez@oracle.com
Signed-off-by: Greg Kroah-Hartman