linux-stable.git/arch, branch v5.4.46

x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation

2020-06-10T18:24:57+00:00

commit 7e5b3c267d256822407a22fdce6afdf9cd13f9fb upstream

SRBDS is an MDS-like speculative side channel that can leak bits from the
random number generator (RNG) across cores and threads. New microcode
serializes the processor access during the execution of RDRAND and
RDSEED. This ensures that the shared buffer is overwritten before it is
released for reuse.

While it is present on all affected CPU models, the microcode mitigation
is not needed on models that enumerate ARCH_CAPABILITIES[MDS_NO] in the
cases where TSX is not supported or has been disabled with TSX_CTRL.

The mitigation is activated by default on affected processors and it
increases latency for RDRAND and RDSEED instructions. Among other
effects this will reduce throughput from /dev/urandom.

* Enable administrator to configure the mitigation off when desired using
  either mitigations=off or srbds=off.

* Export vulnerability status via sysfs

* Rename file-scoped macros to apply for non-whitelist table initializations.

 [ bp: Massage,
   - s/VULNBL_INTEL_STEPPING/VULNBL_INTEL_STEPPINGS/g,
   - do not read arch cap MSR a second time in tsx_fused_off() - just pass it in,
   - flip check in cpu_set_bug_bits() to save an indentation level,
   - reflow comments.
   jpoimboe: s/Mitigated/Mitigation/ in user-visible strings
   tglx: Dropped the fused off magic for now
 ]

Signed-off-by: Mark Gross 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tony Luck 
Reviewed-by: Pawan Gupta 
Reviewed-by: Josh Poimboeuf 
Tested-by: Neelima Krishnan 
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Add 'table' argument to cpu_matches()

2020-06-10T18:24:57+00:00

commit 93920f61c2ad7edb01e63323832585796af75fc9 upstream

To make cpu_matches() reusable for other matching tables, have it take a
pointer to a x86_cpu_id table as an argument.

 [ bp: Flip arguments order. ]

Signed-off-by: Mark Gross 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Add a steppings field to struct x86_cpu_id

2020-06-10T18:24:57+00:00

commit e9d7144597b10ff13ff2264c059f7d4a7fbc89ac upstream

Intel uses the same family/model for several CPUs. Sometimes the
stepping must be checked to tell them apart.

On x86 there can be at most 16 steppings. Add a steppings bitmask to
x86_cpu_id and a X86_MATCH_VENDOR_FAMILY_MODEL_STEPPING_FEATURE macro
and support for matching against family/model/stepping.

 [ bp: Massage.
   tglx: Lightweight variant for backporting ]

Signed-off-by: Mark Gross 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tony Luck 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/spectre_v2: Exclude Zhaoxin CPUs from SPECTRE_V2

2020-06-10T18:24:57+00:00

commit 1e41a766c98b481400ab8c5a7aa8ea63a1bb03de upstream.

New Zhaoxin family 7 CPUs are not affected by SPECTRE_V2. So define a
separate cpu_vuln_whitelist bit NO_SPECTRE_V2 and add these CPUs to the cpu
vulnerability whitelist.

Signed-off-by: Tony W Wang-oc 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/1579227872-26972-2-git-send-email-TonyWWang-oc@zhaoxin.com
Signed-off-by: Greg Kroah-Hartman

s390/mm: fix set_huge_pte_at() for empty ptes

2020-06-07T11:18:51+00:00

[ Upstream commit ac8372f3b4e41015549b331a4f350224661e7fc6 ]

On s390, the layout of normal and large ptes (i.e. pmds/puds) differs.
Therefore, set_huge_pte_at() does a conversion from a normal pte to
the corresponding large pmd/pud. So, when converting an empty pte, this
should result in an empty pmd/pud, which would return true for
pmd/pud_none().

However, after conversion we also mark the pmd/pud as large, and
therefore present. For empty ptes, this will result in an empty pmd/pud
that is also marked as large, and pmd/pud_none() would not return true.

There is currently no issue with this behaviour, as set_huge_pte_at()
does not seem to be called for empty ptes. It would be valid though, so
let's fix this by not marking empty ptes as large in set_huge_pte_at().

This was found by testing a patch from from Anshuman Khandual, which is
currently discussed on LKML ("mm/debug: Add more arch page table helper
tests").

Signed-off-by: Gerald Schaefer 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Sasha Levin

x86/mmiotrace: Use cpumask_available() for cpumask_var_t variables

2020-06-07T11:18:51+00:00

[ Upstream commit d7110a26e5905ec2fe3fc88bc6a538901accb72b ]

When building with Clang + -Wtautological-compare and
CONFIG_CPUMASK_OFFSTACK unset:

  arch/x86/mm/mmio-mod.c:375:6: warning: comparison of array 'downed_cpus'
  equal to a null pointer is always false [-Wtautological-pointer-compare]
          if (downed_cpus == NULL &&
              ^~~~~~~~~~~    ~~~~
  arch/x86/mm/mmio-mod.c:405:6: warning: comparison of array 'downed_cpus'
  equal to a null pointer is always false [-Wtautological-pointer-compare]
          if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
              ^~~~~~~~~~~    ~~~~
  2 warnings generated.

Commit

  f7e30f01a9e2 ("cpumask: Add helper cpumask_available()")

added cpumask_available() to fix warnings of this nature. Use that here
so that clang does not warn regardless of CONFIG_CPUMASK_OFFSTACK's
value.

Reported-by: Sedat Dilek 
Signed-off-by: Nathan Chancellor 
Signed-off-by: Borislav Petkov 
Reviewed-by: Nick Desaulniers 
Acked-by: Steven Rostedt (VMware) 
Link: https://github.com/ClangBuiltLinux/linux/issues/982
Link: https://lkml.kernel.org/r/20200408205323.44490-1-natechancellor@gmail.com
Signed-off-by: Sasha Levin

ARC: [plat-eznps]: Restrict to CONFIG_ISA_ARCOMPACT

2020-06-07T11:18:50+00:00

[ Upstream commit 799587d5731db9dcdafaac4002463aa7d9cd6cf7 ]

Elide invalid configuration EZNPS + ARCv2, triggered by a
make allyesconfig build.

Granted the root cause is in source code (asm/barrier.h) where we check
for ARCv2 before PLAT_EZNPS, but it is better to avoid such combinations
at onset rather then baking subtle nuances into code.

Reported-by: kbuild test robot 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: Fix ICCM & DCCM runtime size checks

2020-06-07T11:18:50+00:00

[ Upstream commit 43900edf67d7ef3ac8909854d75b8a1fba2d570c ]

As of today the ICCM and DCCM size checks are incorrectly using
mismatched units (KiB checked against bytes). The CONFIG_ARC_DCCM_SZ
and CONFIG_ARC_ICCM_SZ are in KiB, but the size calculated in
runtime and stored in cpu->dccm.sz and cpu->iccm.sz is in bytes.

Fix that.

Reported-by: Paul Greco 
Signed-off-by: Eugeniy Paltsev 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

s390/ftrace: save traced function caller

2020-06-07T11:18:49+00:00

[ Upstream commit b4adfe55915d8363e244e42386d69567db1719b9 ]

A typical backtrace acquired from ftraced function currently looks like
the following (e.g. for "path_openat"):

arch_stack_walk+0x15c/0x2d8
stack_trace_save+0x50/0x68
stack_trace_call+0x15a/0x3b8
ftrace_graph_caller+0x0/0x1c
0x3e0007e3c98 <- ftraced function caller (should be do_filp_open+0x7c/0xe8)
do_open_execat+0x70/0x1b8
__do_execve_file.isra.0+0x7d8/0x860
__s390x_sys_execve+0x56/0x68
system_call+0xdc/0x2d8

Note random "0x3e0007e3c98" stack value as ftraced function caller. This
value causes either imprecise unwinder result or unwinding failure.
That "0x3e0007e3c98" comes from r14 of ftraced function stack frame, which
it haven't had a chance to initialize since the very first instruction
calls ftrace code ("ftrace_caller"). (ftraced function might never
save r14 as well). Nevertheless according to s390 ABI any function
is called with stack frame allocated for it and r14 contains return
address. "ftrace_caller" itself is called with "brasl %r0,ftrace_caller".
So, to fix this issue simply always save traced function caller onto
ftraced function stack frame.

Reported-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Sasha Levin

powerpc/xmon: Restrict when kernel is locked down

2020-06-07T11:18:49+00:00

[ Upstream commit 69393cb03ccdf29f3b452d3482ef918469d1c098 ]

Xmon should be either fully or partially disabled depending on the
kernel lockdown state.

Put xmon into read-only mode for lockdown=integrity and prevent user
entry into xmon when lockdown=confidentiality. Xmon checks the lockdown
state on every attempted entry:

 (1) during early xmon'ing

 (2) when triggered via sysrq

 (3) when toggled via debugfs

 (4) when triggered via a previously enabled breakpoint

The following lockdown state transitions are handled:

 (1) lockdown=none -> lockdown=integrity
     set xmon read-only mode

 (2) lockdown=none -> lockdown=confidentiality
     clear all breakpoints, set xmon read-only mode,
     prevent user re-entry into xmon

 (3) lockdown=integrity -> lockdown=confidentiality
     clear all breakpoints, set xmon read-only mode,
     prevent user re-entry into xmon

Suggested-by: Andrew Donnellan 
Signed-off-by: Christopher M. Riedl 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20190907061124.1947-3-cmr@informatik.wtf
Signed-off-by: Sasha Levin