linux-stable.git/arch, branch v5.2.10

arm64: KVM: regmap: Fix unexpected switch fall-through

2019-08-25T14:10:34+00:00

commit 3d584a3c85d6fe2cf878f220d4ad7145e7f89218 upstream.

When fall-through warnings was enabled by default, commit d93512ef0f0e
("Makefile: Globally enable fall-through warning"), the following
warnings was starting to show up:

In file included from ../arch/arm64/include/asm/kvm_emulate.h:19,
                 from ../arch/arm64/kvm/regmap.c:13:
../arch/arm64/kvm/regmap.c: In function ‘vcpu_write_spsr32’:
../arch/arm64/include/asm/kvm_hyp.h:31:3: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
   asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"), \
   ^~~
../arch/arm64/include/asm/kvm_hyp.h:46:31: note: in expansion of macro ‘write_sysreg_elx’
 #define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)
                               ^~~~~~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:180:3: note: in expansion of macro ‘write_sysreg_el1’
   write_sysreg_el1(v, SYS_SPSR);
   ^~~~~~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:181:2: note: here
  case KVM_SPSR_ABT:
  ^~~~
In file included from ../arch/arm64/include/asm/cputype.h:132,
                 from ../arch/arm64/include/asm/cache.h:8,
                 from ../include/linux/cache.h:6,
                 from ../include/linux/printk.h:9,
                 from ../include/linux/kernel.h:15,
                 from ../include/asm-generic/bug.h:18,
                 from ../arch/arm64/include/asm/bug.h:26,
                 from ../include/linux/bug.h:5,
                 from ../include/linux/mmdebug.h:5,
                 from ../include/linux/mm.h:9,
                 from ../arch/arm64/kvm/regmap.c:11:
../arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
  asm volatile("msr " __stringify(r) ", %x0"  \
  ^~~
../arch/arm64/kvm/regmap.c:182:3: note: in expansion of macro ‘write_sysreg’
   write_sysreg(v, spsr_abt);
   ^~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:183:2: note: here
  case KVM_SPSR_UND:
  ^~~~

Rework to add a 'break;' in the swich-case since it didn't have that,
leading to an interresting set of bugs.

Cc: stable@vger.kernel.org # v4.17+
Fixes: a892819560c4 ("KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers")
Signed-off-by: Anders Roxell 
[maz: reworked commit message, fixed stable range]
Signed-off-by: Marc Zyngier 
Signed-off-by: Greg Kroah-Hartman

page flags: prioritize kasan bits over last-cpuid

2019-08-25T14:10:34+00:00

[ Upstream commit ee38d94a0ad89890b770f6c876263cf9fcbfde84 ]

ARM64 randdconfig builds regularly run into a build error, especially
when NUMA_BALANCING and SPARSEMEM are enabled but not SPARSEMEM_VMEMMAP:

  #error "KASAN: not enough bits in page flags for tag"

The last-cpuid bits are already contitional on the available space, so
the result of the calculation is a bit random on whether they were
already left out or not.

Adding the kasan tag bits before last-cpuid makes it much more likely to
end up with a successful build here, and should be reliable for
randconfig at least, as long as that does not randomize NR_CPUS or
NODES_SHIFT but uses the defaults.

In order for the modified check to not trigger in the x86 vdso32 code
where all constants are wrong (building with -m32), enclose all the
definitions with an #ifdef.

[arnd@arndb.de: build fix]
  Link: http://lkml.kernel.org/r/CAK8P3a3Mno1SWTcuAOT0Wa9VS15pdU6EfnkxLbDpyS55yO04+g@mail.gmail.com
Link: http://lkml.kernel.org/r/20190722115520.3743282-1-arnd@arndb.de
Link: https://lore.kernel.org/lkml/20190618095347.3850490-1-arnd@arndb.de/
Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Arnd Bergmann 
Reviewed-by: Andrey Konovalov 
Reviewed-by: Andrey Ryabinin 
Cc: Andrey Konovalov 
Cc: Dmitry Vyukov 
Cc: Will Deacon 
Cc: Christoph Lameter 
Cc: Mark Rutland 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

arm64: Make debug exception handlers visible from RCU

2019-08-25T14:10:33+00:00

[ Upstream commit d8bb6718c4db9bcd075dde7ff55d46091ccfae15 ]

Make debug exceptions visible from RCU so that synchronize_rcu()
correctly track the debug exception handler.

This also introduces sanity checks for user-mode exceptions as same
as x86's ist_enter()/ist_exit().

The debug exception can interrupt in idle task. For example, it warns
if we put a kprobe on a function called from idle task as below.
The warning message showed that the rcu_read_lock() caused this
problem. But actually, this means the RCU is lost the context which
is already in NMI/IRQ.

  /sys/kernel/debug/tracing # echo p default_idle_call >> kprobe_events
  /sys/kernel/debug/tracing # echo 1 > events/kprobes/enable
  /sys/kernel/debug/tracing # [  135.122237]
  [  135.125035] =============================
  [  135.125310] WARNING: suspicious RCU usage
  [  135.125581] 5.2.0-08445-g9187c508bdc7 #20 Not tainted
  [  135.125904] -----------------------------
  [  135.126205] include/linux/rcupdate.h:594 rcu_read_lock() used illegally while idle!
  [  135.126839]
  [  135.126839] other info that might help us debug this:
  [  135.126839]
  [  135.127410]
  [  135.127410] RCU used illegally from idle CPU!
  [  135.127410] rcu_scheduler_active = 2, debug_locks = 1
  [  135.128114] RCU used illegally from extended quiescent state!
  [  135.128555] 1 lock held by swapper/0/0:
  [  135.128944]  #0: (____ptrval____) (rcu_read_lock){....}, at: call_break_hook+0x0/0x178
  [  135.130499]
  [  135.130499] stack backtrace:
  [  135.131192] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0-08445-g9187c508bdc7 #20
  [  135.131841] Hardware name: linux,dummy-virt (DT)
  [  135.132224] Call trace:
  [  135.132491]  dump_backtrace+0x0/0x140
  [  135.132806]  show_stack+0x24/0x30
  [  135.133133]  dump_stack+0xc4/0x10c
  [  135.133726]  lockdep_rcu_suspicious+0xf8/0x108
  [  135.134171]  call_break_hook+0x170/0x178
  [  135.134486]  brk_handler+0x28/0x68
  [  135.134792]  do_debug_exception+0x90/0x150
  [  135.135051]  el1_dbg+0x18/0x8c
  [  135.135260]  default_idle_call+0x0/0x44
  [  135.135516]  cpu_startup_entry+0x2c/0x30
  [  135.135815]  rest_init+0x1b0/0x280
  [  135.136044]  arch_call_rest_init+0x14/0x1c
  [  135.136305]  start_kernel+0x4d4/0x500
  [  135.136597]

So make debug exception visible to RCU can fix this warning.

Reported-by: Naresh Kamboju 
Acked-by: Paul E. McKenney 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

arm64: kprobes: Recover pstate.D in single-step exception handler

2019-08-25T14:10:33+00:00

[ Upstream commit b3980e48528c4d2a9e70b145a5bba328b73a0f93 ]

kprobes manipulates the interrupted PSTATE for single step, and
doesn't restore it. Thus, if we put a kprobe where the pstate.D
(debug) masked, the mask will be cleared after the kprobe hits.

Moreover, in the most complicated case, this can lead a kernel
crash with below message when a nested kprobe hits.

[  152.118921] Unexpected kernel single-step exception at EL1

When the 1st kprobe hits, do_debug_exception() will be called.
At this point, debug exception (= pstate.D) must be masked (=1).
But if another kprobes hits before single-step of the first kprobe
(e.g. inside user pre_handler), it unmask the debug exception
(pstate.D = 0) and return.
Then, when the 1st kprobe setting up single-step, it saves current
DAIF, mask DAIF, enable single-step, and restore DAIF.
However, since "D" flag in DAIF is cleared by the 2nd kprobe, the
single-step exception happens soon after restoring DAIF.

This has been introduced by commit 7419333fa15e ("arm64: kprobe:
Always clear pstate.D in breakpoint exception handler")

To solve this issue, this stores all DAIF bits and restore it
after single stepping.

Reported-by: Naresh Kamboju 
Fixes: 7419333fa15e ("arm64: kprobe: Always clear pstate.D in breakpoint exception handler")
Reviewed-by: James Morse 
Tested-by: James Morse 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

arm64/mm: fix variable 'tag' set but not used

2019-08-25T14:10:32+00:00

[ Upstream commit 7732d20a160c76006c7fe7bca5178aea6af1d2e8 ]

When CONFIG_KASAN_SW_TAGS=n, set_tag() is compiled away. GCC throws a
warning,

mm/kasan/common.c: In function '__kasan_kmalloc':
mm/kasan/common.c:464:5: warning: variable 'tag' set but not used
[-Wunused-but-set-variable]
  u8 tag = 0xff;
     ^~~

Fix it by making __tag_set() a static inline function the same as
arch_kasan_set_tag() in mm/kasan/kasan.h for consistency because there
is a macro in arch/arm64/include/asm/kasan.h,

 #define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag)

However, when CONFIG_DEBUG_VIRTUAL=n and CONFIG_SPARSEMEM_VMEMMAP=y,
page_to_virt() will call __tag_set() with incorrect type of a
parameter, so fix that as well. Also, still let page_to_virt() return
"void *" instead of "const void *", so will not need to add a similar
cast in lowmem_page_address().

Signed-off-by: Qian Cai 
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

arm64/mm: fix variable 'pud' set but not used

2019-08-25T14:10:32+00:00

[ Upstream commit 7d4e2dcf311d3b98421d1f119efe5964cafa32fc ]

GCC throws a warning,

arch/arm64/mm/mmu.c: In function 'pud_free_pmd_page':
arch/arm64/mm/mmu.c:1033:8: warning: variable 'pud' set but not used
[-Wunused-but-set-variable]
  pud_t pud;
        ^~~

because pud_table() is a macro and compiled away. Fix it by making it a
static inline function and for pud_sect() as well.

Signed-off-by: Qian Cai 
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

arm64: unwind: Prohibit probing on return_address()

2019-08-25T14:10:32+00:00

[ Upstream commit ee07b93e7721ccd5d5b9fa6f0c10cb3fe2f1f4f9 ]

Prohibit probing on return_address() and subroutines which
is called from return_address(), since the it is invoked from
trace_hardirqs_off() which is also kprobe blacklisted.

Reported-by: Naresh Kamboju 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

arm64: Lower priority mask for GIC_PRIO_IRQON

2019-08-25T14:10:31+00:00

[ Upstream commit 677379bc9139ac24b310a281fcb21a2f04288353 ]

On a system with two security states, if SCR_EL3.FIQ is cleared,
non-secure IRQ priorities get shifted to fit the secure view but
priority masks aren't.

On such system, it turns out that GIC_PRIO_IRQON masks the priority of
normal interrupts, which obviously ends up in a hang.

Increase GIC_PRIO_IRQON value (i.e. lower priority) to make sure
interrupts are not blocked by it.

Cc: Oleg Nesterov 
Fixes: bd82d4bd21880b7c ("arm64: Fix incorrect irqflag restore for priority masking")
Acked-by: Marc Zyngier 
Signed-off-by: Julien Thierry 
Signed-off-by: Catalin Marinas 
[will: fixed Fixes: tag]
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

riscv: Fix perf record without libelf support

2019-08-25T14:10:31+00:00

[ Upstream commit b399abe7c21e248dc6224cadc9a378a2beb10cfd ]

This patch fix following perf record error by linking vdso.so with
build id.

perf.data      perf.data.old
[ perf record: Woken up 1 times to write data ]
free(): double free detected in tcache 2
Aborted

perf record use filename__read_build_id(util/symbol-minimal.c) to get
build id when libelf is not supported. When vdso.so is linked without
build id, the section size of PT_NOTE will be zero, buf size will
realloc to zero and cause memory corruption.

Signed-off-by: Mao Han 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Signed-off-by: Paul Walmsley 
Signed-off-by: Sasha Levin

arm64/efi: fix variable 'si' set but not used

2019-08-25T14:10:31+00:00

[ Upstream commit f1d4836201543e88ebe70237e67938168d5fab19 ]

GCC throws out this warning on arm64.

drivers/firmware/efi/libstub/arm-stub.c: In function 'efi_entry':
drivers/firmware/efi/libstub/arm-stub.c:132:22: warning: variable 'si'
set but not used [-Wunused-but-set-variable]

Fix it by making free_screen_info() a static inline function.

Acked-by: Will Deacon 
Signed-off-by: Qian Cai 
Signed-off-by: Catalin Marinas 
Signed-off-by: Sasha Levin