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  1. 22 8月, 2019 1 次提交
  3. 21 8月, 2019 1 次提交
  5. 11 8月, 2019 1 次提交
  7. 10 8月, 2019 6 次提交
    • G
      ARM: ep93xx: Mark expected switch fall-through · 1f7585f3
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

Fix the following warnings (Building: arm-ep93xx_defconfig arm):

arch/arm/mach-ep93xx/crunch.c: In function 'crunch_do':
arch/arm/mach-ep93xx/crunch.c:46:3: warning: this statement may
fall through [-Wimplicit-fallthrough=]
      memset(crunch_state, 0, sizeof(*crunch_state));
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/arm/mach-ep93xx/crunch.c:53:2: note: here
     case THREAD_NOTIFY_EXIT:
     ^~~~

Notice that, in this particular case, the code comment is
modified in accordance with what GCC is expecting to find.
Reported-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      1f7585f3
    • G
      ARM: signal: Mark expected switch fall-through · e9d81fc5
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

This patch fixes the following warning:

arch/arm/kernel/signal.c: In function 'do_signal':
arch/arm/kernel/signal.c:598:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
    restart -= 2;
    ~~~~~~~~^~~~
arch/arm/kernel/signal.c:599:3: note: here
   case -ERESTARTNOHAND:
   ^~~~
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      e9d81fc5
    • G
      ARM: OMAP: dma: Mark expected switch fall-throughs · 3da6bd94
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/plat-omap/dma.c: In function 'omap_set_dma_src_burst_mode':
arch/arm/plat-omap/dma.c:384:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:393:2: note: here
  case OMAP_DMA_DATA_BURST_16:
  ^~~~
arch/arm/plat-omap/dma.c:394:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:402:2: note: here
  default:
  ^~~~~~~
arch/arm/plat-omap/dma.c: In function 'omap_set_dma_dest_burst_mode':
arch/arm/plat-omap/dma.c:473:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:481:2: note: here
  default:
  ^~~~~~~

Notice that, in this particular case, the code comment is
modified in accordance with what GCC is expecting to find.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      3da6bd94
    • G
      ARM: alignment: Mark expected switch fall-throughs · e7c0c9f6
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/mm/alignment.c: In function 'thumb2arm':
arch/arm/mm/alignment.c:688:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if ((tinstr & (3 << 9)) == 0x0400) {
      ^
arch/arm/mm/alignment.c:700:2: note: here
  default:
  ^~~~~~~
arch/arm/mm/alignment.c: In function 'do_alignment_t32_to_handler':
arch/arm/mm/alignment.c:753:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
   poffset->un = (tinst2 & 0xff) << 2;
   ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
arch/arm/mm/alignment.c:754:2: note: here
  case 0xe940:
  ^~~~
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      e7c0c9f6
    • G
      ARM: tegra: Mark expected switch fall-through · 9b76ad3a
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

This patch fixes the following warning:

arch/arm/mach-tegra/reset.c: In function 'tegra_cpu_reset_handler_enable':
arch/arm/mach-tegra/reset.c:72:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
   tegra_cpu_reset_handler_set(reset_address);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/arm/mach-tegra/reset.c:74:2: note: here
  case 0:
  ^~~~
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      9b76ad3a
    • G
      ARM/hw_breakpoint: Mark expected switch fall-throughs · 2d0e988d
      由 Gustavo A. R. Silva 提交于 
      Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_arch_parse':
arch/arm/kernel/hw_breakpoint.c:609:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
      ^
arch/arm/kernel/hw_breakpoint.c:611:2: note: here
  case 3:
  ^~~~
arch/arm/kernel/hw_breakpoint.c:613:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
      ^
arch/arm/kernel/hw_breakpoint.c:615:2: note: here
  default:
  ^~~~~~~
arch/arm/kernel/hw_breakpoint.c: In function 'arch_build_bp_info':
arch/arm/kernel/hw_breakpoint.c:544:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if ((hw->ctrl.type != ARM_BREAKPOINT_EXECUTE)
      ^
arch/arm/kernel/hw_breakpoint.c:547:2: note: here
  default:
  ^~~~~~~
In file included from include/linux/kernel.h:11,
                 from include/linux/list.h:9,
                 from include/linux/preempt.h:11,
                 from include/linux/hardirq.h:5,
                 from arch/arm/kernel/hw_breakpoint.c:16:
arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_pending':
include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:136:2: note: in expansion of macro 'unlikely'
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
arch/arm/kernel/hw_breakpoint.c:863:3: note: in expansion of macro 'WARN'
   WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
   ^~~~
arch/arm/kernel/hw_breakpoint.c:864:2: note: here
  case ARM_ENTRY_SYNC_WATCHPOINT:
  ^~~~
arch/arm/kernel/hw_breakpoint.c: In function 'core_has_os_save_restore':
arch/arm/kernel/hw_breakpoint.c:910:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (oslsr & ARM_OSLSR_OSLM0)
      ^
arch/arm/kernel/hw_breakpoint.c:912:2: note: here
  default:
  ^~~~~~~
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
      2d0e988d
  9. 09 8月, 2019 6 次提交
    • H
      s390/vdso: map vdso also for statically linked binaries · 404861e1
      由 Heiko Carstens 提交于 
      s390 does not map the vdso for statically linked binaries, assuming
that this doesn't make sense. See commit fc5243d9 ("[S390]
arch_setup_additional_pages arguments").

However with glibc commit d665367f596d ("linux: Enable vDSO for static
linking as default (BZ#19767)") and commit 5e855c895401 ("s390: Enable
VDSO for static linking") the vdso is also used for statically linked
binaries - if the kernel would make it available.

Therefore map the vdso always, just like all other architectures.
Reported-by: NStefan Liebler <stli@linux.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>
      404861e1
    • M
      KVM: arm: Don't write junk to CP15 registers on reset · c69509c7
      由 Marc Zyngier 提交于 
      At the moment, the way we reset CP15 registers is mildly insane:
We write junk to them, call the reset functions, and then check that
we have something else in them.

The "fun" thing is that this can happen while the guest is running
(PSCI, for example). If anything in KVM has to evaluate the state
of a CP15 register while junk is in there, bad thing may happen.

Let's stop doing that. Instead, we track that we have called a
reset function for that register, and assume that the reset
function has done something.

In the end, the very need of this reset check is pretty dubious,
as it doesn't check everything (a lot of the CP15 reg leave outside
of the cp15_regs[] array). It may well be axed in the near future.
Signed-off-by: NMarc Zyngier <maz@kernel.org>
      c69509c7
    • M
      KVM: arm64: Don't write junk to sysregs on reset · 03fdfb26
      由 Marc Zyngier 提交于 
      At the moment, the way we reset system registers is mildly insane:
We write junk to them, call the reset functions, and then check that
we have something else in them.

The "fun" thing is that this can happen while the guest is running
(PSCI, for example). If anything in KVM has to evaluate the state
of a system register while junk is in there, bad thing may happen.

Let's stop doing that. Instead, we track that we have called a
reset function for that register, and assume that the reset
function has done something. This requires fixing a couple of
sysreg refinition in the trap table.

In the end, the very need of this reset check is pretty dubious,
as it doesn't check everything (a lot of the sysregs leave outside of
the sys_regs[] array). It may well be axed in the near future.
Tested-by: NZenghui Yu <yuzenghui@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
      03fdfb26
    • P
      RISC-V: Remove udivdi3 · 81a48ee4
      由 Palmer Dabbelt 提交于 
      This should never have landed in the first place: it was added as part
of 64-bit divide support for 32-bit systems, but the kernel doesn't
allow this sort of division.  I must have forgotten to remove it.

This patch removes the support.  Since this routine only worked on
64-bit platforms but was only built on 32-bit platforms, it's
essentially just nonsense anyway.
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Link: https://lore.kernel.org/linux-riscv/nycvar.YSQ.7.76.1908061413360.19480@knanqh.ubzr/T/#tReported-by: NEric Lin <tesheng@andestech.com>
Signed-off-by: NPaul Walmsley <paul.walmsley@sifive.com>
      81a48ee4
    • P
      riscv: delay: use do_div() instead of __udivdi3() · 66cc016a
      由 Paul Walmsley 提交于 
      In preparation for removing __udivdi3() from the RISC-V
architecture-specific files, convert its one user to use do_div().
This avoids breaking the RV32 build after __udivdi3() is removed.

This second version removes the assignment of the remainder to an
unused temporary variable.  Thanks to Nicolas Pitre <nico@fluxnic.net>
for the suggestion.
Signed-off-by: NPaul Walmsley <paul.walmsley@sifive.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
      66cc016a
    • J
      arm64: mm: add missing PTE_SPECIAL in pte_mkdevmap on arm64 · 30e23538
      由 Jia He 提交于 
      Without this patch, the MAP_SYNC test case will cause a print_bad_pte
warning on arm64 as follows:

[   25.542693] BUG: Bad page map in process mapdax333 pte:2e8000448800f53 pmd:41ff5f003
[   25.546360] page:ffff7e0010220000 refcount:1 mapcount:-1 mapping:ffff8003e29c7440 index:0x0
[   25.550281] ext4_dax_aops
[   25.550282] name:"__aaabbbcccddd__"
[   25.551553] flags: 0x3ffff0000001002(referenced|reserved)
[   25.555802] raw: 03ffff0000001002 ffff8003dfffa908 0000000000000000 ffff8003e29c7440
[   25.559446] raw: 0000000000000000 0000000000000000 00000001fffffffe 0000000000000000
[   25.563075] page dumped because: bad pte
[   25.564938] addr:0000ffffbe05b000 vm_flags:208000fb anon_vma:0000000000000000 mapping:ffff8003e29c7440 index:0
[   25.574272] file:__aaabbbcccddd__ fault:ext4_dax_fault mmmmap:ext4_file_mmap readpage:0x0
[   25.578799] CPU: 1 PID: 1180 Comm: mapdax333 Not tainted 5.2.0+ #21
[   25.581702] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[   25.585624] Call trace:
[   25.587008]  dump_backtrace+0x0/0x178
[   25.588799]  show_stack+0x24/0x30
[   25.590328]  dump_stack+0xa8/0xcc
[   25.591901]  print_bad_pte+0x18c/0x218
[   25.593628]  unmap_page_range+0x778/0xc00
[   25.595506]  unmap_single_vma+0x94/0xe8
[   25.597304]  unmap_vmas+0x90/0x108
[   25.598901]  unmap_region+0xc0/0x128
[   25.600566]  __do_munmap+0x284/0x3f0
[   25.602245]  __vm_munmap+0x78/0xe0
[   25.603820]  __arm64_sys_munmap+0x34/0x48
[   25.605709]  el0_svc_common.constprop.0+0x78/0x168
[   25.607956]  el0_svc_handler+0x34/0x90
[   25.609698]  el0_svc+0x8/0xc
[...]

The root cause is in _vm_normal_page, without the PTE_SPECIAL bit,
the return value will be incorrectly set to pfn_to_page(pfn) instead
of NULL. Besides, this patch also rewrite the pmd_mkdevmap to avoid
setting PTE_SPECIAL for pmd

The MAP_SYNC test case is as follows(Provided by Yibo Cai)
$#include <stdio.h>
$#include <string.h>
$#include <unistd.h>
$#include <sys/file.h>
$#include <sys/mman.h>

$#ifndef MAP_SYNC
$#define MAP_SYNC 0x80000
$#endif

/* mount -o dax /dev/pmem0 /mnt */
$#define F "/mnt/__aaabbbcccddd__"

int main(void)
{
    int fd;
    char buf[4096];
    void *addr;

    if ((fd = open(F, O_CREAT|O_TRUNC|O_RDWR, 0644)) < 0) {
        perror("open1");
        return 1;
    }

    if (write(fd, buf, 4096) != 4096) {
        perror("lseek");
        return 1;
    }

    addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_SYNC, fd, 0);
    if (addr == MAP_FAILED) {
        perror("mmap");
        printf("did you mount with '-o dax'?\n");
        return 1;
    }

    memset(addr, 0x55, 4096);

    if (munmap(addr, 4096) == -1) {
        perror("munmap");
        return 1;
    }

    close(fd);

    return 0;
}

Fixes: 73b20c84 ("arm64: mm: implement pte_devmap support")
Reported-by: NYibo Cai <Yibo.Cai@arm.com>
Acked-by: NWill Deacon <will@kernel.org>
Acked-by: NRobin Murphy <Robin.Murphy@arm.com>
Signed-off-by: NJia He <justin.he@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
      30e23538
  11. 08 8月, 2019 4 次提交
  13. 07 8月, 2019 2 次提交
  15. 06 8月, 2019 7 次提交
  17. 05 8月, 2019 5 次提交
    • P
      x86: kvm: remove useless calls to kvm_para_available · 57b76bdb
      由 Paolo Bonzini 提交于 
      Most code in arch/x86/kernel/kvm.c is called through x86_hyper_kvm, and thus only
runs if KVM has been detected.  There is no need to check again for the CPUID
base.

Cc: Sergio Lopez <slp@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      57b76bdb
    • G
      KVM: no need to check return value of debugfs_create functions · 3e7093d0
      由 Greg KH 提交于 
      When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Also, when doing this, change kvm_arch_create_vcpu_debugfs() to return
void instead of an integer, as we should not care at all about if this
function actually does anything or not.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <x86@kernel.org>
Cc: <kvm@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      3e7093d0
    • P
      KVM: remove kvm_arch_has_vcpu_debugfs() · 741cbbae
      由 Paolo Bonzini 提交于 
      There is no need for this function as all arches have to implement
kvm_arch_create_vcpu_debugfs() no matter what.  A #define symbol
let us actually simplify the code.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      741cbbae
    • W
      KVM: Fix leak vCPU's VMCS value into other pCPU · 17e433b5
      由 Wanpeng Li 提交于 
      After commit d73eb57b (KVM: Boost vCPUs that are delivering interrupts), a
five years old bug is exposed. Running ebizzy benchmark in three 80 vCPUs VMs
on one 80 pCPUs Skylake server, a lot of rcu_sched stall warning splatting
in the VMs after stress testing:

 INFO: rcu_sched detected stalls on CPUs/tasks: { 4 41 57 62 77} (detected by 15, t=60004 jiffies, g=899, c=898, q=15073)
 Call Trace:
   flush_tlb_mm_range+0x68/0x140
   tlb_flush_mmu.part.75+0x37/0xe0
   tlb_finish_mmu+0x55/0x60
   zap_page_range+0x142/0x190
   SyS_madvise+0x3cd/0x9c0
   system_call_fastpath+0x1c/0x21

swait_active() sustains to be true before finish_swait() is called in
kvm_vcpu_block(), voluntarily preempted vCPUs are taken into account
by kvm_vcpu_on_spin() loop greatly increases the probability condition
kvm_arch_vcpu_runnable(vcpu) is checked and can be true, when APICv
is enabled the yield-candidate vCPU's VMCS RVI field leaks(by
vmx_sync_pir_to_irr()) into spinning-on-a-taken-lock vCPU's current
VMCS.

This patch fixes it by checking conservatively a subset of events.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Marc Zyngier <Marc.Zyngier@arm.com>
Cc: stable@vger.kernel.org
Fixes: 98f4a146 (KVM: add kvm_arch_vcpu_runnable() test to kvm_vcpu_on_spin() loop)
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      17e433b5
    • W
      KVM: LAPIC: Don't need to wakeup vCPU twice afer timer fire · a48d06f9
      由 Wanpeng Li 提交于 
      kvm_set_pending_timer() will take care to wake up the sleeping vCPU which
has pending timer, don't need to check this in apic_timer_expired() again.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      a48d06f9
  19. 03 8月, 2019 1 次提交
  21. 02 8月, 2019 2 次提交
    • M
      arm64: Make debug exception handlers visible from RCU · d8bb6718
      由 Masami Hiramatsu 提交于 
      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: NNaresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: NPaul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NWill Deacon <will@kernel.org>
      d8bb6718
    • M
      arm64: kprobes: Recover pstate.D in single-step exception handler · b3980e48
      由 Masami Hiramatsu 提交于 
      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 7419333f ("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: NNaresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 7419333f ("arm64: kprobe: Always clear pstate.D in breakpoint exception handler")
Reviewed-by: NJames Morse <james.morse@arm.com>
Tested-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NWill Deacon <will@kernel.org>
      b3980e48
  23. 01 8月, 2019 4 次提交