linux-stable.git/arch/csky, branch v5.4.232

csky: Fix function name in csky_alignment() and die()

2023-02-06T06:52:49+00:00

commit 751971af2e3615dc5bd12674080bc795505fefeb upstream.

When building ARCH=csky defconfig:

arch/csky/kernel/traps.c: In function 'die':
arch/csky/kernel/traps.c:112:17: error: implicit declaration of function
'make_dead_task' [-Werror=implicit-function-declaration]
  112 |                 make_dead_task(SIGSEGV);
      |                 ^~~~~~~~~~~~~~

The function's name is make_task_dead(), change it so there is no more
build error.

Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.")
Signed-off-by: Nathan Chancellor 
Reviewed-by: Guo Ren 
Link: https://lkml.kernel.org/r/20211227184851.2297759-4-nathan@kernel.org
Signed-off-by: Eric W. Biederman 
Signed-off-by: Eric Biggers 
Signed-off-by: Sasha Levin

exit: Add and use make_task_dead.

2023-02-06T06:52:49+00:00

commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream.

There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Eric Biggers 
Signed-off-by: Sasha Levin

perf: Protect perf_guest_cbs with RCU

2022-01-20T08:19:18+00:00

commit ff083a2d972f56bebfd82409ca62e5dfce950961 upstream.

Protect perf_guest_cbs with RCU to fix multiple possible errors.  Luckily,
all paths that read perf_guest_cbs already require RCU protection, e.g. to
protect the callback chains, so only the direct perf_guest_cbs touchpoints
need to be modified.

Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
Fixed via the READ_ONCE() in rcu_dereference().

Bug #2 is that on weakly-ordered architectures, updates to the callbacks
themselves are not guaranteed to be visible before the pointer is made
visible to readers.  Fixed by the smp_store_release() in
rcu_assign_pointer() when the new pointer is non-NULL.

Bug #3 is that, because the callbacks are global, it's possible for
readers to run in parallel with an unregisters, and thus a module
implementing the callbacks can be unloaded while readers are in flight,
resulting in a use-after-free.  Fixed by a synchronize_rcu() call when
unregistering callbacks.

Bug #1 escaped notice because it's extremely unlikely a compiler will
reload perf_guest_cbs in this sequence.  perf_guest_cbs does get reloaded
for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
guard all but guarantees the consumer will win the race, e.g. to nullify
perf_guest_cbs, KVM has to completely exit the guest and teardown down
all VMs before KVM start its module unload / unregister sequence.  This
also makes it all but impossible to encounter bug #3.

Bug #2 has not been a problem because all architectures that register
callbacks are strongly ordered and/or have a static set of callbacks.

But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
kvm_intel module load/unload leads to:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP
  CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:perf_misc_flags+0x1c/0x70
  Call Trace:
   perf_prepare_sample+0x53/0x6b0
   perf_event_output_forward+0x67/0x160
   __perf_event_overflow+0x52/0xf0
   handle_pmi_common+0x207/0x300
   intel_pmu_handle_irq+0xcf/0x410
   perf_event_nmi_handler+0x28/0x50
   nmi_handle+0xc7/0x260
   default_do_nmi+0x6b/0x170
   exc_nmi+0x103/0x130
   asm_exc_nmi+0x76/0xbf

Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host")
Signed-off-by: Sean Christopherson 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Paolo Bonzini 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com
Signed-off-by: Greg Kroah-Hartman

csky: Fixup regs.sr broken in ptrace

2021-10-20T09:40:12+00:00

commit af89ebaa64de726ca0a39bbb0bf0c81a1f43ad50 upstream.

gpr_get() return the entire pt_regs (include sr) to userspace, if we
don't restore the C bit in gpr_set, it may break the ALU result in
that context. So the C flag bit is part of gpr context, that's why
riscv totally remove the C bit in the ISA. That makes sr reg clear
from userspace to supervisor privilege.

Signed-off-by: Guo Ren 
Cc: Al Viro 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

csky: don't let sigreturn play with priveleged bits of status register

2021-10-20T09:40:12+00:00

commit fbd63c08cdcca5fb1315aca3172b3c9c272cfb4f upstream.

csky restore_sigcontext() blindly overwrites regs->sr with the value
it finds in sigcontext.  Attacker can store whatever they want in there,
which includes things like S-bit.  Userland shouldn't be able to set
that, or anything other than C flag (bit 0).

Do the same thing other architectures with protected bits in flags
register do - preserve everything that shouldn't be settable in
user mode, picking the rest from the value saved is sigcontext.

Signed-off-by: Al Viro 
Signed-off-by: Guo Ren 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

csky: change a Kconfig symbol name to fix e1000 build error

2021-04-28T11:19:16+00:00

[ Upstream commit d199161653d612b8fb96ac51bfd5b2d2782ecef3 ]

e1000's #define of CONFIG_RAM_BASE conflicts with a Kconfig symbol in
arch/csky/Kconfig.

The symbol in e1000 has been around longer, so change arch/csky/ to use
DRAM_BASE instead of RAM_BASE to remove the conflict.  (although e1000
is also a 2-line change)

Link: https://lkml.kernel.org/r/20210411055335.7111-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap 
Reported-by: kernel test robot 
Acked-by: Guo Ren 
Cc: Jesse Brandeburg 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

csky: Fixup abiv2 syscall_trace break a4 & a5

2020-06-17T14:40:21+00:00

[ Upstream commit e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 ]

Current implementation could destory a4 & a5 when strace, so we need to get them
from pt_regs by SAVE_ALL.

Signed-off-by: Guo Ren 
Signed-off-by: Sasha Levin

csky: Fixup raw_copy_from_user()

2020-06-03T06:21:15+00:00

[ Upstream commit 51bb38cb78363fdad1f89e87357b7bc73e39ba88 ]

If raw_copy_from_user(to, from, N) returns K, callers expect
the first N - K bytes starting at to to have been replaced with
the contents of corresponding area starting at from and the last
K bytes of destination *left* *unmodified*.

What arch/sky/lib/usercopy.c is doing is broken - it can lead to e.g.
data corruption on write(2).

raw_copy_to_user() is inaccurate about return value, which is a bug,
but consequences are less drastic than for raw_copy_from_user().
And just what are those access_ok() doing in there?  I mean, look into
linux/uaccess.h; that's where we do that check (as well as zero tail
on failure in the callers that need zeroing).

AFAICS, all of that shouldn't be hard to fix; something like a patch
below might make a useful starting point.

I would suggest moving these macros into usercopy.c (they are never
used anywhere else) and possibly expanding them there; if you leave
them alive, please at least rename __copy_user_zeroing(). Again,
it must not zero anything on failed read.

Said that, I'm not sure we won't be better off simply turning
usercopy.c into usercopy.S - all that is left there is a couple of
functions, each consisting only of inline asm.

Guo Ren reply:

Yes, raw_copy_from_user is wrong, it's no need zeroing code.

unsigned long _copy_from_user(void *to, const void __user *from,
unsigned long n)
{
        unsigned long res = n;
        might_fault();
        if (likely(access_ok(from, n))) {
                kasan_check_write(to, n);
                res = raw_copy_from_user(to, from, n);
        }
        if (unlikely(res))
                memset(to + (n - res), 0, res);
        return res;
}
EXPORT_SYMBOL(_copy_from_user);

You are right and access_ok() should be removed.

but, how about:
do {
...
        "2:     stw     %3, (%1, 0)     \n"             \
+       "       subi    %0, 4          \n"               \
        "9:     stw     %4, (%1, 4)     \n"             \
+       "       subi    %0, 4          \n"               \
        "10:    stw     %5, (%1, 8)     \n"             \
+       "       subi    %0, 4          \n"               \
        "11:    stw     %6, (%1, 12)    \n"             \
+       "       subi    %0, 4          \n"               \
        "       addi    %2, 16          \n"             \
        "       addi    %1, 16          \n"             \

Don't expand __ex_table

AI Viro reply:

Hey, I've no idea about the instruction scheduling on csky -
if that doesn't slow the things down, all the better.  It's just
that copy_to_user() and friends are on fairly hot codepaths,
and in quite a few situations they will dominate the speed of
e.g. read(2).  So I tried to keep the fast path unchanged.
Up to the architecture maintainers, obviously.  Which would be
you...

As for the fixups size increase (__ex_table size is unchanged)...
You have each of those macros expanded exactly once.
So the size is not a serious argument, IMO - useless complexity
would be, if it is, in fact, useless; the size... not really,
especially since those extra subi will at least offset it.

Again, up to you - asm optimizations of (essentially)
memcpy()-style loops are tricky and can depend upon the
fairly subtle details of architecture.  So even on something
I know reasonably well I would resort to direct experiments
if I can't pass the buck to architecture maintainers.

It *is* worth optimizing - this is where read() from a file
that is already in page cache spends most of the time, etc.

Guo Ren reply:

Thx, after fixup some typo “sub %0, 4”, apply the patch.

TODO:
 - user copy/from codes are still need optimizing.

Signed-off-by: Al Viro 
Signed-off-by: Guo Ren 
Signed-off-by: Sasha Levin

csky: Fixup remove duplicate irq_disable

2020-06-03T06:21:14+00:00

[ Upstream commit 6633a5aa8eb6bda70eb3a9837efd28a67ccc6e0a ]

Interrupt has been disabled in __schedule() with local_irq_disable()
and enabled in finish_task_switch->finish_lock_switch() with
local_irq_enabled(), So needn't to disable irq here.

Signed-off-by: Liu Yibin 
Signed-off-by: Guo Ren 
Signed-off-by: Sasha Levin

csky: Fixup perf callchain unwind

2020-06-03T06:21:14+00:00

[ Upstream commit 229a0ddee1108a3f82a873e6cbbe35c92c540444 ]

 [ 5221.974084] Unable to handle kernel paging request at virtual address 0xfffff000, pc: 0x8002c18e
 [ 5221.985929] Oops: 00000000
 [ 5221.989488]
 [ 5221.989488] CURRENT PROCESS:
 [ 5221.989488]
 [ 5221.992877] COMM=callchain_test PID=11962
 [ 5221.995213] TEXT=00008000-000087e0 DATA=00009f1c-0000a018 BSS=0000a018-0000b000
 [ 5221.999037] USER-STACK=7fc18e20  KERNEL-STACK=be204680
 [ 5221.999037]
 [ 5222.003292] PC: 0x8002c18e (perf_callchain_kernel+0x3e/0xd4)
 [ 5222.007957] LR: 0x8002c198 (perf_callchain_kernel+0x48/0xd4)
 [ 5222.074873] Call Trace:
 [ 5222.074873] [<800a248e>] get_perf_callchain+0x20a/0x29c
 [ 5222.074873] [<8009d964>] perf_callchain+0x64/0x80
 [ 5222.074873] [<8009dc1c>] perf_prepare_sample+0x29c/0x4b8
 [ 5222.074873] [<8009de6e>] perf_event_output_forward+0x36/0x98
 [ 5222.074873] [<800497e0>] search_exception_tables+0x20/0x44
 [ 5222.074873] [<8002cbb6>] do_page_fault+0x92/0x378
 [ 5222.074873] [<80098608>] __perf_event_overflow+0x54/0xdc
 [ 5222.074873] [<80098778>] perf_swevent_hrtimer+0xe8/0x164
 [ 5222.074873] [<8002ddd0>] update_mmu_cache+0x0/0xd8
 [ 5222.074873] [<8002c014>] user_backtrace+0x58/0xc4
 [ 5222.074873] [<8002c0b4>] perf_callchain_user+0x34/0xd0
 [ 5222.074873] [<800a2442>] get_perf_callchain+0x1be/0x29c
 [ 5222.074873] [<8009d964>] perf_callchain+0x64/0x80
 [ 5222.074873] [<8009d834>] perf_output_sample+0x78c/0x858
 [ 5222.074873] [<8009dc1c>] perf_prepare_sample+0x29c/0x4b8
 [ 5222.074873] [<8009de94>] perf_event_output_forward+0x5c/0x98
 [ 5222.097846]
 [ 5222.097846] [<800a0300>] perf_event_exit_task+0x58/0x43c
 [ 5222.097846] [<8006c874>] hrtimer_interrupt+0x104/0x2ec
 [ 5222.097846] [<800a0300>] perf_event_exit_task+0x58/0x43c
 [ 5222.097846] [<80437bb6>] dw_apb_clockevent_irq+0x2a/0x4c
 [ 5222.097846] [<8006c770>] hrtimer_interrupt+0x0/0x2ec
 [ 5222.097846] [<8005f2e4>] __handle_irq_event_percpu+0xac/0x19c
 [ 5222.097846] [<80437bb6>] dw_apb_clockevent_irq+0x2a/0x4c
 [ 5222.097846] [<8005f408>] handle_irq_event_percpu+0x34/0x88
 [ 5222.097846] [<8005f480>] handle_irq_event+0x24/0x64
 [ 5222.097846] [<8006218c>] handle_level_irq+0x68/0xdc
 [ 5222.097846] [<8005ec76>] __handle_domain_irq+0x56/0xa8
 [ 5222.097846] [<80450e90>] ck_irq_handler+0xac/0xe4
 [ 5222.097846] [<80029012>] csky_do_IRQ+0x12/0x24
 [ 5222.097846] [<8002a3a0>] csky_irq+0x70/0x80
 [ 5222.097846] [<800ca612>] alloc_set_pte+0xd2/0x238
 [ 5222.097846] [<8002ddd0>] update_mmu_cache+0x0/0xd8
 [ 5222.097846] [<800a0340>] perf_event_exit_task+0x98/0x43c

The original fp check doesn't base on the real kernal stack region.
Invalid fp address may cause kernel panic.

Signed-off-by: Mao Han 
Signed-off-by: Guo Ren 
Signed-off-by: Sasha Levin