linux-toradex.git/arch/arm64/include, branch v4.4.73

arm64: ensure extension of smp_store_release value

2017-06-14T11:16:27+00:00

commit 994870bead4ab19087a79492400a5478e2906196 upstream.

When an inline assembly operand's type is narrower than the register it
is allocated to, the least significant bits of the register (up to the
operand type's width) are valid, and any other bits are permitted to
contain any arbitrary value. This aligns with the AAPCS64 parameter
passing rules.

Our __smp_store_release() implementation does not account for this, and
implicitly assumes that operands have been zero-extended to the width of
the type being stored to. Thus, we may store unknown values to memory
when the value type is narrower than the pointer type (e.g. when storing
a char to a long).

This patch fixes the issue by casting the value operand to the same
width as the pointer operand in all cases, which ensures that the value
is zero-extended as we expect. We use the same union trickery as
__smp_load_acquire and {READ,WRITE}_ONCE() to avoid GCC complaining that
pointers are potentially cast to narrower width integers in unreachable
paths.

A whitespace issue at the top of __smp_store_release() is also
corrected.

No changes are necessary for __smp_load_acquire(). Load instructions
implicitly clear any upper bits of the register, and the compiler will
only consider the least significant bits of the register as valid
regardless.

Fixes: 47933ad41a86 ("arch: Introduce smp_load_acquire(), smp_store_release()")
Fixes: 878a84d5a8a1 ("arm64: add missing data types in smp_load_acquire/smp_store_release")
Cc:  # 3.14.x-
Acked-by: Will Deacon 
Signed-off-by: Mark Rutland 
Cc: Matthias Kaehlcke 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: entry: improve data abort handling of tagged pointers

2017-06-14T11:16:27+00:00

commit 276e93279a630657fff4b086ba14c95955912dfa upstream.

This backport has a minor difference from the upstream commit: it adds
the asm-uaccess.h file, which is not present in 4.4, because 4.4 does
not have commit b4b8664d291a ("arm64: don't pull uaccess.h into *.S").

Original patch description:

When handling a data abort from EL0, we currently zero the top byte of
the faulting address, as we assume the address is a TTBR0 address, which
may contain a non-zero address tag. However, the address may be a TTBR1
address, in which case we should not zero the top byte. This patch fixes
that. The effect is that the full TTBR1 address is passed to the task's
signal handler (or printed out in the kernel log).

When handling a data abort from EL1, we leave the faulting address
intact, as we assume it's either a TTBR1 address or a TTBR0 address with
tag 0x00. This is true as far as I'm aware, we don't seem to access a
tagged TTBR0 address anywhere in the kernel. Regardless, it's easy to
forget about address tags, and code added in the future may not always
remember to remove tags from addresses before accessing them. So add tag
handling to the EL1 data abort handler as well. This also makes it
consistent with the EL0 data abort handler.

Fixes: d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0")
Reviewed-by: Dave Martin 
Acked-by: Will Deacon 
Signed-off-by: Kristina Martsenko 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: hw_breakpoint: fix watchpoint matching for tagged pointers

2017-06-14T11:16:27+00:00

commit 7dcd9dd8cebe9fa626af7e2358d03a37041a70fb upstream.

This backport has a few small differences from the upstream commit:
 - The address tag is removed in watchpoint_handler() instead of
   get_distance_from_watchpoint(), because 4.4 does not have commit
   fdfeff0f9e3d ("arm64: hw_breakpoint: Handle inexact watchpoint
   addresses").
 - A macro is backported (untagged_addr), as it is not present in 4.4.

Original patch description:

When we take a watchpoint exception, the address that triggered the
watchpoint is found in FAR_EL1. We compare it to the address of each
configured watchpoint to see which one was hit.

The configured watchpoint addresses are untagged, while the address in
FAR_EL1 will have an address tag if the data access was done using a
tagged address. The tag needs to be removed to compare the address to
the watchpoints.

Currently we don't remove it, and as a result can report the wrong
watchpoint as being hit (specifically, always either the highest TTBR0
watchpoint or lowest TTBR1 watchpoint). This patch removes the tag.

Fixes: d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0")
Acked-by: Mark Rutland 
Acked-by: Will Deacon 
Signed-off-by: Kristina Martsenko 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: uaccess: ensure extension of access_ok() addr

2017-05-25T12:30:15+00:00

commit a06040d7a791a9177581dcf7293941bd92400856 upstream.

Our access_ok() simply hands its arguments over to __range_ok(), which
implicitly assummes that the addr parameter is 64 bits wide. This isn't
necessarily true for compat code, which might pass down a 32-bit address
parameter.

In these cases, we don't have a guarantee that the address has been zero
extended to 64 bits, and the upper bits of the register may contain
unknown values, potentially resulting in a suprious failure.

Avoid this by explicitly casting the addr parameter to an unsigned long
(as is done on other architectures), ensuring that the parameter is
widened appropriately.

Fixes: 0aea86a2176c ("arm64: User access library functions")
Acked-by: Will Deacon 
Signed-off-by: Mark Rutland 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: xchg: hazard against entire exchange variable

2017-05-25T12:30:15+00:00

commit fee960bed5e857eb126c4e56dd9ff85938356579 upstream.

The inline assembly in __XCHG_CASE() uses a +Q constraint to hazard
against other accesses to the memory location being exchanged. However,
the pointer passed to the constraint is a u8 pointer, and thus the
hazard only applies to the first byte of the location.

GCC can take advantage of this, assuming that other portions of the
location are unchanged, as demonstrated with the following test case:

union u {
	unsigned long l;
	unsigned int i[2];
};

unsigned long update_char_hazard(union u *u)
{
	unsigned int a, b;

	a = u->i[1];
	asm ("str %1, %0" : "+Q" (*(char *)&u->l) : "r" (0UL));
	b = u->i[1];

	return a ^ b;
}

unsigned long update_long_hazard(union u *u)
{
	unsigned int a, b;

	a = u->i[1];
	asm ("str %1, %0" : "+Q" (*(long *)&u->l) : "r" (0UL));
	b = u->i[1];

	return a ^ b;
}

The linaro 15.08 GCC 5.1.1 toolchain compiles the above as follows when
using -O2 or above:

0000000000000000 :
   0:	d2800001 	mov	x1, #0x0                   	// #0
   4:	f9000001 	str	x1, [x0]
   8:	d2800000 	mov	x0, #0x0                   	// #0
   c:	d65f03c0 	ret

0000000000000010 :
  10:	b9400401 	ldr	w1, [x0,#4]
  14:	d2800002 	mov	x2, #0x0                   	// #0
  18:	f9000002 	str	x2, [x0]
  1c:	b9400400 	ldr	w0, [x0,#4]
  20:	4a000020 	eor	w0, w1, w0
  24:	d65f03c0 	ret

This patch fixes the issue by passing an unsigned long pointer into the
+Q constraint, as we do for our cmpxchg code. This may hazard against
more than is necessary, but this is better than missing a necessary
hazard.

Fixes: 305d454aaa29 ("arm64: atomics: implement native {relaxed, acquire, release} atomics")
Acked-by: Will Deacon 
Signed-off-by: Mark Rutland 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm/arm64: KVM: Enforce unconditional flush to PoC when mapping to stage-2

2017-03-12T05:37:28+00:00

commit 8f36ebaf21fdae99c091c67e8b6fab33969f2667 upstream.

When we fault in a page, we flush it to the PoC (Point of Coherency)
if the faulting vcpu has its own caches off, so that it can observe
the page we just brought it.

But if the vcpu has its caches on, we skip that step. Bad things
happen when *another* vcpu tries to access that page with its own
caches disabled. At that point, there is no garantee that the
data has made it to the PoC, and we access stale data.

The obvious fix is to always flush to PoC when a page is faulted
in, no matter what the state of the vcpu is.

Fixes: 2d58b733c876 ("arm64: KVM: force cache clean on page fault when caches are off")
Reviewed-by: Christoffer Dall 
Signed-off-by: Marc Zyngier 
Signed-off-by: Greg Kroah-Hartman

arm64/ptrace: Avoid uninitialised struct padding in fpr_set()

2017-01-26T07:23:49+00:00

commit aeb1f39d814b2e21e5e5706a48834bfd553d0059 upstream.

This patch adds an explicit __reserved[] field to user_fpsimd_state
to replace what was previously unnamed padding.

This ensures that data in this region are propagated across
assignment rather than being left possibly uninitialised at the
destination.

Fixes: 60ffc30d5652 ("arm64: Exception handling")
Signed-off-by: Dave Martin 
Acked-by: Will Deacon 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: futex.h: Add missing PAN toggling

2016-12-15T16:49:23+00:00

commit 811d61e384e24759372bb3f01772f3744b0a8327 upstream.

futex.h's futex_atomic_cmpxchg_inatomic() does not use the
__futex_atomic_op() macro and needs its own PAN toggling. This was missed
when the feature was implemented.

Fixes: 338d4f49d6f ("arm64: kernel: Add support for Privileged Access Never")
Signed-off-by: James Morse 
Signed-off-by: Will Deacon 
Cc: Mian Yousaf Kaukab 
Signed-off-by: Greg Kroah-Hartman

arm64: cpufeature: Schedule enable() calls instead of calling them via IPI

2016-12-08T06:15:24+00:00

commit 2a6dcb2b5f3e21592ca8dfa198dcce7bec09b020 upstream.

The enable() call for a cpufeature/errata is called using on_each_cpu().
This issues a cross-call IPI to get the work done. Implicitly, this
stashes the running PSTATE in SPSR when the CPU receives the IPI, and
restores it when we return. This means an enable() call can never modify
PSTATE.

To allow PAN to do this, change the on_each_cpu() call to use
stop_machine(). This schedules the work on each CPU which allows
us to modify PSTATE.

This involves changing the protype of all the enable() functions.

enable_cpu_capabilities() is called during boot and enables the feature
on all online CPUs. This path now uses stop_machine(). CPU features for
hotplug'd CPUs are enabled by verify_local_cpu_features() which only
acts on the local CPU, and can already modify the running PSTATE as it
is called from secondary_start_kernel().

Reported-by: Tony Thompson 
Reported-by: Vladimir Murzin 
Signed-off-by: James Morse 
Cc: Suzuki K Poulose 
Signed-off-by: Will Deacon 
[Removed enable() hunks for features/errata v4.4. doesn't have. Changed
 caps->enable arg in enable_cpu_capabilities()]
Signed-off-by: James Morse 
Signed-off-by: Greg Kroah-Hartman

arm64: percpu: rewrite ll/sc loops in assembly

2016-10-28T07:01:35+00:00

commit 1e6e57d9b34a9075d5f9e2048ea7b09756590d11 upstream.

Writing the outer loop of an LL/SC sequence using do {...} while
constructs potentially allows the compiler to hoist memory accesses
between the STXR and the branch back to the LDXR. On CPUs that do not
guarantee forward progress of LL/SC loops when faced with memory
accesses to the same ERG (up to 2k) between the failed STXR and the
branch back, we may end up livelocking.

This patch avoids this issue in our percpu atomics by rewriting the
outer loop as part of the LL/SC inline assembly block.

Fixes: f97fc810798c ("arm64: percpu: Implement this_cpu operations")
Reviewed-by: Mark Rutland 
Tested-by: Mark Rutland 
Signed-off-by: Will Deacon 
Signed-off-by: Greg Kroah-Hartman