<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/arch/arm64/include/asm, branch linux-6.11.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>KVM: arm64: Get rid of userspace_irqchip_in_use</title>
<updated>2024-12-05T12:54:10+00:00</updated>
<author>
<name>Raghavendra Rao Ananta</name>
<email>rananta@google.com</email>
</author>
<published>2024-10-28T23:45:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c16e2dba39ff6ae84bb8dc9c8e0fb21d9b2f6f5c'/>
<id>c16e2dba39ff6ae84bb8dc9c8e0fb21d9b2f6f5c</id>
<content type='text'>
commit 38d7aacca09230fdb98a34194fec2af597e8e20d upstream.

Improper use of userspace_irqchip_in_use led to syzbot hitting the
following WARN_ON() in kvm_timer_update_irq():

WARNING: CPU: 0 PID: 3281 at arch/arm64/kvm/arch_timer.c:459
kvm_timer_update_irq+0x21c/0x394
Call trace:
  kvm_timer_update_irq+0x21c/0x394 arch/arm64/kvm/arch_timer.c:459
  kvm_timer_vcpu_reset+0x158/0x684 arch/arm64/kvm/arch_timer.c:968
  kvm_reset_vcpu+0x3b4/0x560 arch/arm64/kvm/reset.c:264
  kvm_vcpu_set_target arch/arm64/kvm/arm.c:1553 [inline]
  kvm_arch_vcpu_ioctl_vcpu_init arch/arm64/kvm/arm.c:1573 [inline]
  kvm_arch_vcpu_ioctl+0x112c/0x1b3c arch/arm64/kvm/arm.c:1695
  kvm_vcpu_ioctl+0x4ec/0xf74 virt/kvm/kvm_main.c:4658
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:907 [inline]
  __se_sys_ioctl fs/ioctl.c:893 [inline]
  __arm64_sys_ioctl+0x108/0x184 fs/ioctl.c:893
  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
  invoke_syscall+0x78/0x1b8 arch/arm64/kernel/syscall.c:49
  el0_svc_common+0xe8/0x1b0 arch/arm64/kernel/syscall.c:132
  do_el0_svc+0x40/0x50 arch/arm64/kernel/syscall.c:151
  el0_svc+0x54/0x14c arch/arm64/kernel/entry-common.c:712
  el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

The following sequence led to the scenario:
 - Userspace creates a VM and a vCPU.
 - The vCPU is initialized with KVM_ARM_VCPU_PMU_V3 during
   KVM_ARM_VCPU_INIT.
 - Without any other setup, such as vGIC or vPMU, userspace issues
   KVM_RUN on the vCPU. Since the vPMU is requested, but not setup,
   kvm_arm_pmu_v3_enable() fails in kvm_arch_vcpu_run_pid_change().
   As a result, KVM_RUN returns after enabling the timer, but before
   incrementing 'userspace_irqchip_in_use':
   kvm_arch_vcpu_run_pid_change()
       ret = kvm_arm_pmu_v3_enable()
           if (!vcpu-&gt;arch.pmu.created)
               return -EINVAL;
       if (ret)
           return ret;
       [...]
       if (!irqchip_in_kernel(kvm))
           static_branch_inc(&amp;userspace_irqchip_in_use);
 - Userspace ignores the error and issues KVM_ARM_VCPU_INIT again.
   Since the timer is already enabled, control moves through the
   following flow, ultimately hitting the WARN_ON():
   kvm_timer_vcpu_reset()
       if (timer-&gt;enabled)
          kvm_timer_update_irq()
              if (!userspace_irqchip())
                  ret = kvm_vgic_inject_irq()
                      ret = vgic_lazy_init()
                          if (unlikely(!vgic_initialized(kvm)))
                              if (kvm-&gt;arch.vgic.vgic_model !=
                                  KVM_DEV_TYPE_ARM_VGIC_V2)
                                      return -EBUSY;
                  WARN_ON(ret);

Theoretically, since userspace_irqchip_in_use's functionality can be
simply replaced by '!irqchip_in_kernel()', get rid of the static key
to avoid the mismanagement, which also helps with the syzbot issue.

Cc: &lt;stable@vger.kernel.org&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Suggested-by: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Raghavendra Rao Ananta &lt;rananta@google.com&gt;
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 38d7aacca09230fdb98a34194fec2af597e8e20d upstream.

Improper use of userspace_irqchip_in_use led to syzbot hitting the
following WARN_ON() in kvm_timer_update_irq():

WARNING: CPU: 0 PID: 3281 at arch/arm64/kvm/arch_timer.c:459
kvm_timer_update_irq+0x21c/0x394
Call trace:
  kvm_timer_update_irq+0x21c/0x394 arch/arm64/kvm/arch_timer.c:459
  kvm_timer_vcpu_reset+0x158/0x684 arch/arm64/kvm/arch_timer.c:968
  kvm_reset_vcpu+0x3b4/0x560 arch/arm64/kvm/reset.c:264
  kvm_vcpu_set_target arch/arm64/kvm/arm.c:1553 [inline]
  kvm_arch_vcpu_ioctl_vcpu_init arch/arm64/kvm/arm.c:1573 [inline]
  kvm_arch_vcpu_ioctl+0x112c/0x1b3c arch/arm64/kvm/arm.c:1695
  kvm_vcpu_ioctl+0x4ec/0xf74 virt/kvm/kvm_main.c:4658
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:907 [inline]
  __se_sys_ioctl fs/ioctl.c:893 [inline]
  __arm64_sys_ioctl+0x108/0x184 fs/ioctl.c:893
  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
  invoke_syscall+0x78/0x1b8 arch/arm64/kernel/syscall.c:49
  el0_svc_common+0xe8/0x1b0 arch/arm64/kernel/syscall.c:132
  do_el0_svc+0x40/0x50 arch/arm64/kernel/syscall.c:151
  el0_svc+0x54/0x14c arch/arm64/kernel/entry-common.c:712
  el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

The following sequence led to the scenario:
 - Userspace creates a VM and a vCPU.
 - The vCPU is initialized with KVM_ARM_VCPU_PMU_V3 during
   KVM_ARM_VCPU_INIT.
 - Without any other setup, such as vGIC or vPMU, userspace issues
   KVM_RUN on the vCPU. Since the vPMU is requested, but not setup,
   kvm_arm_pmu_v3_enable() fails in kvm_arch_vcpu_run_pid_change().
   As a result, KVM_RUN returns after enabling the timer, but before
   incrementing 'userspace_irqchip_in_use':
   kvm_arch_vcpu_run_pid_change()
       ret = kvm_arm_pmu_v3_enable()
           if (!vcpu-&gt;arch.pmu.created)
               return -EINVAL;
       if (ret)
           return ret;
       [...]
       if (!irqchip_in_kernel(kvm))
           static_branch_inc(&amp;userspace_irqchip_in_use);
 - Userspace ignores the error and issues KVM_ARM_VCPU_INIT again.
   Since the timer is already enabled, control moves through the
   following flow, ultimately hitting the WARN_ON():
   kvm_timer_vcpu_reset()
       if (timer-&gt;enabled)
          kvm_timer_update_irq()
              if (!userspace_irqchip())
                  ret = kvm_vgic_inject_irq()
                      ret = vgic_lazy_init()
                          if (unlikely(!vgic_initialized(kvm)))
                              if (kvm-&gt;arch.vgic.vgic_model !=
                                  KVM_DEV_TYPE_ARM_VGIC_V2)
                                      return -EBUSY;
                  WARN_ON(ret);

Theoretically, since userspace_irqchip_in_use's functionality can be
simply replaced by '!irqchip_in_kernel()', get rid of the static key
to avoid the mismanagement, which also helps with the syzbot issue.

Cc: &lt;stable@vger.kernel.org&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Suggested-by: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Raghavendra Rao Ananta &lt;rananta@google.com&gt;
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: probes: Disable kprobes/uprobes on MOPS instructions</title>
<updated>2024-12-05T12:52:43+00:00</updated>
<author>
<name>Kristina Martsenko</name>
<email>kristina.martsenko@arm.com</email>
</author>
<published>2024-09-30T16:10:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=428b40d4d0e1ca130d1176f18081b894c9646af6'/>
<id>428b40d4d0e1ca130d1176f18081b894c9646af6</id>
<content type='text'>
[ Upstream commit c56c599d9002d44f559be3852b371db46adac87c ]

FEAT_MOPS instructions require that all three instructions (prologue,
main and epilogue) appear consecutively in memory. Placing a
kprobe/uprobe on one of them doesn't work as only a single instruction
gets executed out-of-line or simulated. So don't allow placing a probe
on a MOPS instruction.

Fixes: b7564127ffcb ("arm64: mops: detect and enable FEAT_MOPS")
Signed-off-by: Kristina Martsenko &lt;kristina.martsenko@arm.com&gt;
Link: https://lore.kernel.org/r/20240930161051.3777828-2-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit c56c599d9002d44f559be3852b371db46adac87c ]

FEAT_MOPS instructions require that all three instructions (prologue,
main and epilogue) appear consecutively in memory. Placing a
kprobe/uprobe on one of them doesn't work as only a single instruction
gets executed out-of-line or simulated. So don't allow placing a probe
on a MOPS instruction.

Fixes: b7564127ffcb ("arm64: mops: detect and enable FEAT_MOPS")
Signed-off-by: Kristina Martsenko &lt;kristina.martsenko@arm.com&gt;
Link: https://lore.kernel.org/r/20240930161051.3777828-2-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling</title>
<updated>2024-11-22T14:39:55+00:00</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2024-10-29T18:11:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c550eec47df8a8e69d4be24ab0c5ce2f022d3d04'/>
<id>c550eec47df8a8e69d4be24ab0c5ce2f022d3d04</id>
<content type='text'>
[ Upstream commit 5baf8b037debf4ec60108ccfeccb8636d1dbad81 ]

Currently MTE is permitted in two circumstances (desiring to use MTE
having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is
specified, as checked by arch_calc_vm_flag_bits() and actualised by
setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is
shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap
hook is activated in mmap_region().

The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also
set is the arm64 implementation of arch_validate_flags().

Unfortunately, we intend to refactor mmap_region() to perform this check
earlier, meaning that in the case of a shmem backing we will not have
invoked shmem_mmap() yet, causing the mapping to fail spuriously.

It is inappropriate to set this architecture-specific flag in general mm
code anyway, so a sensible resolution of this issue is to instead move the
check somewhere else.

We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via
the arch_calc_vm_flag_bits() call.

This is an appropriate place to do this as we already check for the
MAP_ANONYMOUS case here, and the shmem file case is simply a variant of
the same idea - we permit RAM-backed memory.

This requires a modification to the arch_calc_vm_flag_bits() signature to
pass in a pointer to the struct file associated with the mapping, however
this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.

So this patch performs this adjustment and removes the unnecessary
assignment of VM_MTE_ALLOWED in shmem_mmap().

[akpm@linux-foundation.org: fix whitespace, per Catalin]
Link: https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com
Fixes: deb0f6562884 ("mm/mmap: undo -&gt;mmap() when arch_validate_flags() fails")
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Suggested-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Reported-by: Jann Horn &lt;jannh@google.com&gt;
Reviewed-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Andreas Larsson &lt;andreas@gaisler.com&gt;
Cc: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: James E.J. Bottomley &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 5baf8b037debf4ec60108ccfeccb8636d1dbad81 ]

Currently MTE is permitted in two circumstances (desiring to use MTE
having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is
specified, as checked by arch_calc_vm_flag_bits() and actualised by
setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is
shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap
hook is activated in mmap_region().

The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also
set is the arm64 implementation of arch_validate_flags().

Unfortunately, we intend to refactor mmap_region() to perform this check
earlier, meaning that in the case of a shmem backing we will not have
invoked shmem_mmap() yet, causing the mapping to fail spuriously.

It is inappropriate to set this architecture-specific flag in general mm
code anyway, so a sensible resolution of this issue is to instead move the
check somewhere else.

We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via
the arch_calc_vm_flag_bits() call.

This is an appropriate place to do this as we already check for the
MAP_ANONYMOUS case here, and the shmem file case is simply a variant of
the same idea - we permit RAM-backed memory.

This requires a modification to the arch_calc_vm_flag_bits() signature to
pass in a pointer to the struct file associated with the mapping, however
this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.

So this patch performs this adjustment and removes the unnecessary
assignment of VM_MTE_ALLOWED in shmem_mmap().

[akpm@linux-foundation.org: fix whitespace, per Catalin]
Link: https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com
Fixes: deb0f6562884 ("mm/mmap: undo -&gt;mmap() when arch_validate_flags() fails")
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Suggested-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Reported-by: Jann Horn &lt;jannh@google.com&gt;
Reviewed-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Andreas Larsson &lt;andreas@gaisler.com&gt;
Cc: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: James E.J. Bottomley &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: probes: Fix uprobes for big-endian kernels</title>
<updated>2024-10-22T13:51:19+00:00</updated>
<author>
<name>Mark Rutland</name>
<email>mark.rutland@arm.com</email>
</author>
<published>2024-10-08T15:58:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3d2530c65be04e93720e30f191a7cf1a3aa8b51c'/>
<id>3d2530c65be04e93720e30f191a7cf1a3aa8b51c</id>
<content type='text'>
commit 13f8f1e05f1dc36dbba6cba0ae03354c0dafcde7 upstream.

The arm64 uprobes code is broken for big-endian kernels as it doesn't
convert the in-memory instruction encoding (which is always
little-endian) into the kernel's native endianness before analyzing and
simulating instructions. This may result in a few distinct problems:

* The kernel may may erroneously reject probing an instruction which can
  safely be probed.

* The kernel may erroneously erroneously permit stepping an
  instruction out-of-line when that instruction cannot be stepped
  out-of-line safely.

* The kernel may erroneously simulate instruction incorrectly dur to
  interpretting the byte-swapped encoding.

The endianness mismatch isn't caught by the compiler or sparse because:

* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so
  the compiler and sparse have no idea these contain a little-endian
  32-bit value. The core uprobes code populates these with a memcpy()
  which similarly does not handle endianness.

* While the uprobe_opcode_t type is an alias for __le32, both
  arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[]
  to the similarly-named probe_opcode_t, which is an alias for u32.
  Hence there is no endianness conversion warning.

Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and
adding the appropriate __le32_to_cpu() conversions prior to consuming
the instruction encoding. The core uprobes copies these fields as opaque
ranges of bytes, and so is unaffected by this change.

At the same time, remove MAX_UINSN_BYTES and consistently use
AARCH64_INSN_SIZE for clarity.

Tested with the following:

| #include &lt;stdio.h&gt;
| #include &lt;stdbool.h&gt;
|
| #define noinline __attribute__((noinline))
|
| static noinline void *adrp_self(void)
| {
|         void *addr;
|
|         asm volatile(
|         "       adrp    %x0, adrp_self\n"
|         "       add     %x0, %x0, :lo12:adrp_self\n"
|         : "=r" (addr));
| }
|
|
| int main(int argc, char *argv)
| {
|         void *ptr = adrp_self();
|         bool equal = (ptr == adrp_self);
|
|         printf("adrp_self   =&gt; %p\n"
|                "adrp_self() =&gt; %p\n"
|                "%s\n",
|                adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL");
|
|         return 0;
| }

.... where the adrp_self() function was compiled to:

| 00000000004007e0 &lt;adrp_self&gt;:
|   4007e0:       90000000        adrp    x0, 400000 &lt;__ehdr_start&gt;
|   4007e4:       911f8000        add     x0, x0, #0x7e0
|   4007e8:       d65f03c0        ret

Before this patch, the ADRP is not recognized, and is assumed to be
steppable, resulting in corruption of the result:

| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL
| # echo 'p /root/adrp-self:0x007e0' &gt; /sys/kernel/tracing/uprobe_events
| # echo 1 &gt; /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0xffffffffff7e0
| NOT EQUAL

After this patch, the ADRP is correctly recognized and simulated:

| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL
| #
| # echo 'p /root/adrp-self:0x007e0' &gt; /sys/kernel/tracing/uprobe_events
| # echo 1 &gt; /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL

Fixes: 9842ceae9fa8 ("arm64: Add uprobe support")
Cc: stable@vger.kernel.org
Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20241008155851.801546-4-mark.rutland@arm.com
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 13f8f1e05f1dc36dbba6cba0ae03354c0dafcde7 upstream.

The arm64 uprobes code is broken for big-endian kernels as it doesn't
convert the in-memory instruction encoding (which is always
little-endian) into the kernel's native endianness before analyzing and
simulating instructions. This may result in a few distinct problems:

* The kernel may may erroneously reject probing an instruction which can
  safely be probed.

* The kernel may erroneously erroneously permit stepping an
  instruction out-of-line when that instruction cannot be stepped
  out-of-line safely.

* The kernel may erroneously simulate instruction incorrectly dur to
  interpretting the byte-swapped encoding.

The endianness mismatch isn't caught by the compiler or sparse because:

* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so
  the compiler and sparse have no idea these contain a little-endian
  32-bit value. The core uprobes code populates these with a memcpy()
  which similarly does not handle endianness.

* While the uprobe_opcode_t type is an alias for __le32, both
  arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[]
  to the similarly-named probe_opcode_t, which is an alias for u32.
  Hence there is no endianness conversion warning.

Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and
adding the appropriate __le32_to_cpu() conversions prior to consuming
the instruction encoding. The core uprobes copies these fields as opaque
ranges of bytes, and so is unaffected by this change.

At the same time, remove MAX_UINSN_BYTES and consistently use
AARCH64_INSN_SIZE for clarity.

Tested with the following:

| #include &lt;stdio.h&gt;
| #include &lt;stdbool.h&gt;
|
| #define noinline __attribute__((noinline))
|
| static noinline void *adrp_self(void)
| {
|         void *addr;
|
|         asm volatile(
|         "       adrp    %x0, adrp_self\n"
|         "       add     %x0, %x0, :lo12:adrp_self\n"
|         : "=r" (addr));
| }
|
|
| int main(int argc, char *argv)
| {
|         void *ptr = adrp_self();
|         bool equal = (ptr == adrp_self);
|
|         printf("adrp_self   =&gt; %p\n"
|                "adrp_self() =&gt; %p\n"
|                "%s\n",
|                adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL");
|
|         return 0;
| }

.... where the adrp_self() function was compiled to:

| 00000000004007e0 &lt;adrp_self&gt;:
|   4007e0:       90000000        adrp    x0, 400000 &lt;__ehdr_start&gt;
|   4007e4:       911f8000        add     x0, x0, #0x7e0
|   4007e8:       d65f03c0        ret

Before this patch, the ADRP is not recognized, and is assumed to be
steppable, resulting in corruption of the result:

| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL
| # echo 'p /root/adrp-self:0x007e0' &gt; /sys/kernel/tracing/uprobe_events
| # echo 1 &gt; /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0xffffffffff7e0
| NOT EQUAL

After this patch, the ADRP is correctly recognized and simulated:

| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL
| #
| # echo 'p /root/adrp-self:0x007e0' &gt; /sys/kernel/tracing/uprobe_events
| # echo 1 &gt; /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   =&gt; 0x4007e0
| adrp_self() =&gt; 0x4007e0
| EQUAL

Fixes: 9842ceae9fa8 ("arm64: Add uprobe support")
Cc: stable@vger.kernel.org
Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20241008155851.801546-4-mark.rutland@arm.com
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: cputype: Add Neoverse-N3 definitions</title>
<updated>2024-10-10T10:04:13+00:00</updated>
<author>
<name>Mark Rutland</name>
<email>mark.rutland@arm.com</email>
</author>
<published>2024-10-07T12:04:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=77300a241efa3ce88d17c3f59c454dba3618e1cd'/>
<id>77300a241efa3ce88d17c3f59c454dba3618e1cd</id>
<content type='text'>
[ Upstream commit 924725707d80bc2588cefafef76ff3f164d299bc ]

Add cputype definitions for Neoverse-N3. These will be used for errata
detection in subsequent patches.

These values can be found in Table A-261 ("MIDR_EL1 bit descriptions")
in issue 02 of the Neoverse-N3 TRM, which can be found at:

  https://developer.arm.com/documentation/107997/0000/?lang=en

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: James Morse &lt;james.morse@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20240930111705.3352047-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
[ Mark: trivial backport ]
Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 924725707d80bc2588cefafef76ff3f164d299bc ]

Add cputype definitions for Neoverse-N3. These will be used for errata
detection in subsequent patches.

These values can be found in Table A-261 ("MIDR_EL1 bit descriptions")
in issue 02 of the Neoverse-N3 TRM, which can be found at:

  https://developer.arm.com/documentation/107997/0000/?lang=en

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: James Morse &lt;james.morse@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20240930111705.3352047-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
[ Mark: trivial backport ]
Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: Fix kvm_has_feat*() handling of negative features</title>
<updated>2024-10-10T10:03:45+00:00</updated>
<author>
<name>Marc Zyngier</name>
<email>maz@kernel.org</email>
</author>
<published>2024-10-02T20:42:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1e3fc4f2e6d4a50a9e0166c951e1610ec2450001'/>
<id>1e3fc4f2e6d4a50a9e0166c951e1610ec2450001</id>
<content type='text'>
commit a1d402abf8e3ff1d821e88993fc5331784fac0da upstream.

Oliver reports that the kvm_has_feat() helper is not behaviing as
expected for negative feature. On investigation, the main issue
seems to be caused by the following construct:

 #define get_idreg_field(kvm, id, fld)				\
 	(id##_##fld##_SIGNED ?					\
	 get_idreg_field_signed(kvm, id, fld) :			\
	 get_idreg_field_unsigned(kvm, id, fld))

where one side of the expression evaluates as something signed,
and the other as something unsigned. In retrospect, this is totally
braindead, as the compiler converts this into an unsigned expression.
When compared to something that is 0, the test is simply elided.

Epic fail. Similar issue exists in the expand_field_sign() macro.

The correct way to handle this is to chose between signed and unsigned
comparisons, so that both sides of the ternary expression are of the
same type (bool).

In order to keep the code readable (sort of), we introduce new
comparison primitives taking an operator as a parameter, and
rewrite the kvm_has_feat*() helpers in terms of these primitives.

Fixes: c62d7a23b947 ("KVM: arm64: Add feature checking helpers")
Reported-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Tested-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241002204239.2051637-1-maz@kernel.org
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit a1d402abf8e3ff1d821e88993fc5331784fac0da upstream.

Oliver reports that the kvm_has_feat() helper is not behaviing as
expected for negative feature. On investigation, the main issue
seems to be caused by the following construct:

 #define get_idreg_field(kvm, id, fld)				\
 	(id##_##fld##_SIGNED ?					\
	 get_idreg_field_signed(kvm, id, fld) :			\
	 get_idreg_field_unsigned(kvm, id, fld))

where one side of the expression evaluates as something signed,
and the other as something unsigned. In retrospect, this is totally
braindead, as the compiler converts this into an unsigned expression.
When compared to something that is 0, the test is simply elided.

Epic fail. Similar issue exists in the expand_field_sign() macro.

The correct way to handle this is to chose between signed and unsigned
comparisons, so that both sides of the ternary expression are of the
same type (bool).

In order to keep the code readable (sort of), we introduce new
comparison primitives taking an operator as a parameter, and
rewrite the kvm_has_feat*() helpers in terms of these primitives.

Fixes: c62d7a23b947 ("KVM: arm64: Add feature checking helpers")
Reported-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Tested-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241002204239.2051637-1-maz@kernel.org
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: errata: Enable the AC03_CPU_38 workaround for ampere1a</title>
<updated>2024-10-04T14:38:48+00:00</updated>
<author>
<name>D Scott Phillips</name>
<email>scott@os.amperecomputing.com</email>
</author>
<published>2024-08-27T21:17:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=75620914003ed127a3f05cc32f6f8d5c3e980a32'/>
<id>75620914003ed127a3f05cc32f6f8d5c3e980a32</id>
<content type='text'>
commit db0d8a84348b876df7c4276f0cbce5df3b769f5f upstream.

The ampere1a cpu is affected by erratum AC04_CPU_10 which is the same
bug as AC03_CPU_38. Add ampere1a to the AC03_CPU_38 workaround midr list.

Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: D Scott Phillips &lt;scott@os.amperecomputing.com&gt;
Acked-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Link: https://lore.kernel.org/r/20240827211701.2216719-1-scott@os.amperecomputing.com
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit db0d8a84348b876df7c4276f0cbce5df3b769f5f upstream.

The ampere1a cpu is affected by erratum AC04_CPU_10 which is the same
bug as AC03_CPU_38. Add ampere1a to the AC03_CPU_38 workaround midr list.

Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: D Scott Phillips &lt;scott@os.amperecomputing.com&gt;
Acked-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Link: https://lore.kernel.org/r/20240827211701.2216719-1-scott@os.amperecomputing.com
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: esr: Define ESR_ELx_EC_* constants as UL</title>
<updated>2024-10-04T14:38:48+00:00</updated>
<author>
<name>Anastasia Belova</name>
<email>abelova@astralinux.ru</email>
</author>
<published>2024-09-10T08:50:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=783a1429fdd7729e4cea611c4fc309b0ccd2d7a2'/>
<id>783a1429fdd7729e4cea611c4fc309b0ccd2d7a2</id>
<content type='text'>
commit b6db3eb6c373b97d9e433530d748590421bbeea7 upstream.

Add explicit casting to prevent expantion of 32th bit of
u32 into highest half of u64 in several places.

For example, in inject_abt64:
ESR_ELx_EC_DABT_LOW &lt;&lt; ESR_ELx_EC_SHIFT = 0x24 &lt;&lt; 26.
This operation's result is int with 1 in 32th bit.
While casting this value into u64 (esr is u64) 1
fills 32 highest bits.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Cc: &lt;stable@vger.kernel.org&gt;
Fixes: aa8eff9bfbd5 ("arm64: KVM: fault injection into a guest")
Signed-off-by: Anastasia Belova &lt;abelova@astralinux.ru&gt;
Acked-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/stable/20240910085016.32120-1-abelova%40astralinux.ru
Link: https://lore.kernel.org/r/20240910085016.32120-1-abelova@astralinux.ru
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b6db3eb6c373b97d9e433530d748590421bbeea7 upstream.

Add explicit casting to prevent expantion of 32th bit of
u32 into highest half of u64 in several places.

For example, in inject_abt64:
ESR_ELx_EC_DABT_LOW &lt;&lt; ESR_ELx_EC_SHIFT = 0x24 &lt;&lt; 26.
This operation's result is int with 1 in 32th bit.
While casting this value into u64 (esr is u64) 1
fills 32 highest bits.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Cc: &lt;stable@vger.kernel.org&gt;
Fixes: aa8eff9bfbd5 ("arm64: KVM: fault injection into a guest")
Signed-off-by: Anastasia Belova &lt;abelova@astralinux.ru&gt;
Acked-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/stable/20240910085016.32120-1-abelova%40astralinux.ru
Link: https://lore.kernel.org/r/20240910085016.32120-1-abelova@astralinux.ru
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux</title>
<updated>2024-08-17T00:02:32+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-08-17T00:02:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c2cdb13a34d950e61e3b53af0c5f9eb828710beb'/>
<id>c2cdb13a34d950e61e3b53af0c5f9eb828710beb</id>
<content type='text'>
Pull arm64 fixes from Catalin Marinas:

 - Fix the arm64 __get_mem_asm() to use the _ASM_EXTABLE_##type##ACCESS()
   macro instead of the *_ERR() one in order to avoid writing -EFAULT to
   the value register in case of a fault

 - Initialise all elements of the acpi_early_node_map[] to NUMA_NO_NODE.
   Prior to this fix, only the first element was initialised

 - Move the KASAN random tag seed initialisation after the per-CPU areas
   have been initialised (prng_state is __percpu)

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Fix KASAN random tag seed initialization
  arm64: ACPI: NUMA: initialize all values of acpi_early_node_map to NUMA_NO_NODE
  arm64: uaccess: correct thinko in __get_mem_asm()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull arm64 fixes from Catalin Marinas:

 - Fix the arm64 __get_mem_asm() to use the _ASM_EXTABLE_##type##ACCESS()
   macro instead of the *_ERR() one in order to avoid writing -EFAULT to
   the value register in case of a fault

 - Initialise all elements of the acpi_early_node_map[] to NUMA_NO_NODE.
   Prior to this fix, only the first element was initialised

 - Move the KASAN random tag seed initialisation after the per-CPU areas
   have been initialised (prng_state is __percpu)

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Fix KASAN random tag seed initialization
  arm64: ACPI: NUMA: initialize all values of acpi_early_node_map to NUMA_NO_NODE
  arm64: uaccess: correct thinko in __get_mem_asm()
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: uaccess: correct thinko in __get_mem_asm()</title>
<updated>2024-08-14T16:51:11+00:00</updated>
<author>
<name>Mark Rutland</name>
<email>mark.rutland@arm.com</email>
</author>
<published>2024-08-07T10:37:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f94511df53bb792e505c98662971434c7995388a'/>
<id>f94511df53bb792e505c98662971434c7995388a</id>
<content type='text'>
In the CONFIG_CC_HAS_ASM_GOTO_OUTPUT=y version of __get_mem_asm(), we
incorrectly use _ASM_EXTABLE_##type##ACCESS_ERR() such that upon a fault
the extable fixup handler writes -EFAULT into "%w0", which is the
register containing 'x' (the result of the load).

This was a thinko in commit:

  86a6a68febfcf57b ("arm64: start using 'asm goto' for get_user() when available")

Prior to that commit _ASM_EXTABLE_##type##ACCESS_ERR_ZERO() was used
such that the extable fixup handler wrote -EFAULT into "%w0" (the
register containing 'err'), and zero into "%w1" (the register containing
'x'). When the 'err' variable was removed, the extable entry was updated
incorrectly.

Writing -EFAULT to the value register is unnecessary but benign:

* We never want -EFAULT in the value register, and previously this would
  have been zeroed in the extable fixup handler.

* In __get_user_error() the value is overwritten with zero explicitly in
  the error path.

* The asm goto outputs cannot be used when the goto label is taken, as
  older compilers (e.g. clang &lt; 16.0.0) do not guarantee that asm goto
  outputs are usable in this path and may use a stale value rather than
  the value in an output register. Consequently, zeroing in the extable
  fixup handler is insufficient to ensure callers see zero in the error
  path.

* The expected usage of unsafe_get_user() and get_kernel_nofault()
  requires that the value is not consumed in the error path.

Some versions of GCC would mis-compile asm goto with outputs, and
erroneously omit subsequent assignments, breaking the error path
handling in __get_user_error(). This was discussed at:

  https://lore.kernel.org/lkml/ZpfxLrJAOF2YNqCk@J2N7QTR9R3.cambridge.arm.com/

... and was fixed by removing support for asm goto with outputs on those
broken compilers in commit:

  f2f6a8e887172503 ("init/Kconfig: remove CONFIG_GCC_ASM_GOTO_OUTPUT_WORKAROUND")

With that out of the way, we can safely replace the usage of
_ASM_EXTABLE_##type##ACCESS_ERR() with _ASM_EXTABLE_##type##ACCESS(),
leaving the value register unchanged in the case a fault is taken, as
was originally intended. This matches other architectures and matches
our __put_mem_asm().

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20240807103731.2498893-1-mark.rutland@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In the CONFIG_CC_HAS_ASM_GOTO_OUTPUT=y version of __get_mem_asm(), we
incorrectly use _ASM_EXTABLE_##type##ACCESS_ERR() such that upon a fault
the extable fixup handler writes -EFAULT into "%w0", which is the
register containing 'x' (the result of the load).

This was a thinko in commit:

  86a6a68febfcf57b ("arm64: start using 'asm goto' for get_user() when available")

Prior to that commit _ASM_EXTABLE_##type##ACCESS_ERR_ZERO() was used
such that the extable fixup handler wrote -EFAULT into "%w0" (the
register containing 'err'), and zero into "%w1" (the register containing
'x'). When the 'err' variable was removed, the extable entry was updated
incorrectly.

Writing -EFAULT to the value register is unnecessary but benign:

* We never want -EFAULT in the value register, and previously this would
  have been zeroed in the extable fixup handler.

* In __get_user_error() the value is overwritten with zero explicitly in
  the error path.

* The asm goto outputs cannot be used when the goto label is taken, as
  older compilers (e.g. clang &lt; 16.0.0) do not guarantee that asm goto
  outputs are usable in this path and may use a stale value rather than
  the value in an output register. Consequently, zeroing in the extable
  fixup handler is insufficient to ensure callers see zero in the error
  path.

* The expected usage of unsafe_get_user() and get_kernel_nofault()
  requires that the value is not consumed in the error path.

Some versions of GCC would mis-compile asm goto with outputs, and
erroneously omit subsequent assignments, breaking the error path
handling in __get_user_error(). This was discussed at:

  https://lore.kernel.org/lkml/ZpfxLrJAOF2YNqCk@J2N7QTR9R3.cambridge.arm.com/

... and was fixed by removing support for asm goto with outputs on those
broken compilers in commit:

  f2f6a8e887172503 ("init/Kconfig: remove CONFIG_GCC_ASM_GOTO_OUTPUT_WORKAROUND")

With that out of the way, we can safely replace the usage of
_ASM_EXTABLE_##type##ACCESS_ERR() with _ASM_EXTABLE_##type##ACCESS(),
leaving the value register unchanged in the case a fault is taken, as
was originally intended. This matches other architectures and matches
our __put_mem_asm().

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20240807103731.2498893-1-mark.rutland@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
