<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm64, branch v5.2-rc2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2019-05-26T20:45:15+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-05-26T20:45:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=862f0a3227b337cea11d0488b0345dc2670fc297'/>
<id>862f0a3227b337cea11d0488b0345dc2670fc297</id>
<content type='text'>
Pull KVM fixes from Paolo Bonzini:
 "The usual smattering of fixes and tunings that came in too late for
  the merge window, but should not wait four months before they appear
  in a release.

  I also travelled a bit more than usual in the first part of May, which
  didn't help with picking up patches and reports promptly"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (33 commits)
  KVM: x86: fix return value for reserved EFER
  tools/kvm_stat: fix fields filter for child events
  KVM: selftests: Wrap vcpu_nested_state_get/set functions with x86 guard
  kvm: selftests: aarch64: compile with warnings on
  kvm: selftests: aarch64: fix default vm mode
  kvm: selftests: aarch64: dirty_log_test: fix unaligned memslot size
  KVM: s390: fix memory slot handling for KVM_SET_USER_MEMORY_REGION
  KVM: x86/pmu: do not mask the value that is written to fixed PMUs
  KVM: x86/pmu: mask the result of rdpmc according to the width of the counters
  x86/kvm/pmu: Set AMD's virt PMU version to 1
  KVM: x86: do not spam dmesg with VMCS/VMCB dumps
  kvm: Check irqchip mode before assign irqfd
  kvm: svm/avic: fix off-by-one in checking host APIC ID
  KVM: selftests: do not blindly clobber registers in guest asm
  KVM: selftests: Remove duplicated TEST_ASSERT in hyperv_cpuid.c
  KVM: LAPIC: Expose per-vCPU timer_advance_ns to userspace
  KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow
  kvm: vmx: Fix -Wmissing-prototypes warnings
  KVM: nVMX: Fix using __this_cpu_read() in preemptible context
  kvm: fix compilation on s390
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull KVM fixes from Paolo Bonzini:
 "The usual smattering of fixes and tunings that came in too late for
  the merge window, but should not wait four months before they appear
  in a release.

  I also travelled a bit more than usual in the first part of May, which
  didn't help with picking up patches and reports promptly"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (33 commits)
  KVM: x86: fix return value for reserved EFER
  tools/kvm_stat: fix fields filter for child events
  KVM: selftests: Wrap vcpu_nested_state_get/set functions with x86 guard
  kvm: selftests: aarch64: compile with warnings on
  kvm: selftests: aarch64: fix default vm mode
  kvm: selftests: aarch64: dirty_log_test: fix unaligned memslot size
  KVM: s390: fix memory slot handling for KVM_SET_USER_MEMORY_REGION
  KVM: x86/pmu: do not mask the value that is written to fixed PMUs
  KVM: x86/pmu: mask the result of rdpmc according to the width of the counters
  x86/kvm/pmu: Set AMD's virt PMU version to 1
  KVM: x86: do not spam dmesg with VMCS/VMCB dumps
  kvm: Check irqchip mode before assign irqfd
  kvm: svm/avic: fix off-by-one in checking host APIC ID
  KVM: selftests: do not blindly clobber registers in guest asm
  KVM: selftests: Remove duplicated TEST_ASSERT in hyperv_cpuid.c
  KVM: LAPIC: Expose per-vCPU timer_advance_ns to userspace
  KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow
  kvm: vmx: Fix -Wmissing-prototypes warnings
  KVM: nVMX: Fix using __this_cpu_read() in preemptible context
  kvm: fix compilation on s390
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux</title>
<updated>2019-05-24T18:03:26+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-05-24T18:03:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0a72ef89901409847036664c23ba6eee7cf08e0e'/>
<id>0a72ef89901409847036664c23ba6eee7cf08e0e</id>
<content type='text'>
Pull more arm64 fixes from Will Deacon:

 - Fix incorrect LDADD instruction encoding in our disassembly macros

 - Disable the broken ARM64_PSEUDO_NMI support for now

 - Add workaround for Cortex-A76 CPU erratum #1463225

 - Handle Cortex-A76/Neoverse-N1 erratum #1418040 w/ existing workaround

 - Fix IORT build failure if IOMMU_SUPPORT=n

 - Fix place-relative module relocation range checking and its
   interaction with KASLR

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: insn: Add BUILD_BUG_ON() for invalid masks
  arm64: insn: Fix ldadd instruction encoding
  arm64: Kconfig: Make ARM64_PSEUDO_NMI depend on BROKEN for now
  arm64: Handle erratum 1418040 as a superset of erratum 1188873
  arm64/module: deal with ambiguity in PRELxx relocation ranges
  ACPI/IORT: Fix build error when IOMMU_SUPPORT is disabled
  arm64/kernel: kaslr: reduce module randomization range to 2 GB
  arm64: errata: Add workaround for Cortex-A76 erratum #1463225
  arm64: Remove useless message during oops
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull more arm64 fixes from Will Deacon:

 - Fix incorrect LDADD instruction encoding in our disassembly macros

 - Disable the broken ARM64_PSEUDO_NMI support for now

 - Add workaround for Cortex-A76 CPU erratum #1463225

 - Handle Cortex-A76/Neoverse-N1 erratum #1418040 w/ existing workaround

 - Fix IORT build failure if IOMMU_SUPPORT=n

 - Fix place-relative module relocation range checking and its
   interaction with KASLR

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: insn: Add BUILD_BUG_ON() for invalid masks
  arm64: insn: Fix ldadd instruction encoding
  arm64: Kconfig: Make ARM64_PSEUDO_NMI depend on BROKEN for now
  arm64: Handle erratum 1418040 as a superset of erratum 1188873
  arm64/module: deal with ambiguity in PRELxx relocation ranges
  ACPI/IORT: Fix build error when IOMMU_SUPPORT is disabled
  arm64/kernel: kaslr: reduce module randomization range to 2 GB
  arm64: errata: Add workaround for Cortex-A76 erratum #1463225
  arm64: Remove useless message during oops
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: insn: Add BUILD_BUG_ON() for invalid masks</title>
<updated>2019-05-24T13:58:30+00:00</updated>
<author>
<name>Jean-Philippe Brucker</name>
<email>jean-philippe.brucker@arm.com</email>
</author>
<published>2019-05-24T12:52:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=edbcf50eb8aea5f81ae6d83bb969cb0bc02805a1'/>
<id>edbcf50eb8aea5f81ae6d83bb969cb0bc02805a1</id>
<content type='text'>
Detect invalid instruction masks at build time. Some versions of GCC can
warn about the situation, but not all of them, it seems.

Suggested-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe.brucker@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Detect invalid instruction masks at build time. Some versions of GCC can
warn about the situation, but not all of them, it seems.

Suggested-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe.brucker@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: insn: Fix ldadd instruction encoding</title>
<updated>2019-05-24T13:58:29+00:00</updated>
<author>
<name>Jean-Philippe Brucker</name>
<email>jean-philippe.brucker@arm.com</email>
</author>
<published>2019-05-24T12:52:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c5e2edeb01ae9ffbdde95bdcdb6d3614ba1eb195'/>
<id>c5e2edeb01ae9ffbdde95bdcdb6d3614ba1eb195</id>
<content type='text'>
GCC 8.1.0 reports that the ldadd instruction encoding, recently added to
insn.c, doesn't match the mask and couldn't possibly be identified:

 linux/arch/arm64/include/asm/insn.h: In function 'aarch64_insn_is_ldadd':
 linux/arch/arm64/include/asm/insn.h:280:257: warning: bitwise comparison always evaluates to false [-Wtautological-compare]

Bits [31:30] normally encode the size of the instruction (1 to 8 bytes)
and the current instruction value only encodes the 4- and 8-byte
variants. At the moment only the BPF JIT needs this instruction, and
doesn't require the 1- and 2-byte variants, but to be consistent with
our other ldr and str instruction encodings, clear the size field in the
insn value.

Fixes: 34b8ab091f9ef57a ("bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd")
Acked-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reported-by: Kuninori Morimoto &lt;kuninori.morimoto.gx@renesas.com&gt;
Signed-off-by: Yoshihiro Shimoda &lt;yoshihiro.shimoda.uh@renesas.com&gt;
Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe.brucker@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
GCC 8.1.0 reports that the ldadd instruction encoding, recently added to
insn.c, doesn't match the mask and couldn't possibly be identified:

 linux/arch/arm64/include/asm/insn.h: In function 'aarch64_insn_is_ldadd':
 linux/arch/arm64/include/asm/insn.h:280:257: warning: bitwise comparison always evaluates to false [-Wtautological-compare]

Bits [31:30] normally encode the size of the instruction (1 to 8 bytes)
and the current instruction value only encodes the 4- and 8-byte
variants. At the moment only the BPF JIT needs this instruction, and
doesn't require the 1- and 2-byte variants, but to be consistent with
our other ldr and str instruction encodings, clear the size field in the
insn value.

Fixes: 34b8ab091f9ef57a ("bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd")
Acked-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reported-by: Kuninori Morimoto &lt;kuninori.morimoto.gx@renesas.com&gt;
Signed-off-by: Yoshihiro Shimoda &lt;yoshihiro.shimoda.uh@renesas.com&gt;
Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe.brucker@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: Kconfig: Make ARM64_PSEUDO_NMI depend on BROKEN for now</title>
<updated>2019-05-24T13:58:19+00:00</updated>
<author>
<name>Will Deacon</name>
<email>will.deacon@arm.com</email>
</author>
<published>2019-05-24T13:15:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=96a13f57b946be7a6c10405e4bd780c0b6b6fe63'/>
<id>96a13f57b946be7a6c10405e4bd780c0b6b6fe63</id>
<content type='text'>
Although we merged support for pseudo-nmi using interrupt priority
masking in 5.1, we've since uncovered a number of non-trivial issues
with the implementation. Although there are patches pending to address
these problems, we're facing issues that prevent us from merging them at
this current time:

  https://lkml.kernel.org/r/1556553607-46531-1-git-send-email-julien.thierry@arm.com

For now, simply mark this optional feature as BROKEN in the hope that we
can fix things properly in the near future.

Cc: &lt;stable@vger.kernel.org&gt; # 5.1
Cc: Julien Thierry &lt;julien.thierry@arm.com&gt;
Acked-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Although we merged support for pseudo-nmi using interrupt priority
masking in 5.1, we've since uncovered a number of non-trivial issues
with the implementation. Although there are patches pending to address
these problems, we're facing issues that prevent us from merging them at
this current time:

  https://lkml.kernel.org/r/1556553607-46531-1-git-send-email-julien.thierry@arm.com

For now, simply mark this optional feature as BROKEN in the hope that we
can fix things properly in the near future.

Cc: &lt;stable@vger.kernel.org&gt; # 5.1
Cc: Julien Thierry &lt;julien.thierry@arm.com&gt;
Acked-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm/arm64: Move cc/it checks under hyp's Makefile to avoid instrumentation</title>
<updated>2019-05-24T13:53:20+00:00</updated>
<author>
<name>James Morse</name>
<email>james.morse@arm.com</email>
</author>
<published>2019-05-22T17:47:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=623e1528d4090bd1abaf93ec46f047dee9a6fb32'/>
<id>623e1528d4090bd1abaf93ec46f047dee9a6fb32</id>
<content type='text'>
KVM has helpers to handle the condition codes of trapped aarch32
instructions. These are marked __hyp_text and used from HYP, but they
aren't built by the 'hyp' Makefile, which has all the runes to avoid ASAN
and KCOV instrumentation.

Move this code to a new hyp/aarch32.c to avoid a hyp-panic when starting
an aarch32 guest on a host built with the ASAN/KCOV debug options.

Fixes: 021234ef3752f ("KVM: arm64: Make kvm_condition_valid32() accessible from EL2")
Fixes: 8cebe750c4d9a ("arm64: KVM: Make kvm_skip_instr32 available to HYP")
Signed-off-by: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM has helpers to handle the condition codes of trapped aarch32
instructions. These are marked __hyp_text and used from HYP, but they
aren't built by the 'hyp' Makefile, which has all the runes to avoid ASAN
and KCOV instrumentation.

Move this code to a new hyp/aarch32.c to avoid a hyp-panic when starting
an aarch32 guest on a host built with the ASAN/KCOV debug options.

Fixes: 021234ef3752f ("KVM: arm64: Make kvm_condition_valid32() accessible from EL2")
Fixes: 8cebe750c4d9a ("arm64: KVM: Make kvm_skip_instr32 available to HYP")
Signed-off-by: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: Move pmu hyp code under hyp's Makefile to avoid instrumentation</title>
<updated>2019-05-24T13:53:20+00:00</updated>
<author>
<name>James Morse</name>
<email>james.morse@arm.com</email>
</author>
<published>2019-05-22T17:47:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b7c50fab66ab66e2d3e00f809a09578d78232836'/>
<id>b7c50fab66ab66e2d3e00f809a09578d78232836</id>
<content type='text'>
KVM's pmu.c contains the __hyp_text needed to switch the pmu registers
between host and guest. Because this isn't covered by the 'hyp' Makefile,
it can be built with kasan and friends when these are enabled in Kconfig.

When starting a guest, this results in:
| Kernel panic - not syncing: HYP panic:
| PS:a00003c9 PC:000083000028ada0 ESR:86000007
| FAR:000083000028ada0 HPFAR:0000000029df5300 PAR:0000000000000000
| VCPU:000000004e10b7d6
| CPU: 0 PID: 3088 Comm: qemu-system-aar Not tainted 5.2.0-rc1 #11026
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Plat
| Call trace:
|  dump_backtrace+0x0/0x200
|  show_stack+0x20/0x30
|  dump_stack+0xec/0x158
|  panic+0x1ec/0x420
|  panic+0x0/0x420
| SMP: stopping secondary CPUs
| Kernel Offset: disabled
| CPU features: 0x002,25006082
| Memory Limit: none
| ---[ end Kernel panic - not syncing: HYP panic:

This is caused by functions in pmu.c calling the instrumented
code, which isn't mapped to hyp. From objdump -r:
| RELOCATION RECORDS FOR [.hyp.text]:
| OFFSET           TYPE              VALUE
| 0000000000000010 R_AARCH64_CALL26  __sanitizer_cov_trace_pc
| 0000000000000018 R_AARCH64_CALL26  __asan_load4_noabort
| 0000000000000024 R_AARCH64_CALL26  __asan_load4_noabort

Move the affected code to a new file under 'hyp's Makefile.

Fixes: 3d91befbb3a0 ("arm64: KVM: Enable !VHE support for :G/:H perf event modifiers")
Cc: Andrew Murray &lt;Andrew.Murray@arm.com&gt;
Signed-off-by: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM's pmu.c contains the __hyp_text needed to switch the pmu registers
between host and guest. Because this isn't covered by the 'hyp' Makefile,
it can be built with kasan and friends when these are enabled in Kconfig.

When starting a guest, this results in:
| Kernel panic - not syncing: HYP panic:
| PS:a00003c9 PC:000083000028ada0 ESR:86000007
| FAR:000083000028ada0 HPFAR:0000000029df5300 PAR:0000000000000000
| VCPU:000000004e10b7d6
| CPU: 0 PID: 3088 Comm: qemu-system-aar Not tainted 5.2.0-rc1 #11026
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Plat
| Call trace:
|  dump_backtrace+0x0/0x200
|  show_stack+0x20/0x30
|  dump_stack+0xec/0x158
|  panic+0x1ec/0x420
|  panic+0x0/0x420
| SMP: stopping secondary CPUs
| Kernel Offset: disabled
| CPU features: 0x002,25006082
| Memory Limit: none
| ---[ end Kernel panic - not syncing: HYP panic:

This is caused by functions in pmu.c calling the instrumented
code, which isn't mapped to hyp. From objdump -r:
| RELOCATION RECORDS FOR [.hyp.text]:
| OFFSET           TYPE              VALUE
| 0000000000000010 R_AARCH64_CALL26  __sanitizer_cov_trace_pc
| 0000000000000018 R_AARCH64_CALL26  __asan_load4_noabort
| 0000000000000024 R_AARCH64_CALL26  __asan_load4_noabort

Move the affected code to a new file under 'hyp's Makefile.

Fixes: 3d91befbb3a0 ("arm64: KVM: Enable !VHE support for :G/:H perf event modifiers")
Cc: Andrew Murray &lt;Andrew.Murray@arm.com&gt;
Signed-off-by: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: Handle erratum 1418040 as a superset of erratum 1188873</title>
<updated>2019-05-23T14:40:30+00:00</updated>
<author>
<name>Marc Zyngier</name>
<email>marc.zyngier@arm.com</email>
</author>
<published>2019-05-23T10:24:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a5325089bd05a7b0259cc4038479d36308edbda2'/>
<id>a5325089bd05a7b0259cc4038479d36308edbda2</id>
<content type='text'>
We already mitigate erratum 1188873 affecting Cortex-A76 and
Neoverse-N1 r0p0 to r2p0. It turns out that revisions r0p0 to
r3p1 of the same cores are affected by erratum 1418040, which
has the same workaround as 1188873.

Let's expand the range of affected revisions to match 1418040,
and repaint all occurences of 1188873 to 1418040. Whilst we're
there, do a bit of reformating in silicon-errata.txt and drop
a now unnecessary dependency on ARM_ARCH_TIMER_OOL_WORKAROUND.

Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We already mitigate erratum 1188873 affecting Cortex-A76 and
Neoverse-N1 r0p0 to r2p0. It turns out that revisions r0p0 to
r3p1 of the same cores are affected by erratum 1418040, which
has the same workaround as 1188873.

Let's expand the range of affected revisions to match 1418040,
and repaint all occurences of 1188873 to 1418040. Whilst we're
there, do a bit of reformating in silicon-errata.txt and drop
a now unnecessary dependency on ARM_ARCH_TIMER_OOL_WORKAROUND.

Signed-off-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64/module: deal with ambiguity in PRELxx relocation ranges</title>
<updated>2019-05-23T14:34:04+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ard.biesheuvel@linaro.org</email>
</author>
<published>2019-05-23T10:38:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1cf24a2cc3fd40942b0f9e6199aaec579e89a832'/>
<id>1cf24a2cc3fd40942b0f9e6199aaec579e89a832</id>
<content type='text'>
The R_AARCH64_PREL16 and R_AARCH64_PREL32 relocations are
documented as permitting a range of [-2^15 .. 2^16), resp.
[-2^31 .. 2^32). It is also documented that this means we
cannot detect overflow in some cases, which is bad.

Since we always interpret the targets of these relocations as
signed quantities (e.g., in the ksymtab handling code), let's
tighten the overflow checks so that targets that are out of
range for our signed interpretation of the relocated quantity
get flagged.

Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The R_AARCH64_PREL16 and R_AARCH64_PREL32 relocations are
documented as permitting a range of [-2^15 .. 2^16), resp.
[-2^31 .. 2^32). It is also documented that this means we
cannot detect overflow in some cases, which is bad.

Since we always interpret the targets of these relocations as
signed quantities (e.g., in the ksymtab handling code), let's
tighten the overflow checks so that targets that are out of
range for our signed interpretation of the relocated quantity
get flagged.

Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64/kernel: kaslr: reduce module randomization range to 2 GB</title>
<updated>2019-05-23T10:38:11+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ard.biesheuvel@arm.com</email>
</author>
<published>2019-05-23T09:17:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b2eed9b58811283d00fa861944cb75797d4e52a7'/>
<id>b2eed9b58811283d00fa861944cb75797d4e52a7</id>
<content type='text'>
The following commit

  7290d5809571 ("module: use relative references for __ksymtab entries")

updated the ksymtab handling of some KASLR capable architectures
so that ksymtab entries are emitted as pairs of 32-bit relative
references. This reduces the size of the entries, but more
importantly, it gets rid of statically assigned absolute
addresses, which require fixing up at boot time if the kernel
is self relocating (which takes a 24 byte RELA entry for each
member of the ksymtab struct).

Since ksymtab entries are always part of the same module as the
symbol they export, it was assumed at the time that a 32-bit
relative reference is always sufficient to capture the offset
between a ksymtab entry and its target symbol.

Unfortunately, this is not always true: in the case of per-CPU
variables, a per-CPU variable's base address (which usually differs
from the actual address of any of its per-CPU copies) is allocated
in the vicinity of the ..data.percpu section in the core kernel
(i.e., in the per-CPU reserved region which follows the section
containing the core kernel's statically allocated per-CPU variables).

Since we randomize the module space over a 4 GB window covering
the core kernel (based on the -/+ 4 GB range of an ADRP/ADD pair),
we may end up putting the core kernel out of the -/+ 2 GB range of
32-bit relative references of module ksymtab entries that refer to
per-CPU variables.

So reduce the module randomization range a bit further. We lose
1 bit of randomization this way, but this is something we can
tolerate.

Cc: &lt;stable@vger.kernel.org&gt; # v4.19+
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The following commit

  7290d5809571 ("module: use relative references for __ksymtab entries")

updated the ksymtab handling of some KASLR capable architectures
so that ksymtab entries are emitted as pairs of 32-bit relative
references. This reduces the size of the entries, but more
importantly, it gets rid of statically assigned absolute
addresses, which require fixing up at boot time if the kernel
is self relocating (which takes a 24 byte RELA entry for each
member of the ksymtab struct).

Since ksymtab entries are always part of the same module as the
symbol they export, it was assumed at the time that a 32-bit
relative reference is always sufficient to capture the offset
between a ksymtab entry and its target symbol.

Unfortunately, this is not always true: in the case of per-CPU
variables, a per-CPU variable's base address (which usually differs
from the actual address of any of its per-CPU copies) is allocated
in the vicinity of the ..data.percpu section in the core kernel
(i.e., in the per-CPU reserved region which follows the section
containing the core kernel's statically allocated per-CPU variables).

Since we randomize the module space over a 4 GB window covering
the core kernel (based on the -/+ 4 GB range of an ADRP/ADD pair),
we may end up putting the core kernel out of the -/+ 2 GB range of
32-bit relative references of module ksymtab entries that refer to
per-CPU variables.

So reduce the module randomization range a bit further. We lose
1 bit of randomization this way, but this is something we can
tolerate.

Cc: &lt;stable@vger.kernel.org&gt; # v4.19+
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
