<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm64/include, branch v6.1.2</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>arm64: make is_ttbrX_addr() noinstr-safe</title>
<updated>2022-12-31T12:32:56+00:00</updated>
<author>
<name>Mark Rutland</name>
<email>mark.rutland@arm.com</email>
</author>
<published>2022-11-14T14:40:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=992469fb6ca0c7edf9dbf4af5cbba4b62358eea5'/>
<id>992469fb6ca0c7edf9dbf4af5cbba4b62358eea5</id>
<content type='text'>
[ Upstream commit d8c1d798a2e5091128c391c6dadcc9be334af3f5 ]

We use is_ttbr0_addr() in noinstr code, but as it's only marked as
inline, it's theoretically possible for the compiler to place it
out-of-line and instrument it, which would be problematic.

Mark is_ttbr0_addr() as __always_inline such that that can safely be
used from noinstr code. For consistency, do the same to is_ttbr1_addr().
Note that while is_ttbr1_addr() calls arch_kasan_reset_tag(), this is a
macro (and its callees are either macros or __always_inline), so there
is not a risk of transient instrumentation.

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/20221114144042.3001140-1-mark.rutland@arm.com
Signed-off-by: Will Deacon &lt;will@kernel.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 d8c1d798a2e5091128c391c6dadcc9be334af3f5 ]

We use is_ttbr0_addr() in noinstr code, but as it's only marked as
inline, it's theoretically possible for the compiler to place it
out-of-line and instrument it, which would be problematic.

Mark is_ttbr0_addr() as __always_inline such that that can safely be
used from noinstr code. For consistency, do the same to is_ttbr1_addr().
Note that while is_ttbr1_addr() calls arch_kasan_reset_tag(), this is a
macro (and its callees are either macros or __always_inline), so there
is not a risk of transient instrumentation.

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/20221114144042.3001140-1-mark.rutland@arm.com
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'efi-fixes-for-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi</title>
<updated>2022-12-01T19:25:11+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-12-01T19:25:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=355479c70a489415ef6e2624e514f8f15a40861b'/>
<id>355479c70a489415ef6e2624e514f8f15a40861b</id>
<content type='text'>
Pull EFI fix from Ard Biesheuvel:
 "A single revert for some code that I added during this cycle. The code
  is not wrong, but it should be a bit more careful about how to handle
  the shadow call stack pointer, so it is better to revert it for now
  and bring it back later in improved form.

  Summary:

   - Revert runtime service sync exception recovery on arm64"

* tag 'efi-fixes-for-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  arm64: efi: Revert "Recover from synchronous exceptions ..."
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull EFI fix from Ard Biesheuvel:
 "A single revert for some code that I added during this cycle. The code
  is not wrong, but it should be a bit more careful about how to handle
  the shadow call stack pointer, so it is better to revert it for now
  and bring it back later in improved form.

  Summary:

   - Revert runtime service sync exception recovery on arm64"

* tag 'efi-fixes-for-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  arm64: efi: Revert "Recover from synchronous exceptions ..."
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: efi: Revert "Recover from synchronous exceptions ..."</title>
<updated>2022-12-01T13:48:26+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2022-11-30T16:37:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=7572ac3c979d4d0fb42d73a72d2608656516ff4f'/>
<id>7572ac3c979d4d0fb42d73a72d2608656516ff4f</id>
<content type='text'>
This reverts commit 23715a26c8d81291, which introduced some code in
assembler that manipulates both the ordinary and the shadow call stack
pointer in a way that could potentially be taken advantage of. So let's
revert it, and do a better job the next time around.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 23715a26c8d81291, which introduced some code in
assembler that manipulates both the ordinary and the shadow call stack
pointer in a way that could potentially be taken advantage of. So let's
revert it, and do a better job the next time around.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.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>2022-11-18T22:31:03+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-18T22:31:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=23a60a03d9a9980d1e91190491ceea0dc58fae62'/>
<id>23a60a03d9a9980d1e91190491ceea0dc58fae62</id>
<content type='text'>
Pull arm64 fixes from Catalin Marinas:

 - Fix a build error with CONFIG_CFI_CLANG + CONFIG_FTRACE when
   CONFIG_FUNCTION_GRAPH_TRACER is not enabled.

 - Fix a BUG_ON triggered by the page table checker due to incorrect
   file_map_count for non-leaf pmd/pud (the arm64
   pmd_user_accessible_page() not checking whether it's a leaf entry).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
  arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull arm64 fixes from Catalin Marinas:

 - Fix a build error with CONFIG_CFI_CLANG + CONFIG_FTRACE when
   CONFIG_FUNCTION_GRAPH_TRACER is not enabled.

 - Fix a BUG_ON triggered by the page table checker due to incorrect
   file_map_count for non-leaf pmd/pud (the arm64
   pmd_user_accessible_page() not checking whether it's a leaf entry).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
  arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud</title>
<updated>2022-11-18T19:31:54+00:00</updated>
<author>
<name>Liu Shixin</name>
<email>liushixin2@huawei.com</email>
</author>
<published>2022-11-17T07:56:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=5b47348fc0b18a78c96f8474cc90b7525ad1bbfe'/>
<id>5b47348fc0b18a78c96f8474cc90b7525ad1bbfe</id>
<content type='text'>
The page table check trigger BUG_ON() unexpectedly when collapse hugepage:

 ------------[ cut here ]------------
 kernel BUG at mm/page_table_check.c:82!
 Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Modules linked in:
 CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750
 Hardware name: linux,dummy-virt (DT)
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : page_table_check_clear.isra.0+0x258/0x3f0
 lr : page_table_check_clear.isra.0+0x240/0x3f0
[...]
 Call trace:
  page_table_check_clear.isra.0+0x258/0x3f0
  __page_table_check_pmd_clear+0xbc/0x108
  pmdp_collapse_flush+0xb0/0x160
  collapse_huge_page+0xa08/0x1080
  hpage_collapse_scan_pmd+0xf30/0x1590
  khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8
  khugepaged+0x338/0x518
  kthread+0x278/0x2f8
  ret_from_fork+0x10/0x20
[...]

Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it
decrease file_map_count for a non-leaf pmd comes from collapse_huge_page().
and so trigger BUG_ON() unexpectedly.

Fix this problem by using pmd_leaf() insteal of pmd_present() in
pmd_user_accessible_page(). Moreover, use pud_leaf() for
pud_user_accessible_page() too.

Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
Reported-by: Denys Vlasenko &lt;dvlasenk@redhat.com&gt;
Signed-off-by: Liu Shixin &lt;liushixin2@huawei.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Reviewed-by: Kefeng Wang &lt;wangkefeng.wang@huawei.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20221117075602.2904324-2-liushixin2@huawei.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>
The page table check trigger BUG_ON() unexpectedly when collapse hugepage:

 ------------[ cut here ]------------
 kernel BUG at mm/page_table_check.c:82!
 Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Modules linked in:
 CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750
 Hardware name: linux,dummy-virt (DT)
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : page_table_check_clear.isra.0+0x258/0x3f0
 lr : page_table_check_clear.isra.0+0x240/0x3f0
[...]
 Call trace:
  page_table_check_clear.isra.0+0x258/0x3f0
  __page_table_check_pmd_clear+0xbc/0x108
  pmdp_collapse_flush+0xb0/0x160
  collapse_huge_page+0xa08/0x1080
  hpage_collapse_scan_pmd+0xf30/0x1590
  khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8
  khugepaged+0x338/0x518
  kthread+0x278/0x2f8
  ret_from_fork+0x10/0x20
[...]

Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it
decrease file_map_count for a non-leaf pmd comes from collapse_huge_page().
and so trigger BUG_ON() unexpectedly.

Fix this problem by using pmd_leaf() insteal of pmd_present() in
pmd_user_accessible_page(). Moreover, use pud_leaf() for
pud_user_accessible_page() too.

Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
Reported-by: Denys Vlasenko &lt;dvlasenk@redhat.com&gt;
Signed-off-by: Liu Shixin &lt;liushixin2@huawei.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Reviewed-by: Kefeng Wang &lt;wangkefeng.wang@huawei.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20221117075602.2904324-2-liushixin2@huawei.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&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>2022-11-12T01:10:13+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-12T01:10:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=5ad6e7ba98c29d61794a3f216414d8542a3e476c'/>
<id>5ad6e7ba98c29d61794a3f216414d8542a3e476c</id>
<content type='text'>
Pull arm64 fixes from Catalin Marinas:

 - Another fix for rodata=full. Since rodata= is not a simple boolean on
   arm64 (accepting 'full' as well), it got inadvertently broken by
   changes in the core code. If rodata=on is the default and rodata=off
   is passed on the kernel command line, rodata_full is never disabled

 - Fix gcc compiler warning of shifting 0xc0 into bits 31:24 without an
   explicit conversion to u32 (triggered by the AMPERE1 MIDR definition)

 - Include asm/ptrace.h in asm/syscall_wrapper.h to fix an incomplete
   struct pt_regs type causing the BPF verifier to refuse to load a
   tracing program which accesses pt_regs

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/syscall: Include asm/ptrace.h in syscall_wrapper header.
  arm64: Fix bit-shifting UB in the MIDR_CPU_MODEL() macro
  arm64: fix rodata=full again
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull arm64 fixes from Catalin Marinas:

 - Another fix for rodata=full. Since rodata= is not a simple boolean on
   arm64 (accepting 'full' as well), it got inadvertently broken by
   changes in the core code. If rodata=on is the default and rodata=off
   is passed on the kernel command line, rodata_full is never disabled

 - Fix gcc compiler warning of shifting 0xc0 into bits 31:24 without an
   explicit conversion to u32 (triggered by the AMPERE1 MIDR definition)

 - Include asm/ptrace.h in asm/syscall_wrapper.h to fix an incomplete
   struct pt_regs type causing the BPF verifier to refuse to load a
   tracing program which accesses pt_regs

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/syscall: Include asm/ptrace.h in syscall_wrapper header.
  arm64: Fix bit-shifting UB in the MIDR_CPU_MODEL() macro
  arm64: fix rodata=full again
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64/syscall: Include asm/ptrace.h in syscall_wrapper header.</title>
<updated>2022-11-09T09:52:25+00:00</updated>
<author>
<name>Kuniyuki Iwashima</name>
<email>kuniyu@amazon.com</email>
</author>
<published>2022-10-31T21:57:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=acfc35cfcee5df419391671ef1a631f43feee4e3'/>
<id>acfc35cfcee5df419391671ef1a631f43feee4e3</id>
<content type='text'>
Add the same change for ARM64 as done in the commit 9440c4294160
("x86/syscall: Include asm/ptrace.h in syscall_wrapper header") to
make sure all syscalls see 'struct pt_regs' definition and resulted
BTF for '__arm64_sys_*(struct pt_regs *regs)' functions point to
actual struct.

Without this patch, the BPF verifier refuses to load a tracing prog
which accesses pt_regs.

  bpf(BPF_PROG_LOAD, {prog_type=0x1a, ...}, 128) = -1 EACCES

With this patch, we can see the correct error, which saves us time
in debugging the prog.

  bpf(BPF_PROG_LOAD, {prog_type=0x1a, ...}, 128) = 4
  bpf(BPF_RAW_TRACEPOINT_OPEN, {raw_tracepoint={name=NULL, prog_fd=4}}, 128) = -1 ENOTSUPP

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/r/20221031215728.50389-1-kuniyu@amazon.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>
Add the same change for ARM64 as done in the commit 9440c4294160
("x86/syscall: Include asm/ptrace.h in syscall_wrapper header") to
make sure all syscalls see 'struct pt_regs' definition and resulted
BTF for '__arm64_sys_*(struct pt_regs *regs)' functions point to
actual struct.

Without this patch, the BPF verifier refuses to load a tracing prog
which accesses pt_regs.

  bpf(BPF_PROG_LOAD, {prog_type=0x1a, ...}, 128) = -1 EACCES

With this patch, we can see the correct error, which saves us time
in debugging the prog.

  bpf(BPF_PROG_LOAD, {prog_type=0x1a, ...}, 128) = 4
  bpf(BPF_RAW_TRACEPOINT_OPEN, {raw_tracepoint={name=NULL, prog_fd=4}}, 128) = -1 ENOTSUPP

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/r/20221031215728.50389-1-kuniyu@amazon.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: Fix bit-shifting UB in the MIDR_CPU_MODEL() macro</title>
<updated>2022-11-09T09:51:39+00:00</updated>
<author>
<name>D Scott Phillips</name>
<email>scott@os.amperecomputing.com</email>
</author>
<published>2022-11-02T16:01:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=8ec8490a1950efeccb00967698cf7cb2fcd25ca7'/>
<id>8ec8490a1950efeccb00967698cf7cb2fcd25ca7</id>
<content type='text'>
CONFIG_UBSAN_SHIFT with gcc-5 complains that the shifting of
ARM_CPU_IMP_AMPERE (0xC0) into bits [31:24] by MIDR_CPU_MODEL() is
undefined behavior. Well, sort of, it actually spells the error as:

 arch/arm64/kernel/proton-pack.c: In function 'spectre_bhb_loop_affected':
 arch/arm64/include/asm/cputype.h:44:2: error: initializer element is not constant
   (((imp)   &lt;&lt; MIDR_IMPLEMENTOR_SHIFT) | \
   ^

This isn't an issue for other Implementor codes, as all the other codes
have zero in the top bit and so are representable as a signed int.

Cast the implementor code to unsigned in MIDR_CPU_MODEL to remove the
undefined behavior.

Fixes: 0e5d5ae837c8 ("arm64: Add AMPERE1 to the Spectre-BHB affected list")
Reported-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Signed-off-by: D Scott Phillips &lt;scott@os.amperecomputing.com&gt;
Link: https://lore.kernel.org/r/20221102160106.1096948-1-scott@os.amperecomputing.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>
CONFIG_UBSAN_SHIFT with gcc-5 complains that the shifting of
ARM_CPU_IMP_AMPERE (0xC0) into bits [31:24] by MIDR_CPU_MODEL() is
undefined behavior. Well, sort of, it actually spells the error as:

 arch/arm64/kernel/proton-pack.c: In function 'spectre_bhb_loop_affected':
 arch/arm64/include/asm/cputype.h:44:2: error: initializer element is not constant
   (((imp)   &lt;&lt; MIDR_IMPLEMENTOR_SHIFT) | \
   ^

This isn't an issue for other Implementor codes, as all the other codes
have zero in the top bit and so are representable as a signed int.

Cast the implementor code to unsigned in MIDR_CPU_MODEL to remove the
undefined behavior.

Fixes: 0e5d5ae837c8 ("arm64: Add AMPERE1 to the Spectre-BHB affected list")
Reported-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Signed-off-by: D Scott Phillips &lt;scott@os.amperecomputing.com&gt;
Link: https://lore.kernel.org/r/20221102160106.1096948-1-scott@os.amperecomputing.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'efi-fixes-for-v6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi</title>
<updated>2022-11-04T21:37:25+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-04T21:37:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=1caa2f182afb59de9d6d5ba64b340df011a0b653'/>
<id>1caa2f182afb59de9d6d5ba64b340df011a0b653</id>
<content type='text'>
Pull EFI fixes from Ard Biesheuvel:

 - A pair of tweaks to the EFI random seed code so that externally
   provided version of this config table are handled more robustly

 - Another fix for the v6.0 EFI variable refactor that turned out to
   break Apple machines which don't provide QueryVariableInfo()

 - Add some guard rails to the EFI runtime service call wrapper so we
   can recover from synchronous exceptions caused by firmware

* tag 'efi-fixes-for-v6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  arm64: efi: Recover from synchronous exceptions occurring in firmware
  efi: efivars: Fix variable writes with unsupported query_variable_store()
  efi: random: Use 'ACPI reclaim' memory for random seed
  efi: random: reduce seed size to 32 bytes
  efi/tpm: Pass correct address to memblock_reserve
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull EFI fixes from Ard Biesheuvel:

 - A pair of tweaks to the EFI random seed code so that externally
   provided version of this config table are handled more robustly

 - Another fix for the v6.0 EFI variable refactor that turned out to
   break Apple machines which don't provide QueryVariableInfo()

 - Add some guard rails to the EFI runtime service call wrapper so we
   can recover from synchronous exceptions caused by firmware

* tag 'efi-fixes-for-v6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  arm64: efi: Recover from synchronous exceptions occurring in firmware
  efi: efivars: Fix variable writes with unsupported query_variable_store()
  efi: random: Use 'ACPI reclaim' memory for random seed
  efi: random: reduce seed size to 32 bytes
  efi/tpm: Pass correct address to memblock_reserve
</pre>
</div>
</content>
</entry>
<entry>
<title>arm64: efi: Recover from synchronous exceptions occurring in firmware</title>
<updated>2022-11-03T17:01:15+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2022-10-28T14:39:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=23715a26c8d812912a70c6ac1ce67af649b95914'/>
<id>23715a26c8d812912a70c6ac1ce67af649b95914</id>
<content type='text'>
Unlike x86, which has machinery to deal with page faults that occur
during the execution of EFI runtime services, arm64 has nothing like
that, and a synchronous exception raised by firmware code brings down
the whole system.

With more EFI based systems appearing that were not built to run Linux
(such as the Windows-on-ARM laptops based on Qualcomm SOCs), as well as
the introduction of PRM (platform specific firmware routines that are
callable just like EFI runtime services), we are more likely to run into
issues of this sort, and it is much more likely that we can identify and
work around such issues if they don't bring down the system entirely.

Since we already use a EFI runtime services call wrapper in assembler,
we can quite easily add some code that captures the execution state at
the point where the call is made, allowing us to revert to this state
and proceed execution if the call triggered a synchronous exception.

Given that the kernel and the firmware don't share any data structures
that could end up in an indeterminate state, we can happily continue
running, as long as we mark the EFI runtime services as unavailable from
that point on.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Acked-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Unlike x86, which has machinery to deal with page faults that occur
during the execution of EFI runtime services, arm64 has nothing like
that, and a synchronous exception raised by firmware code brings down
the whole system.

With more EFI based systems appearing that were not built to run Linux
(such as the Windows-on-ARM laptops based on Qualcomm SOCs), as well as
the introduction of PRM (platform specific firmware routines that are
callable just like EFI runtime services), we are more likely to run into
issues of this sort, and it is much more likely that we can identify and
work around such issues if they don't bring down the system entirely.

Since we already use a EFI runtime services call wrapper in assembler,
we can quite easily add some code that captures the execution state at
the point where the call is made, allowing us to revert to this state
and proceed execution if the call triggered a synchronous exception.

Given that the kernel and the firmware don't share any data structures
that could end up in an indeterminate state, we can happily continue
running, as long as we mark the EFI runtime services as unavailable from
that point on.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Acked-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
