<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm/include, branch v4.19.205</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>KVM: arm64: Initialize VCPU mdcr_el2 before loading it</title>
<updated>2021-05-22T08:59:50+00:00</updated>
<author>
<name>Alexandru Elisei</name>
<email>alexandru.elisei@arm.com</email>
</author>
<published>2021-04-07T14:48:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=9e43d5e4f8a30bff5a6d08848dd362d60f8775d7'/>
<id>9e43d5e4f8a30bff5a6d08848dd362d60f8775d7</id>
<content type='text'>
commit 263d6287da1433aba11c5b4046388f2cdf49675c upstream.

When a VCPU is created, the kvm_vcpu struct is initialized to zero in
kvm_vm_ioctl_create_vcpu(). On VHE systems, the first time
vcpu.arch.mdcr_el2 is loaded on hardware is in vcpu_load(), before it is
set to a sensible value in kvm_arm_setup_debug() later in the run loop. The
result is that KVM executes for a short time with MDCR_EL2 set to zero.

This has several unintended consequences:

* Setting MDCR_EL2.HPMN to 0 is constrained unpredictable according to ARM
  DDI 0487G.a, page D13-3820. The behavior specified by the architecture
  in this case is for the PE to behave as if MDCR_EL2.HPMN is set to a
  value less than or equal to PMCR_EL0.N, which means that an unknown
  number of counters are now disabled by MDCR_EL2.HPME, which is zero.

* The host configuration for the other debug features controlled by
  MDCR_EL2 is temporarily lost. This has been harmless so far, as Linux
  doesn't use the other fields, but that might change in the future.

Let's avoid both issues by initializing the VCPU's mdcr_el2 field in
kvm_vcpu_vcpu_first_run_init(), thus making sure that the MDCR_EL2 register
has a consistent value after each vcpu_load().

Fixes: d5a21bcc2995 ("KVM: arm64: Move common VHE/non-VHE trap config in separate functions")
Signed-off-by: Alexandru Elisei &lt;alexandru.elisei@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20210407144857.199746-3-alexandru.elisei@arm.com
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 263d6287da1433aba11c5b4046388f2cdf49675c upstream.

When a VCPU is created, the kvm_vcpu struct is initialized to zero in
kvm_vm_ioctl_create_vcpu(). On VHE systems, the first time
vcpu.arch.mdcr_el2 is loaded on hardware is in vcpu_load(), before it is
set to a sensible value in kvm_arm_setup_debug() later in the run loop. The
result is that KVM executes for a short time with MDCR_EL2 set to zero.

This has several unintended consequences:

* Setting MDCR_EL2.HPMN to 0 is constrained unpredictable according to ARM
  DDI 0487G.a, page D13-3820. The behavior specified by the architecture
  in this case is for the PE to behave as if MDCR_EL2.HPMN is set to a
  value less than or equal to PMCR_EL0.N, which means that an unknown
  number of counters are now disabled by MDCR_EL2.HPME, which is zero.

* The host configuration for the other debug features controlled by
  MDCR_EL2 is temporarily lost. This has been harmless so far, as Linux
  doesn't use the other fields, but that might change in the future.

Let's avoid both issues by initializing the VCPU's mdcr_el2 field in
kvm_vcpu_vcpu_first_run_init(), thus making sure that the MDCR_EL2 register
has a consistent value after each vcpu_load().

Fixes: d5a21bcc2995 ("KVM: arm64: Move common VHE/non-VHE trap config in separate functions")
Signed-off-by: Alexandru Elisei &lt;alexandru.elisei@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20210407144857.199746-3-alexandru.elisei@arm.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: kexec: fix oops after TLB are invalidated</title>
<updated>2021-02-23T14:00:57+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@armlinux.org.uk</email>
</author>
<published>2021-02-01T19:40:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=196d7e7c02edbd72c932f6e39c7ec948d0045f77'/>
<id>196d7e7c02edbd72c932f6e39c7ec948d0045f77</id>
<content type='text'>
[ Upstream commit 4d62e81b60d4025e2dfcd5ea531cc1394ce9226f ]

Giancarlo Ferrari reports the following oops while trying to use kexec:

 Unable to handle kernel paging request at virtual address 80112f38
 pgd = fd7ef03e
 [80112f38] *pgd=0001141e(bad)
 Internal error: Oops: 80d [#1] PREEMPT SMP ARM
 ...

This is caused by machine_kexec() trying to set the kernel text to be
read/write, so it can poke values into the relocation code before
copying it - and an interrupt occuring which changes the page tables.
The subsequent writes then hit read-only sections that trigger a
data abort resulting in the above oops.

Fix this by copying the relocation code, and then writing the variables
into the destination, thereby avoiding the need to make the kernel text
read/write.

Reported-by: Giancarlo Ferrari &lt;giancarlo.ferrari89@gmail.com&gt;
Tested-by: Giancarlo Ferrari &lt;giancarlo.ferrari89@gmail.com&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&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 4d62e81b60d4025e2dfcd5ea531cc1394ce9226f ]

Giancarlo Ferrari reports the following oops while trying to use kexec:

 Unable to handle kernel paging request at virtual address 80112f38
 pgd = fd7ef03e
 [80112f38] *pgd=0001141e(bad)
 Internal error: Oops: 80d [#1] PREEMPT SMP ARM
 ...

This is caused by machine_kexec() trying to set the kernel text to be
read/write, so it can poke values into the relocation code before
copying it - and an interrupt occuring which changes the page tables.
The subsequent writes then hit read-only sections that trigger a
data abort resulting in the above oops.

Fix this by copying the relocation code, and then writing the variables
into the destination, thereby avoiding the need to make the kernel text
read/write.

Reported-by: Giancarlo Ferrari &lt;giancarlo.ferrari89@gmail.com&gt;
Tested-by: Giancarlo Ferrari &lt;giancarlo.ferrari89@gmail.com&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: 9019/1: kprobes: Avoid fortify_panic() when copying optprobe template</title>
<updated>2020-11-18T18:18:46+00:00</updated>
<author>
<name>Andrew Jeffery</name>
<email>andrew@aj.id.au</email>
</author>
<published>2020-10-22T00:43:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=0ef358bc8788046d31f536d4c99405a3e4970b01'/>
<id>0ef358bc8788046d31f536d4c99405a3e4970b01</id>
<content type='text'>
[ Upstream commit 9fa2e7af3d53a4b769136eccc32c02e128a4ee51 ]

Setting both CONFIG_KPROBES=y and CONFIG_FORTIFY_SOURCE=y on ARM leads
to a panic in memcpy() when injecting a kprobe despite the fixes found
in commit e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with
FORTIFY_SOURCE") and commit 0ac569bf6a79 ("ARM: 8834/1: Fix: kprobes:
optimized kprobes illegal instruction").

arch/arm/include/asm/kprobes.h effectively declares
the target type of the optprobe_template_entry assembly label as a u32
which leads memcpy()'s __builtin_object_size() call to determine that
the pointed-to object is of size four. However, the symbol is used as a handle
for the optimised probe assembly template that is at least 96 bytes in size.
The symbol's use despite its type blows up the memcpy() in ARM's
arch_prepare_optimized_kprobe() with a false-positive fortify_panic() when it
should instead copy the optimised probe template into place:

```
$ sudo perf probe -a aspeed_g6_pinctrl_probe
[  158.457252] detected buffer overflow in memcpy
[  158.458069] ------------[ cut here ]------------
[  158.458283] kernel BUG at lib/string.c:1153!
[  158.458436] Internal error: Oops - BUG: 0 [#1] SMP ARM
[  158.458768] Modules linked in:
[  158.459043] CPU: 1 PID: 99 Comm: perf Not tainted 5.9.0-rc7-00038-gc53ebf8167e9 #158
[  158.459296] Hardware name: Generic DT based system
[  158.459529] PC is at fortify_panic+0x18/0x20
[  158.459658] LR is at __irq_work_queue_local+0x3c/0x74
[  158.459831] pc : [&lt;8047451c&gt;]    lr : [&lt;8020ecd4&gt;]    psr: 60000013
[  158.460032] sp : be2d1d50  ip : be2d1c58  fp : be2d1d5c
[  158.460174] r10: 00000006  r9 : 00000000  r8 : 00000060
[  158.460348] r7 : 8011e434  r6 : b9e0b800  r5 : 7f000000  r4 : b9fe4f0c
[  158.460557] r3 : 80c04cc8  r2 : 00000000  r1 : be7c03cc  r0 : 00000022
[  158.460801] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[  158.461037] Control: 10c5387d  Table: b9cd806a  DAC: 00000051
[  158.461251] Process perf (pid: 99, stack limit = 0x81c71a69)
[  158.461472] Stack: (0xbe2d1d50 to 0xbe2d2000)
[  158.461757] 1d40:                                     be2d1d84 be2d1d60 8011e724 80474510
[  158.462104] 1d60: b9e0b800 b9fe4f0c 00000000 b9fe4f14 80c8ec80 be235000 be2d1d9c be2d1d88
[  158.462436] 1d80: 801cee44 8011e57c b9fe4f0c 00000000 be2d1dc4 be2d1da0 801d0ad0 801cedec
[  158.462742] 1da0: 00000000 00000000 b9fe4f00 ffffffea 00000000 be235000 be2d1de4 be2d1dc8
[  158.463087] 1dc0: 80204604 801d0738 00000000 00000000 b9fe4004 ffffffea be2d1e94 be2d1de8
[  158.463428] 1de0: 80205434 80204570 00385c00 00000000 00000000 00000000 be2d1e14 be2d1e08
[  158.463880] 1e00: 802ba014 b9fe4f00 b9e718c0 b9fe4f84 b9e71ec8 be2d1e24 00000000 00385c00
[  158.464365] 1e20: 00000000 626f7270 00000065 802b905c be2d1e94 0000002e 00000000 802b9914
[  158.464829] 1e40: be2d1e84 be2d1e50 802b9914 8028ff78 804629d0 b9e71ec0 0000002e b9e71ec0
[  158.465141] 1e60: be2d1ea8 80c04cc8 00000cc0 b9e713c4 00000002 80205834 80205834 0000002e
[  158.465488] 1e80: be235000 be235000 be2d1ea4 be2d1e98 80205854 80204e94 be2d1ecc be2d1ea8
[  158.465806] 1ea0: 801ee4a0 80205840 00000002 80c04cc8 00000000 0000002e 0000002e 00000000
[  158.466110] 1ec0: be2d1f0c be2d1ed0 801ee5c8 801ee428 00000000 be2d0000 006b1fd0 00000051
[  158.466398] 1ee0: 00000000 b9eedf00 0000002e 80204410 006b1fd0 be2d1f60 00000000 00000004
[  158.466763] 1f00: be2d1f24 be2d1f10 8020442c 801ee4c4 80205834 802c613c be2d1f5c be2d1f28
[  158.467102] 1f20: 802c60ac 8020441c be2d1fac be2d1f38 8010c764 802e9888 be2d1f5c b9eedf00
[  158.467447] 1f40: b9eedf00 006b1fd0 0000002e 00000000 be2d1f94 be2d1f60 802c634c 802c5fec
[  158.467812] 1f60: 00000000 00000000 00000000 80c04cc8 006b1fd0 00000003 76f7a610 00000004
[  158.468155] 1f80: 80100284 be2d0000 be2d1fa4 be2d1f98 802c63ec 802c62e8 00000000 be2d1fa8
[  158.468508] 1fa0: 80100080 802c63e0 006b1fd0 00000003 00000003 006b1fd0 0000002e 00000000
[  158.468858] 1fc0: 006b1fd0 00000003 76f7a610 00000004 006b1fb0 0026d348 00000017 7ef2738c
[  158.469202] 1fe0: 76f3431c 7ef272d8 0014ec50 76f34338 60000010 00000003 00000000 00000000
[  158.469461] Backtrace:
[  158.469683] [&lt;80474504&gt;] (fortify_panic) from [&lt;8011e724&gt;] (arch_prepare_optimized_kprobe+0x1b4/0x1f8)
[  158.470021] [&lt;8011e570&gt;] (arch_prepare_optimized_kprobe) from [&lt;801cee44&gt;] (alloc_aggr_kprobe+0x64/0x70)
[  158.470287]  r9:be235000 r8:80c8ec80 r7:b9fe4f14 r6:00000000 r5:b9fe4f0c r4:b9e0b800
[  158.470478] [&lt;801cede0&gt;] (alloc_aggr_kprobe) from [&lt;801d0ad0&gt;] (register_kprobe+0x3a4/0x5a0)
[  158.470685]  r5:00000000 r4:b9fe4f0c
[  158.470790] [&lt;801d072c&gt;] (register_kprobe) from [&lt;80204604&gt;] (__register_trace_kprobe+0xa0/0xa4)
[  158.471001]  r9:be235000 r8:00000000 r7:ffffffea r6:b9fe4f00 r5:00000000 r4:00000000
[  158.471188] [&lt;80204564&gt;] (__register_trace_kprobe) from [&lt;80205434&gt;] (trace_kprobe_create+0x5ac/0x9ac)
[  158.471408]  r7:ffffffea r6:b9fe4004 r5:00000000 r4:00000000
[  158.471553] [&lt;80204e88&gt;] (trace_kprobe_create) from [&lt;80205854&gt;] (create_or_delete_trace_kprobe+0x20/0x3c)
[  158.471766]  r10:be235000 r9:be235000 r8:0000002e r7:80205834 r6:80205834 r5:00000002
[  158.471949]  r4:b9e713c4
[  158.472027] [&lt;80205834&gt;] (create_or_delete_trace_kprobe) from [&lt;801ee4a0&gt;] (trace_run_command+0x84/0x9c)
[  158.472255] [&lt;801ee41c&gt;] (trace_run_command) from [&lt;801ee5c8&gt;] (trace_parse_run_command+0x110/0x1f8)
[  158.472471]  r6:00000000 r5:0000002e r4:0000002e
[  158.472594] [&lt;801ee4b8&gt;] (trace_parse_run_command) from [&lt;8020442c&gt;] (probes_write+0x1c/0x28)
[  158.472800]  r10:00000004 r9:00000000 r8:be2d1f60 r7:006b1fd0 r6:80204410 r5:0000002e
[  158.472968]  r4:b9eedf00
[  158.473046] [&lt;80204410&gt;] (probes_write) from [&lt;802c60ac&gt;] (vfs_write+0xcc/0x1e8)
[  158.473226] [&lt;802c5fe0&gt;] (vfs_write) from [&lt;802c634c&gt;] (ksys_write+0x70/0xf8)
[  158.473400]  r8:00000000 r7:0000002e r6:006b1fd0 r5:b9eedf00 r4:b9eedf00
[  158.473567] [&lt;802c62dc&gt;] (ksys_write) from [&lt;802c63ec&gt;] (sys_write+0x18/0x1c)
[  158.473745]  r9:be2d0000 r8:80100284 r7:00000004 r6:76f7a610 r5:00000003 r4:006b1fd0
[  158.473932] [&lt;802c63d4&gt;] (sys_write) from [&lt;80100080&gt;] (ret_fast_syscall+0x0/0x54)
[  158.474126] Exception stack(0xbe2d1fa8 to 0xbe2d1ff0)
[  158.474305] 1fa0:                   006b1fd0 00000003 00000003 006b1fd0 0000002e 00000000
[  158.474573] 1fc0: 006b1fd0 00000003 76f7a610 00000004 006b1fb0 0026d348 00000017 7ef2738c
[  158.474811] 1fe0: 76f3431c 7ef272d8 0014ec50 76f34338
[  158.475171] Code: e24cb004 e1a01000 e59f0004 ebf40dd3 (e7f001f2)
[  158.475847] ---[ end trace 55a5b31c08a29f00 ]---
[  158.476088] Kernel panic - not syncing: Fatal exception
[  158.476375] CPU0: stopping
[  158.476709] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G      D           5.9.0-rc7-00038-gc53ebf8167e9 #158
[  158.477176] Hardware name: Generic DT based system
[  158.477411] Backtrace:
[  158.477604] [&lt;8010dd28&gt;] (dump_backtrace) from [&lt;8010dfd4&gt;] (show_stack+0x20/0x24)
[  158.477990]  r7:00000000 r6:60000193 r5:00000000 r4:80c2f634
[  158.478323] [&lt;8010dfb4&gt;] (show_stack) from [&lt;8046390c&gt;] (dump_stack+0xcc/0xe8)
[  158.478686] [&lt;80463840&gt;] (dump_stack) from [&lt;80110750&gt;] (handle_IPI+0x334/0x3a0)
[  158.479063]  r7:00000000 r6:00000004 r5:80b65cc8 r4:80c78278
[  158.479352] [&lt;8011041c&gt;] (handle_IPI) from [&lt;801013f8&gt;] (gic_handle_irq+0x88/0x94)
[  158.479757]  r10:10c5387d r9:80c01ed8 r8:00000000 r7:c0802000 r6:80c0537c r5:000003ff
[  158.480146]  r4:c080200c r3:fffffff4
[  158.480364] [&lt;80101370&gt;] (gic_handle_irq) from [&lt;80100b6c&gt;] (__irq_svc+0x6c/0x90)
[  158.480748] Exception stack(0x80c01ed8 to 0x80c01f20)
[  158.481031] 1ec0:                                                       000128bc 00000000
[  158.481499] 1ee0: be7b8174 8011d3a0 80c00000 00000000 80c04cec 80c04d28 80c5d7c2 80a026d4
[  158.482091] 1f00: 10c5387d 80c01f34 80c01f38 80c01f28 80109554 80109558 60000013 ffffffff
[  158.482621]  r9:80c00000 r8:80c5d7c2 r7:80c01f0c r6:ffffffff r5:60000013 r4:80109558
[  158.482983] [&lt;80109518&gt;] (arch_cpu_idle) from [&lt;80818780&gt;] (default_idle_call+0x38/0x120)
[  158.483360] [&lt;80818748&gt;] (default_idle_call) from [&lt;801585a8&gt;] (do_idle+0xd4/0x158)
[  158.483945]  r5:00000000 r4:80c00000
[  158.484237] [&lt;801584d4&gt;] (do_idle) from [&lt;801588f4&gt;] (cpu_startup_entry+0x28/0x2c)
[  158.484784]  r9:80c78000 r8:00000000 r7:80c78000 r6:80c78040 r5:80c04cc0 r4:000000d6
[  158.485328] [&lt;801588cc&gt;] (cpu_startup_entry) from [&lt;80810a78&gt;] (rest_init+0x9c/0xbc)
[  158.485930] [&lt;808109dc&gt;] (rest_init) from [&lt;80b00ae4&gt;] (arch_call_rest_init+0x18/0x1c)
[  158.486503]  r5:80c04cc0 r4:00000001
[  158.486857] [&lt;80b00acc&gt;] (arch_call_rest_init) from [&lt;80b00fcc&gt;] (start_kernel+0x46c/0x548)
[  158.487589] [&lt;80b00b60&gt;] (start_kernel) from [&lt;00000000&gt;] (0x0)
```

Fixes: e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE")
Fixes: 0ac569bf6a79 ("ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction")
Suggested-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Andrew Jeffery &lt;andrew@aj.id.au&gt;
Tested-by: Luka Oreskovic &lt;luka.oreskovic@sartura.hr&gt;
Tested-by: Joel Stanley &lt;joel@jms.id.au&gt;
Reviewed-by: Joel Stanley &lt;joel@jms.id.au&gt;
Acked-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Luka Oreskovic &lt;luka.oreskovic@sartura.hr&gt;
Cc: Juraj Vijtiuk &lt;juraj.vijtiuk@sartura.hr&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&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 9fa2e7af3d53a4b769136eccc32c02e128a4ee51 ]

Setting both CONFIG_KPROBES=y and CONFIG_FORTIFY_SOURCE=y on ARM leads
to a panic in memcpy() when injecting a kprobe despite the fixes found
in commit e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with
FORTIFY_SOURCE") and commit 0ac569bf6a79 ("ARM: 8834/1: Fix: kprobes:
optimized kprobes illegal instruction").

arch/arm/include/asm/kprobes.h effectively declares
the target type of the optprobe_template_entry assembly label as a u32
which leads memcpy()'s __builtin_object_size() call to determine that
the pointed-to object is of size four. However, the symbol is used as a handle
for the optimised probe assembly template that is at least 96 bytes in size.
The symbol's use despite its type blows up the memcpy() in ARM's
arch_prepare_optimized_kprobe() with a false-positive fortify_panic() when it
should instead copy the optimised probe template into place:

```
$ sudo perf probe -a aspeed_g6_pinctrl_probe
[  158.457252] detected buffer overflow in memcpy
[  158.458069] ------------[ cut here ]------------
[  158.458283] kernel BUG at lib/string.c:1153!
[  158.458436] Internal error: Oops - BUG: 0 [#1] SMP ARM
[  158.458768] Modules linked in:
[  158.459043] CPU: 1 PID: 99 Comm: perf Not tainted 5.9.0-rc7-00038-gc53ebf8167e9 #158
[  158.459296] Hardware name: Generic DT based system
[  158.459529] PC is at fortify_panic+0x18/0x20
[  158.459658] LR is at __irq_work_queue_local+0x3c/0x74
[  158.459831] pc : [&lt;8047451c&gt;]    lr : [&lt;8020ecd4&gt;]    psr: 60000013
[  158.460032] sp : be2d1d50  ip : be2d1c58  fp : be2d1d5c
[  158.460174] r10: 00000006  r9 : 00000000  r8 : 00000060
[  158.460348] r7 : 8011e434  r6 : b9e0b800  r5 : 7f000000  r4 : b9fe4f0c
[  158.460557] r3 : 80c04cc8  r2 : 00000000  r1 : be7c03cc  r0 : 00000022
[  158.460801] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[  158.461037] Control: 10c5387d  Table: b9cd806a  DAC: 00000051
[  158.461251] Process perf (pid: 99, stack limit = 0x81c71a69)
[  158.461472] Stack: (0xbe2d1d50 to 0xbe2d2000)
[  158.461757] 1d40:                                     be2d1d84 be2d1d60 8011e724 80474510
[  158.462104] 1d60: b9e0b800 b9fe4f0c 00000000 b9fe4f14 80c8ec80 be235000 be2d1d9c be2d1d88
[  158.462436] 1d80: 801cee44 8011e57c b9fe4f0c 00000000 be2d1dc4 be2d1da0 801d0ad0 801cedec
[  158.462742] 1da0: 00000000 00000000 b9fe4f00 ffffffea 00000000 be235000 be2d1de4 be2d1dc8
[  158.463087] 1dc0: 80204604 801d0738 00000000 00000000 b9fe4004 ffffffea be2d1e94 be2d1de8
[  158.463428] 1de0: 80205434 80204570 00385c00 00000000 00000000 00000000 be2d1e14 be2d1e08
[  158.463880] 1e00: 802ba014 b9fe4f00 b9e718c0 b9fe4f84 b9e71ec8 be2d1e24 00000000 00385c00
[  158.464365] 1e20: 00000000 626f7270 00000065 802b905c be2d1e94 0000002e 00000000 802b9914
[  158.464829] 1e40: be2d1e84 be2d1e50 802b9914 8028ff78 804629d0 b9e71ec0 0000002e b9e71ec0
[  158.465141] 1e60: be2d1ea8 80c04cc8 00000cc0 b9e713c4 00000002 80205834 80205834 0000002e
[  158.465488] 1e80: be235000 be235000 be2d1ea4 be2d1e98 80205854 80204e94 be2d1ecc be2d1ea8
[  158.465806] 1ea0: 801ee4a0 80205840 00000002 80c04cc8 00000000 0000002e 0000002e 00000000
[  158.466110] 1ec0: be2d1f0c be2d1ed0 801ee5c8 801ee428 00000000 be2d0000 006b1fd0 00000051
[  158.466398] 1ee0: 00000000 b9eedf00 0000002e 80204410 006b1fd0 be2d1f60 00000000 00000004
[  158.466763] 1f00: be2d1f24 be2d1f10 8020442c 801ee4c4 80205834 802c613c be2d1f5c be2d1f28
[  158.467102] 1f20: 802c60ac 8020441c be2d1fac be2d1f38 8010c764 802e9888 be2d1f5c b9eedf00
[  158.467447] 1f40: b9eedf00 006b1fd0 0000002e 00000000 be2d1f94 be2d1f60 802c634c 802c5fec
[  158.467812] 1f60: 00000000 00000000 00000000 80c04cc8 006b1fd0 00000003 76f7a610 00000004
[  158.468155] 1f80: 80100284 be2d0000 be2d1fa4 be2d1f98 802c63ec 802c62e8 00000000 be2d1fa8
[  158.468508] 1fa0: 80100080 802c63e0 006b1fd0 00000003 00000003 006b1fd0 0000002e 00000000
[  158.468858] 1fc0: 006b1fd0 00000003 76f7a610 00000004 006b1fb0 0026d348 00000017 7ef2738c
[  158.469202] 1fe0: 76f3431c 7ef272d8 0014ec50 76f34338 60000010 00000003 00000000 00000000
[  158.469461] Backtrace:
[  158.469683] [&lt;80474504&gt;] (fortify_panic) from [&lt;8011e724&gt;] (arch_prepare_optimized_kprobe+0x1b4/0x1f8)
[  158.470021] [&lt;8011e570&gt;] (arch_prepare_optimized_kprobe) from [&lt;801cee44&gt;] (alloc_aggr_kprobe+0x64/0x70)
[  158.470287]  r9:be235000 r8:80c8ec80 r7:b9fe4f14 r6:00000000 r5:b9fe4f0c r4:b9e0b800
[  158.470478] [&lt;801cede0&gt;] (alloc_aggr_kprobe) from [&lt;801d0ad0&gt;] (register_kprobe+0x3a4/0x5a0)
[  158.470685]  r5:00000000 r4:b9fe4f0c
[  158.470790] [&lt;801d072c&gt;] (register_kprobe) from [&lt;80204604&gt;] (__register_trace_kprobe+0xa0/0xa4)
[  158.471001]  r9:be235000 r8:00000000 r7:ffffffea r6:b9fe4f00 r5:00000000 r4:00000000
[  158.471188] [&lt;80204564&gt;] (__register_trace_kprobe) from [&lt;80205434&gt;] (trace_kprobe_create+0x5ac/0x9ac)
[  158.471408]  r7:ffffffea r6:b9fe4004 r5:00000000 r4:00000000
[  158.471553] [&lt;80204e88&gt;] (trace_kprobe_create) from [&lt;80205854&gt;] (create_or_delete_trace_kprobe+0x20/0x3c)
[  158.471766]  r10:be235000 r9:be235000 r8:0000002e r7:80205834 r6:80205834 r5:00000002
[  158.471949]  r4:b9e713c4
[  158.472027] [&lt;80205834&gt;] (create_or_delete_trace_kprobe) from [&lt;801ee4a0&gt;] (trace_run_command+0x84/0x9c)
[  158.472255] [&lt;801ee41c&gt;] (trace_run_command) from [&lt;801ee5c8&gt;] (trace_parse_run_command+0x110/0x1f8)
[  158.472471]  r6:00000000 r5:0000002e r4:0000002e
[  158.472594] [&lt;801ee4b8&gt;] (trace_parse_run_command) from [&lt;8020442c&gt;] (probes_write+0x1c/0x28)
[  158.472800]  r10:00000004 r9:00000000 r8:be2d1f60 r7:006b1fd0 r6:80204410 r5:0000002e
[  158.472968]  r4:b9eedf00
[  158.473046] [&lt;80204410&gt;] (probes_write) from [&lt;802c60ac&gt;] (vfs_write+0xcc/0x1e8)
[  158.473226] [&lt;802c5fe0&gt;] (vfs_write) from [&lt;802c634c&gt;] (ksys_write+0x70/0xf8)
[  158.473400]  r8:00000000 r7:0000002e r6:006b1fd0 r5:b9eedf00 r4:b9eedf00
[  158.473567] [&lt;802c62dc&gt;] (ksys_write) from [&lt;802c63ec&gt;] (sys_write+0x18/0x1c)
[  158.473745]  r9:be2d0000 r8:80100284 r7:00000004 r6:76f7a610 r5:00000003 r4:006b1fd0
[  158.473932] [&lt;802c63d4&gt;] (sys_write) from [&lt;80100080&gt;] (ret_fast_syscall+0x0/0x54)
[  158.474126] Exception stack(0xbe2d1fa8 to 0xbe2d1ff0)
[  158.474305] 1fa0:                   006b1fd0 00000003 00000003 006b1fd0 0000002e 00000000
[  158.474573] 1fc0: 006b1fd0 00000003 76f7a610 00000004 006b1fb0 0026d348 00000017 7ef2738c
[  158.474811] 1fe0: 76f3431c 7ef272d8 0014ec50 76f34338
[  158.475171] Code: e24cb004 e1a01000 e59f0004 ebf40dd3 (e7f001f2)
[  158.475847] ---[ end trace 55a5b31c08a29f00 ]---
[  158.476088] Kernel panic - not syncing: Fatal exception
[  158.476375] CPU0: stopping
[  158.476709] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G      D           5.9.0-rc7-00038-gc53ebf8167e9 #158
[  158.477176] Hardware name: Generic DT based system
[  158.477411] Backtrace:
[  158.477604] [&lt;8010dd28&gt;] (dump_backtrace) from [&lt;8010dfd4&gt;] (show_stack+0x20/0x24)
[  158.477990]  r7:00000000 r6:60000193 r5:00000000 r4:80c2f634
[  158.478323] [&lt;8010dfb4&gt;] (show_stack) from [&lt;8046390c&gt;] (dump_stack+0xcc/0xe8)
[  158.478686] [&lt;80463840&gt;] (dump_stack) from [&lt;80110750&gt;] (handle_IPI+0x334/0x3a0)
[  158.479063]  r7:00000000 r6:00000004 r5:80b65cc8 r4:80c78278
[  158.479352] [&lt;8011041c&gt;] (handle_IPI) from [&lt;801013f8&gt;] (gic_handle_irq+0x88/0x94)
[  158.479757]  r10:10c5387d r9:80c01ed8 r8:00000000 r7:c0802000 r6:80c0537c r5:000003ff
[  158.480146]  r4:c080200c r3:fffffff4
[  158.480364] [&lt;80101370&gt;] (gic_handle_irq) from [&lt;80100b6c&gt;] (__irq_svc+0x6c/0x90)
[  158.480748] Exception stack(0x80c01ed8 to 0x80c01f20)
[  158.481031] 1ec0:                                                       000128bc 00000000
[  158.481499] 1ee0: be7b8174 8011d3a0 80c00000 00000000 80c04cec 80c04d28 80c5d7c2 80a026d4
[  158.482091] 1f00: 10c5387d 80c01f34 80c01f38 80c01f28 80109554 80109558 60000013 ffffffff
[  158.482621]  r9:80c00000 r8:80c5d7c2 r7:80c01f0c r6:ffffffff r5:60000013 r4:80109558
[  158.482983] [&lt;80109518&gt;] (arch_cpu_idle) from [&lt;80818780&gt;] (default_idle_call+0x38/0x120)
[  158.483360] [&lt;80818748&gt;] (default_idle_call) from [&lt;801585a8&gt;] (do_idle+0xd4/0x158)
[  158.483945]  r5:00000000 r4:80c00000
[  158.484237] [&lt;801584d4&gt;] (do_idle) from [&lt;801588f4&gt;] (cpu_startup_entry+0x28/0x2c)
[  158.484784]  r9:80c78000 r8:00000000 r7:80c78000 r6:80c78040 r5:80c04cc0 r4:000000d6
[  158.485328] [&lt;801588cc&gt;] (cpu_startup_entry) from [&lt;80810a78&gt;] (rest_init+0x9c/0xbc)
[  158.485930] [&lt;808109dc&gt;] (rest_init) from [&lt;80b00ae4&gt;] (arch_call_rest_init+0x18/0x1c)
[  158.486503]  r5:80c04cc0 r4:00000001
[  158.486857] [&lt;80b00acc&gt;] (arch_call_rest_init) from [&lt;80b00fcc&gt;] (start_kernel+0x46c/0x548)
[  158.487589] [&lt;80b00b60&gt;] (start_kernel) from [&lt;00000000&gt;] (0x0)
```

Fixes: e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE")
Fixes: 0ac569bf6a79 ("ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction")
Suggested-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Andrew Jeffery &lt;andrew@aj.id.au&gt;
Tested-by: Luka Oreskovic &lt;luka.oreskovic@sartura.hr&gt;
Tested-by: Joel Stanley &lt;joel@jms.id.au&gt;
Reviewed-by: Joel Stanley &lt;joel@jms.id.au&gt;
Acked-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Luka Oreskovic &lt;luka.oreskovic@sartura.hr&gt;
Cc: Juraj Vijtiuk &lt;juraj.vijtiuk@sartura.hr&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch</title>
<updated>2020-10-01T11:14:54+00:00</updated>
<author>
<name>Marc Zyngier</name>
<email>maz@kernel.org</email>
</author>
<published>2020-09-15T10:42:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=1fa2c32e375e87834a9a2af93210201039f7e1ee'/>
<id>1fa2c32e375e87834a9a2af93210201039f7e1ee</id>
<content type='text'>
commit c4ad98e4b72cb5be30ea282fce935248f2300e62 upstream.

KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).

This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.

In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0ef54c ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").

Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce
kvm_vcpu_trap_is_exec_fault() that only return true when no faulting
on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to
kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't
specific to data abort.

Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Reviewed-by: Will Deacon &lt;will@kernel.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org
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 c4ad98e4b72cb5be30ea282fce935248f2300e62 upstream.

KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).

This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.

In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0ef54c ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").

Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce
kvm_vcpu_trap_is_exec_fault() that only return true when no faulting
on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to
kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't
specific to data abort.

Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Reviewed-by: Will Deacon &lt;will@kernel.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: Pass MMU notifier range flags to kvm_unmap_hva_range()</title>
<updated>2020-08-26T08:31:07+00:00</updated>
<author>
<name>Will Deacon</name>
<email>will@kernel.org</email>
</author>
<published>2020-08-11T10:27:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=a53dc16499fc9efd8db0b40e45f3344a0fb9c0a2'/>
<id>a53dc16499fc9efd8db0b40e45f3344a0fb9c0a2</id>
<content type='text'>
commit fdfe7cbd58806522e799e2a50a15aee7f2cbb7b6 upstream.

The 'flags' field of 'struct mmu_notifier_range' is used to indicate
whether invalidate_range_{start,end}() are permitted to block. In the
case of kvm_mmu_notifier_invalidate_range_start(), this field is not
forwarded on to the architecture-specific implementation of
kvm_unmap_hva_range() and therefore the backend cannot sensibly decide
whether or not to block.

Add an extra 'flags' parameter to kvm_unmap_hva_range() so that
architectures are aware as to whether or not they are permitted to block.

Cc: &lt;stable@vger.kernel.org&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: Suzuki K Poulose &lt;suzuki.poulose@arm.com&gt;
Cc: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Message-Id: &lt;20200811102725.7121-2-will@kernel.org&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
[will: Backport to 4.19; use 'blockable' instead of non-existent range flags]
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 fdfe7cbd58806522e799e2a50a15aee7f2cbb7b6 upstream.

The 'flags' field of 'struct mmu_notifier_range' is used to indicate
whether invalidate_range_{start,end}() are permitted to block. In the
case of kvm_mmu_notifier_invalidate_range_start(), this field is not
forwarded on to the architecture-specific implementation of
kvm_unmap_hva_range() and therefore the backend cannot sensibly decide
whether or not to block.

Add an extra 'flags' parameter to kvm_unmap_hva_range() so that
architectures are aware as to whether or not they are permitted to block.

Cc: &lt;stable@vger.kernel.org&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: Suzuki K Poulose &lt;suzuki.poulose@arm.com&gt;
Cc: James Morse &lt;james.morse@arm.com&gt;
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Message-Id: &lt;20200811102725.7121-2-will@kernel.org&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
[will: Backport to 4.19; use 'blockable' instead of non-existent range flags]
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>ARM: percpu.h: fix build error</title>
<updated>2020-08-07T07:36:20+00:00</updated>
<author>
<name>Grygorii Strashko</name>
<email>grygorii.strashko@ti.com</email>
</author>
<published>2020-07-30T19:05:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=546271c2c8d3a4f2d5fd07d43faf49d0b4423dde'/>
<id>546271c2c8d3a4f2d5fd07d43faf49d0b4423dde</id>
<content type='text'>
commit aa54ea903abb02303bf55855fb51e3fcee135d70 upstream.

Fix build error for the case:
  defined(CONFIG_SMP) &amp;&amp; !defined(CONFIG_CPU_V6)

config: keystone_defconfig

  CC      arch/arm/kernel/signal.o
  In file included from ../include/linux/random.h:14,
                    from ../arch/arm/kernel/signal.c:8:
  ../arch/arm/include/asm/percpu.h: In function ‘__my_cpu_offset’:
  ../arch/arm/include/asm/percpu.h:29:34: error: ‘current_stack_pointer’ undeclared (first use in this function); did you mean ‘user_stack_pointer’?
      : "Q" (*(const unsigned long *)current_stack_pointer));
                                     ^~~~~~~~~~~~~~~~~~~~~
                                     user_stack_pointer

Fixes: f227e3ec3b5c ("random32: update the net random state on interrupt and activity")
Signed-off-by: Grygorii Strashko &lt;grygorii.strashko@ti.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.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 aa54ea903abb02303bf55855fb51e3fcee135d70 upstream.

Fix build error for the case:
  defined(CONFIG_SMP) &amp;&amp; !defined(CONFIG_CPU_V6)

config: keystone_defconfig

  CC      arch/arm/kernel/signal.o
  In file included from ../include/linux/random.h:14,
                    from ../arch/arm/kernel/signal.c:8:
  ../arch/arm/include/asm/percpu.h: In function ‘__my_cpu_offset’:
  ../arch/arm/include/asm/percpu.h:29:34: error: ‘current_stack_pointer’ undeclared (first use in this function); did you mean ‘user_stack_pointer’?
      : "Q" (*(const unsigned long *)current_stack_pointer));
                                     ^~~~~~~~~~~~~~~~~~~~~
                                     user_stack_pointer

Fixes: f227e3ec3b5c ("random32: update the net random state on interrupt and activity")
Signed-off-by: Grygorii Strashko &lt;grygorii.strashko@ti.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: Synchronize sysreg state on injecting an AArch32 exception</title>
<updated>2020-06-22T07:05:09+00:00</updated>
<author>
<name>Marc Zyngier</name>
<email>maz@kernel.org</email>
</author>
<published>2020-06-09T07:50:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=929fccde381ef382c519c52c2746ab5febc30442'/>
<id>929fccde381ef382c519c52c2746ab5febc30442</id>
<content type='text'>
commit 0370964dd3ff7d3d406f292cb443a927952cbd05 upstream.

On a VHE system, the EL1 state is left in the CPU most of the time,
and only syncronized back to memory when vcpu_put() is called (most
of the time on preemption).

Which means that when injecting an exception, we'd better have a way
to either:
(1) write directly to the EL1 sysregs
(2) synchronize the state back to memory, and do the changes there

For an AArch64, we already do (1), so we are safe. Unfortunately,
doing the same thing for AArch32 would be pretty invasive. Instead,
we can easily implement (2) by calling the put/load architectural
backends, and keep preemption disabled. We can then reload the
state back into EL1.

Cc: stable@vger.kernel.org
Reported-by: James Morse &lt;james.morse@arm.com&gt;
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 0370964dd3ff7d3d406f292cb443a927952cbd05 upstream.

On a VHE system, the EL1 state is left in the CPU most of the time,
and only syncronized back to memory when vcpu_put() is called (most
of the time on preemption).

Which means that when injecting an exception, we'd better have a way
to either:
(1) write directly to the EL1 sysregs
(2) synchronize the state back to memory, and do the changes there

For an AArch64, we already do (1), so we are safe. Unfortunately,
doing the same thing for AArch32 would be pretty invasive. Instead,
we can easily implement (2) by calling the put/load architectural
backends, and keep preemption disabled. We can then reload the
state back into EL1.

Cc: stable@vger.kernel.org
Reported-by: James Morse &lt;james.morse@arm.com&gt;
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>ARM: uaccess: fix DACR mismatch with nested exceptions</title>
<updated>2020-06-03T06:19:35+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@armlinux.org.uk</email>
</author>
<published>2020-05-03T12:24:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=efae52019b283fa48ed05f23a5cdd278e7be2984'/>
<id>efae52019b283fa48ed05f23a5cdd278e7be2984</id>
<content type='text'>
[ Upstream commit 71f8af1110101facfad68989ff91f88f8e2c3e22 ]

Tomas Paukrt reports that his SAM9X60 based system (ARM926, ARMv5TJ)
fails to fix up alignment faults, eventually resulting in a kernel
oops.

The problem occurs when using CONFIG_CPU_USE_DOMAINS with commit
e6978e4bf181 ("ARM: save and reset the address limit when entering an
exception").  This is because the address limit is set back to
TASK_SIZE on exception entry, and, although it is restored on exception
exit, the domain register is not.

Hence, this sequence can occur:

  interrupt
    pt_regs-&gt;addr_limit = addr_limit		// USER_DS
    addr_limit = USER_DS
    alignment exception
    __probe_kernel_read()
      old_fs = get_fs()				// USER_DS
      set_fs(KERNEL_DS)
        addr_limit = KERNEL_DS
        dacr.kernel = DOMAIN_MANAGER
        interrupt
          pt_regs-&gt;addr_limit = addr_limit	// KERNEL_DS
          addr_limit = USER_DS
          alignment exception
          __probe_kernel_read()
            old_fs = get_fs()			// USER_DS
            set_fs(KERNEL_DS)
              addr_limit = KERNEL_DS
              dacr.kernel = DOMAIN_MANAGER
            ...
            set_fs(old_fs)
              addr_limit = USER_DS
              dacr.kernel = DOMAIN_CLIENT
          ...
          addr_limit = pt_regs-&gt;addr_limit	// KERNEL_DS
        interrupt returns

At this point, addr_limit is correctly restored to KERNEL_DS for
__probe_kernel_read() to continue execution, but dacr.kernel is not,
it has been reset by the set_fs(old_fs) to DOMAIN_CLIENT.

This would not have happened prior to the mentioned commit, because
addr_limit would remain KERNEL_DS, so get_fs() would have returned
KERNEL_DS, and so would correctly nest.

This commit fixes the problem by also saving the DACR on exception
entry if either CONFIG_CPU_SW_DOMAIN_PAN or CONFIG_CPU_USE_DOMAINS are
enabled, and resetting the DACR appropriately on exception entry to
match addr_limit and PAN settings.

Fixes: e6978e4bf181 ("ARM: save and reset the address limit when entering an exception")
Reported-by: Tomas Paukrt &lt;tomas.paukrt@advantech.cz&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&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 71f8af1110101facfad68989ff91f88f8e2c3e22 ]

Tomas Paukrt reports that his SAM9X60 based system (ARM926, ARMv5TJ)
fails to fix up alignment faults, eventually resulting in a kernel
oops.

The problem occurs when using CONFIG_CPU_USE_DOMAINS with commit
e6978e4bf181 ("ARM: save and reset the address limit when entering an
exception").  This is because the address limit is set back to
TASK_SIZE on exception entry, and, although it is restored on exception
exit, the domain register is not.

Hence, this sequence can occur:

  interrupt
    pt_regs-&gt;addr_limit = addr_limit		// USER_DS
    addr_limit = USER_DS
    alignment exception
    __probe_kernel_read()
      old_fs = get_fs()				// USER_DS
      set_fs(KERNEL_DS)
        addr_limit = KERNEL_DS
        dacr.kernel = DOMAIN_MANAGER
        interrupt
          pt_regs-&gt;addr_limit = addr_limit	// KERNEL_DS
          addr_limit = USER_DS
          alignment exception
          __probe_kernel_read()
            old_fs = get_fs()			// USER_DS
            set_fs(KERNEL_DS)
              addr_limit = KERNEL_DS
              dacr.kernel = DOMAIN_MANAGER
            ...
            set_fs(old_fs)
              addr_limit = USER_DS
              dacr.kernel = DOMAIN_CLIENT
          ...
          addr_limit = pt_regs-&gt;addr_limit	// KERNEL_DS
        interrupt returns

At this point, addr_limit is correctly restored to KERNEL_DS for
__probe_kernel_read() to continue execution, but dacr.kernel is not,
it has been reset by the set_fs(old_fs) to DOMAIN_CLIENT.

This would not have happened prior to the mentioned commit, because
addr_limit would remain KERNEL_DS, so get_fs() would have returned
KERNEL_DS, and so would correctly nest.

This commit fixes the problem by also saving the DACR on exception
entry if either CONFIG_CPU_SW_DOMAIN_PAN or CONFIG_CPU_USE_DOMAINS are
enabled, and resetting the DACR appropriately on exception entry to
match addr_limit and PAN settings.

Fixes: e6978e4bf181 ("ARM: save and reset the address limit when entering an exception")
Reported-by: Tomas Paukrt &lt;tomas.paukrt@advantech.cz&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: uaccess: integrate uaccess_save and uaccess_restore</title>
<updated>2020-06-03T06:19:35+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@armlinux.org.uk</email>
</author>
<published>2020-05-03T12:14:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=5ab3d9d68cc9d7bbf1223e63e5c5562c29aa3baf'/>
<id>5ab3d9d68cc9d7bbf1223e63e5c5562c29aa3baf</id>
<content type='text'>
[ Upstream commit 8ede890b0bcebe8c760aacfe20e934d98c3dc6aa ]

Integrate uaccess_save / uaccess_restore macros into the new
uaccess_entry / uaccess_exit macros respectively.

Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&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 8ede890b0bcebe8c760aacfe20e934d98c3dc6aa ]

Integrate uaccess_save / uaccess_restore macros into the new
uaccess_entry / uaccess_exit macros respectively.

Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: uaccess: consolidate uaccess asm to asm/uaccess-asm.h</title>
<updated>2020-06-03T06:19:34+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@armlinux.org.uk</email>
</author>
<published>2020-05-03T12:03:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=abd641e92d6e6dbc86778b3843811368b5ffce08'/>
<id>abd641e92d6e6dbc86778b3843811368b5ffce08</id>
<content type='text'>
[ Upstream commit 747ffc2fcf969eff9309d7f2d1d61cb8b9e1bb40 ]

Consolidate the user access assembly code to asm/uaccess-asm.h.  This
moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable,
uaccess_disable, uaccess_save, uaccess_restore macros, and creates two
new ones for exception entry and exit - uaccess_entry and uaccess_exit.

This makes the uaccess_save and uaccess_restore macros private to
asm/uaccess-asm.h.

Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&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 747ffc2fcf969eff9309d7f2d1d61cb8b9e1bb40 ]

Consolidate the user access assembly code to asm/uaccess-asm.h.  This
moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable,
uaccess_disable, uaccess_save, uaccess_restore macros, and creates two
new ones for exception entry and exit - uaccess_entry and uaccess_exit.

This makes the uaccess_save and uaccess_restore macros private to
asm/uaccess-asm.h.

Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
