linux-stable.git/arch/powerpc/kernel, branch v5.4.76 Linux kernel stable tree powerpc: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation 2020-11-05T10:43:31+00:00 Michael Neuling mikey@neuling.org 2020-10-13T04:37:40+00:00 415043c3ec0dea6bf3a347f2ce22b0461b9e161a commit 1da4a0272c5469169f78cd76cf175ff984f52f06 upstream. __get_user_atomic_128_aligned() stores to kaddr using stvx which is a VMX store instruction, hence kaddr must be 16 byte aligned otherwise the store won't occur as expected. Unfortunately when we call __get_user_atomic_128_aligned() in p9_hmi_special_emu(), the buffer we pass as kaddr (ie. vbuf) isn't guaranteed to be 16B aligned. This means that the write to vbuf in __get_user_atomic_128_aligned() has the bottom bits of the address truncated. This results in other local variables being overwritten. Also vbuf will not contain the correct data which results in the userspace emulation being wrong and hence undetected user data corruption. In the past we've been mostly lucky as vbuf has ended up aligned but this is fragile and isn't always true. CONFIG_STACKPROTECTOR in particular can change the stack arrangement enough that our luck runs out. This issue only occurs on POWER9 Nimbus <= DD2.1 bare metal. The fix is to align vbuf to a 16 byte boundary. Fixes: 5080332c2c89 ("powerpc/64s: Add workaround for P9 vector CI load issue") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201013043741.743413-1-mikey@neuling.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1da4a0272c5469169f78cd76cf175ff984f52f06 upstream.

__get_user_atomic_128_aligned() stores to kaddr using stvx which is a
VMX store instruction, hence kaddr must be 16 byte aligned otherwise
the store won't occur as expected.

Unfortunately when we call __get_user_atomic_128_aligned() in
p9_hmi_special_emu(), the buffer we pass as kaddr (ie. vbuf) isn't
guaranteed to be 16B aligned. This means that the write to vbuf in
__get_user_atomic_128_aligned() has the bottom bits of the address
truncated. This results in other local variables being
overwritten. Also vbuf will not contain the correct data which results
in the userspace emulation being wrong and hence undetected user data
corruption.

In the past we've been mostly lucky as vbuf has ended up aligned but
this is fragile and isn't always true. CONFIG_STACKPROTECTOR in
particular can change the stack arrangement enough that our luck runs
out.

This issue only occurs on POWER9 Nimbus <= DD2.1 bare metal.

The fix is to align vbuf to a 16 byte boundary.

Fixes: 5080332c2c89 ("powerpc/64s: Add workaround for P9 vector CI load issue")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201013043741.743413-1-mikey@neuling.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/powermac: Fix low_sleep_handler with KUAP and KUEP 2020-11-05T10:43:31+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2020-09-11T10:29:15+00:00 94e27f13694c04334b8c55e60cfcf1c13e5a5f5d commit 2c637d2df4ee4830e9d3eb2bd5412250522ce96e upstream. low_sleep_handler() has an hardcoded restore of segment registers that doesn't take KUAP and KUEP into account. Use head_32's load_segment_registers() routine instead. Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection") Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/21b05f7298c1b18f73e6e5b4cd5005aafa24b6da.1599820109.git.christophe.leroy@csgroup.eu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2c637d2df4ee4830e9d3eb2bd5412250522ce96e upstream.

low_sleep_handler() has an hardcoded restore of segment registers
that doesn't take KUAP and KUEP into account.

Use head_32's load_segment_registers() routine instead.

Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/21b05f7298c1b18f73e6e5b4cd5005aafa24b6da.1599820109.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc: Warn about use of smt_snooze_delay 2020-11-05T10:43:31+00:00 Joel Stanley joel@jms.id.au 2020-09-02T00:00:11+00:00 3fa03b7f21a3edcee18190c2a4ddccc0b4128dc5 commit a02f6d42357acf6e5de6ffc728e6e77faf3ad217 upstream. It's not done anything for a long time. Save the percpu variable, and emit a warning to remind users to not expect it to do anything. This uses pr_warn_once instead of pr_warn_ratelimit as testing 'ppc64_cpu --smt=off' on a 24 core / 4 SMT system showed the warning to be noisy, as the online/offline loop is slow. Fixes: 3fa8cad82b94 ("powerpc/pseries/cpuidle: smt-snooze-delay cleanup.") Cc: stable@vger.kernel.org # v3.14 Signed-off-by: Joel Stanley <joel@jms.id.au> Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200902000012.3440389-1-joel@jms.id.au Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a02f6d42357acf6e5de6ffc728e6e77faf3ad217 upstream.

It's not done anything for a long time. Save the percpu variable, and
emit a warning to remind users to not expect it to do anything.

This uses pr_warn_once instead of pr_warn_ratelimit as testing
'ppc64_cpu --smt=off' on a 24 core / 4 SMT system showed the warning
to be noisy, as the online/offline loop is slow.

Fixes: 3fa8cad82b94 ("powerpc/pseries/cpuidle: smt-snooze-delay cleanup.")
Cc: stable@vger.kernel.org # v3.14
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902000012.3440389-1-joel@jms.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/rtas: Restrict RTAS requests from userspace 2020-11-05T10:43:30+00:00 Andrew Donnellan ajd@linux.ibm.com 2020-08-20T04:45:12+00:00 240baebeda09e1e010fff58acc9183992f41f638 commit bd59380c5ba4147dcbaad3e582b55ccfd120b764 upstream. A number of userspace utilities depend on making calls to RTAS to retrieve information and update various things. The existing API through which we expose RTAS to userspace exposes more RTAS functionality than we actually need, through the sys_rtas syscall, which allows root (or anyone with CAP_SYS_ADMIN) to make any RTAS call they want with arbitrary arguments. Many RTAS calls take the address of a buffer as an argument, and it's up to the caller to specify the physical address of the buffer as an argument. We allocate a buffer (the "RMO buffer") in the Real Memory Area that RTAS can access, and then expose the physical address and size of this buffer in /proc/powerpc/rtas/rmo_buffer. Userspace is expected to read this address, poke at the buffer using /dev/mem, and pass an address in the RMO buffer to the RTAS call. However, there's nothing stopping the caller from specifying whatever address they want in the RTAS call, and it's easy to construct a series of RTAS calls that can overwrite arbitrary bytes (even without /dev/mem access). Additionally, there are some RTAS calls that do potentially dangerous things and for which there are no legitimate userspace use cases. In the past, this would not have been a particularly big deal as it was assumed that root could modify all system state freely, but with Secure Boot and lockdown we need to care about this. We can't fundamentally change the ABI at this point, however we can address this by implementing a filter that checks RTAS calls against a list of permitted calls and forces the caller to use addresses within the RMO buffer. The list is based off the list of calls that are used by the librtas userspace library, and has been tested with a number of existing userspace RTAS utilities. For compatibility with any applications we are not aware of that require other calls, the filter can be turned off at build time. Cc: stable@vger.kernel.org Reported-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200820044512.7543-1-ajd@linux.ibm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bd59380c5ba4147dcbaad3e582b55ccfd120b764 upstream.

A number of userspace utilities depend on making calls to RTAS to retrieve
information and update various things.

The existing API through which we expose RTAS to userspace exposes more
RTAS functionality than we actually need, through the sys_rtas syscall,
which allows root (or anyone with CAP_SYS_ADMIN) to make any RTAS call they
want with arbitrary arguments.

Many RTAS calls take the address of a buffer as an argument, and it's up to
the caller to specify the physical address of the buffer as an argument. We
allocate a buffer (the "RMO buffer") in the Real Memory Area that RTAS can
access, and then expose the physical address and size of this buffer in
/proc/powerpc/rtas/rmo_buffer. Userspace is expected to read this address,
poke at the buffer using /dev/mem, and pass an address in the RMO buffer to
the RTAS call.

However, there's nothing stopping the caller from specifying whatever
address they want in the RTAS call, and it's easy to construct a series of
RTAS calls that can overwrite arbitrary bytes (even without /dev/mem
access).

Additionally, there are some RTAS calls that do potentially dangerous
things and for which there are no legitimate userspace use cases.

In the past, this would not have been a particularly big deal as it was
assumed that root could modify all system state freely, but with Secure
Boot and lockdown we need to care about this.

We can't fundamentally change the ABI at this point, however we can address
this by implementing a filter that checks RTAS calls against a list
of permitted calls and forces the caller to use addresses within the RMO
buffer.

The list is based off the list of calls that are used by the librtas
userspace library, and has been tested with a number of existing userspace
RTAS utilities. For compatibility with any applications we are not aware of
that require other calls, the filter can be turned off at build time.

Cc: stable@vger.kernel.org
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200820044512.7543-1-ajd@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/tau: Disable TAU between measurements 2020-10-29T08:57:49+00:00 Finn Thain fthain@telegraphics.com.au 2020-09-04T23:02:20+00:00 148d4f4dc75e78c748a72da3d1bd138cea867a80 [ Upstream commit e63d6fb5637e92725cf143559672a34b706bca4f ] Enabling CONFIG_TAU_INT causes random crashes: Unrecoverable exception 1700 at c0009414 (msr=1000) Oops: Unrecoverable exception, sig: 6 [#1] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-pmac-00043-gd5f545e1a8593 #5 NIP: c0009414 LR: c0009414 CTR: c00116fc REGS: c0799eb8 TRAP: 1700 Not tainted (5.7.0-pmac-00043-gd5f545e1a8593) MSR: 00001000 <ME> CR: 22000228 XER: 00000100 GPR00: 00000000 c0799f70 c076e300 00800000 0291c0ac 00e00000 c076e300 00049032 GPR08: 00000001 c00116fc 00000000 dfbd3200 ffffffff 007f80a8 00000000 00000000 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c075ce04 GPR24: c075ce04 dfff8880 c07b0000 c075ce04 00080000 00000001 c079ef98 c079ef5c NIP [c0009414] arch_cpu_idle+0x24/0x6c LR [c0009414] arch_cpu_idle+0x24/0x6c Call Trace: [c0799f70] [00000001] 0x1 (unreliable) [c0799f80] [c0060990] do_idle+0xd8/0x17c [c0799fa0] [c0060ba4] cpu_startup_entry+0x20/0x28 [c0799fb0] [c072d220] start_kernel+0x434/0x44c [c0799ff0] [00003860] 0x3860 Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX 3d20c07b XXXXXXXX XXXXXXXX XXXXXXXX 7c0802a6 XXXXXXXX XXXXXXXX XXXXXXXX 4e800421 XXXXXXXX XXXXXXXX XXXXXXXX 7d2000a6 ---[ end trace 3a0c9b5cb216db6b ]--- Resolve this problem by disabling each THRMn comparator when handling the associated THRMn interrupt and by disabling the TAU entirely when updating THRMn thresholds. Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/5a0ba3dc5612c7aac596727331284a3676c08472.1599260540.git.fthain@telegraphics.com.au Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e63d6fb5637e92725cf143559672a34b706bca4f ]

Enabling CONFIG_TAU_INT causes random crashes:

Unrecoverable exception 1700 at c0009414 (msr=1000)
Oops: Unrecoverable exception, sig: 6 [#1]
BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-pmac-00043-gd5f545e1a8593 #5
NIP:  c0009414 LR: c0009414 CTR: c00116fc
REGS: c0799eb8 TRAP: 1700   Not tainted  (5.7.0-pmac-00043-gd5f545e1a8593)
MSR:  00001000 <ME>  CR: 22000228  XER: 00000100

GPR00: 00000000 c0799f70 c076e300 00800000 0291c0ac 00e00000 c076e300 00049032
GPR08: 00000001 c00116fc 00000000 dfbd3200 ffffffff 007f80a8 00000000 00000000
GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c075ce04
GPR24: c075ce04 dfff8880 c07b0000 c075ce04 00080000 00000001 c079ef98 c079ef5c
NIP [c0009414] arch_cpu_idle+0x24/0x6c
LR [c0009414] arch_cpu_idle+0x24/0x6c
Call Trace:
[c0799f70] [00000001] 0x1 (unreliable)
[c0799f80] [c0060990] do_idle+0xd8/0x17c
[c0799fa0] [c0060ba4] cpu_startup_entry+0x20/0x28
[c0799fb0] [c072d220] start_kernel+0x434/0x44c
[c0799ff0] [00003860] 0x3860
Instruction dump:
XXXXXXXX XXXXXXXX XXXXXXXX 3d20c07b XXXXXXXX XXXXXXXX XXXXXXXX 7c0802a6
XXXXXXXX XXXXXXXX XXXXXXXX 4e800421 XXXXXXXX XXXXXXXX XXXXXXXX 7d2000a6
---[ end trace 3a0c9b5cb216db6b ]---

Resolve this problem by disabling each THRMn comparator when handling
the associated THRMn interrupt and by disabling the TAU entirely when
updating THRMn thresholds.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5a0ba3dc5612c7aac596727331284a3676c08472.1599260540.git.fthain@telegraphics.com.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/tau: Check processor type before enabling TAU interrupt 2020-10-29T08:57:49+00:00 Finn Thain fthain@telegraphics.com.au 2020-09-04T23:02:20+00:00 72407b8d08b359253835d3d3d0604dfcb65bb53f [ Upstream commit 5e3119e15fed5b9a9a7e528665ff098a4a8dbdbc ] According to Freescale's documentation, MPC74XX processors have an erratum that prevents the TAU interrupt from working, so don't try to use it when running on those processors. Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c281611544768e758bd58fe812cf702a5bd2d042.1599260540.git.fthain@telegraphics.com.au Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 5e3119e15fed5b9a9a7e528665ff098a4a8dbdbc ]

According to Freescale's documentation, MPC74XX processors have an
erratum that prevents the TAU interrupt from working, so don't try to
use it when running on those processors.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c281611544768e758bd58fe812cf702a5bd2d042.1599260540.git.fthain@telegraphics.com.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/tau: Remove duplicated set_thresholds() call 2020-10-29T08:57:49+00:00 Finn Thain fthain@telegraphics.com.au 2020-09-04T23:02:20+00:00 68a8ec0b022f2247e46b95f2c5f8eacee8872acf [ Upstream commit 420ab2bc7544d978a5d0762ee736412fe9c796ab ] The commentary at the call site seems to disagree with the code. The conditional prevents calling set_thresholds() via the exception handler, which appears to crash. Perhaps that's because it immediately triggers another TAU exception. Anyway, calling set_thresholds() from TAUupdate() is redundant because tau_timeout() does so. Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/d7c7ee33232cf72a6a6bbb6ef05838b2e2b113c0.1599260540.git.fthain@telegraphics.com.au Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 420ab2bc7544d978a5d0762ee736412fe9c796ab ]

The commentary at the call site seems to disagree with the code. The
conditional prevents calling set_thresholds() via the exception handler,
which appears to crash. Perhaps that's because it immediately triggers
another TAU exception. Anyway, calling set_thresholds() from TAUupdate()
is redundant because tau_timeout() does so.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d7c7ee33232cf72a6a6bbb6ef05838b2e2b113c0.1599260540.git.fthain@telegraphics.com.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/tau: Convert from timer to workqueue 2020-10-29T08:57:49+00:00 Finn Thain fthain@telegraphics.com.au 2020-09-04T23:02:20+00:00 c0578b423b5e1f51b9bc2a9549facc35f25090be [ Upstream commit b1c6a0a10bfaf36ec82fde6f621da72407fa60a1 ] Since commit 19dbdcb8039cf ("smp: Warn on function calls from softirq context") the Thermal Assist Unit driver causes a warning like the following when CONFIG_SMP is enabled. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/smp.c:428 smp_call_function_many_cond+0xf4/0x38c Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-pmac #3 NIP: c00b37a8 LR: c00b3abc CTR: c001218c REGS: c0799c60 TRAP: 0700 Not tainted (5.7.0-pmac) MSR: 00029032 <EE,ME,IR,DR,RI> CR: 42000224 XER: 00000000 GPR00: c00b3abc c0799d18 c076e300 c079ef5c c0011fec 00000000 00000000 00000000 GPR08: 00000100 00000100 00008000 ffffffff 42000224 00000000 c079d040 c079d044 GPR16: 00000001 00000000 00000004 c0799da0 c079f054 c07a0000 c07a0000 00000000 GPR24: c0011fec 00000000 c079ef5c c079ef5c 00000000 00000000 00000000 00000000 NIP [c00b37a8] smp_call_function_many_cond+0xf4/0x38c LR [c00b3abc] on_each_cpu+0x38/0x68 Call Trace: [c0799d18] [ffffffff] 0xffffffff (unreliable) [c0799d68] [c00b3abc] on_each_cpu+0x38/0x68 [c0799d88] [c0096704] call_timer_fn.isra.26+0x20/0x7c [c0799d98] [c0096b40] run_timer_softirq+0x1d4/0x3fc [c0799df8] [c05b4368] __do_softirq+0x118/0x240 [c0799e58] [c0039c44] irq_exit+0xc4/0xcc [c0799e68] [c000ade8] timer_interrupt+0x1b0/0x230 [c0799ea8] [c0013520] ret_from_except+0x0/0x14 --- interrupt: 901 at arch_cpu_idle+0x24/0x6c LR = arch_cpu_idle+0x24/0x6c [c0799f70] [00000001] 0x1 (unreliable) [c0799f80] [c0060990] do_idle+0xd8/0x17c [c0799fa0] [c0060ba8] cpu_startup_entry+0x24/0x28 [c0799fb0] [c072d220] start_kernel+0x434/0x44c [c0799ff0] [00003860] 0x3860 Instruction dump: 8129f204 2f890000 40beff98 3d20c07a 8929eec4 2f890000 40beff88 0fe00000 81220000 552805de 550802ef 4182ff84 <0fe00000> 3860ffff 7f65db78 7f44d378 ---[ end trace 34a886e47819c2eb ]--- Don't call on_each_cpu() from a timer callback, call it from a worker thread instead. Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/bb61650bea4f4c91fb8e24b9a6f130a1438651a7.1599260540.git.fthain@telegraphics.com.au Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b1c6a0a10bfaf36ec82fde6f621da72407fa60a1 ]

Since commit 19dbdcb8039cf ("smp: Warn on function calls from softirq
context") the Thermal Assist Unit driver causes a warning like the
following when CONFIG_SMP is enabled.

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at kernel/smp.c:428 smp_call_function_many_cond+0xf4/0x38c
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-pmac #3
  NIP:  c00b37a8 LR: c00b3abc CTR: c001218c
  REGS: c0799c60 TRAP: 0700   Not tainted  (5.7.0-pmac)
  MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 42000224  XER: 00000000
  GPR00: c00b3abc c0799d18 c076e300 c079ef5c c0011fec 00000000 00000000 00000000
  GPR08: 00000100 00000100 00008000 ffffffff 42000224 00000000 c079d040 c079d044
  GPR16: 00000001 00000000 00000004 c0799da0 c079f054 c07a0000 c07a0000 00000000
  GPR24: c0011fec 00000000 c079ef5c c079ef5c 00000000 00000000 00000000 00000000
  NIP [c00b37a8] smp_call_function_many_cond+0xf4/0x38c
  LR [c00b3abc] on_each_cpu+0x38/0x68
  Call Trace:
  [c0799d18] [ffffffff] 0xffffffff (unreliable)
  [c0799d68] [c00b3abc] on_each_cpu+0x38/0x68
  [c0799d88] [c0096704] call_timer_fn.isra.26+0x20/0x7c
  [c0799d98] [c0096b40] run_timer_softirq+0x1d4/0x3fc
  [c0799df8] [c05b4368] __do_softirq+0x118/0x240
  [c0799e58] [c0039c44] irq_exit+0xc4/0xcc
  [c0799e68] [c000ade8] timer_interrupt+0x1b0/0x230
  [c0799ea8] [c0013520] ret_from_except+0x0/0x14
  --- interrupt: 901 at arch_cpu_idle+0x24/0x6c
      LR = arch_cpu_idle+0x24/0x6c
  [c0799f70] [00000001] 0x1 (unreliable)
  [c0799f80] [c0060990] do_idle+0xd8/0x17c
  [c0799fa0] [c0060ba8] cpu_startup_entry+0x24/0x28
  [c0799fb0] [c072d220] start_kernel+0x434/0x44c
  [c0799ff0] [00003860] 0x3860
  Instruction dump:
  8129f204 2f890000 40beff98 3d20c07a 8929eec4 2f890000 40beff88 0fe00000
  81220000 552805de 550802ef 4182ff84 <0fe00000> 3860ffff 7f65db78 7f44d378
  ---[ end trace 34a886e47819c2eb ]---

Don't call on_each_cpu() from a timer callback, call it from a worker
thread instead.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bb61650bea4f4c91fb8e24b9a6f130a1438651a7.1599260540.git.fthain@telegraphics.com.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/tau: Use appropriate temperature sample interval 2020-10-29T08:57:49+00:00 Finn Thain fthain@telegraphics.com.au 2020-09-04T23:02:20+00:00 0305488040dce95feb8705e1e0270a7df04860e2 [ Upstream commit 66943005cc41f48e4d05614e8f76c0ca1812f0fd ] According to the MPC750 Users Manual, the SITV value in Thermal Management Register 3 is 13 bits long. The present code calculates the SITV value as 60 * 500 cycles. This would overflow to give 10 us on a 500 MHz CPU rather than the intended 60 us. (But according to the Microprocessor Datasheet, there is also a factor of 266 that has to be applied to this value on certain parts i.e. speed sort above 266 MHz.) Always use the maximum cycle count, as recommended by the Datasheet. Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/896f542e5f0f1d6cf8218524c2b67d79f3d69b3c.1599260540.git.fthain@telegraphics.com.au Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 66943005cc41f48e4d05614e8f76c0ca1812f0fd ]

According to the MPC750 Users Manual, the SITV value in Thermal
Management Register 3 is 13 bits long. The present code calculates the
SITV value as 60 * 500 cycles. This would overflow to give 10 us on
a 500 MHz CPU rather than the intended 60 us. (But according to the
Microprocessor Datasheet, there is also a factor of 266 that has to be
applied to this value on certain parts i.e. speed sort above 266 MHz.)
Always use the maximum cycle count, as recommended by the Datasheet.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/896f542e5f0f1d6cf8218524c2b67d79f3d69b3c.1599260540.git.fthain@telegraphics.com.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/traps: Make unrecoverable NMIs die instead of panic 2020-10-01T11:18:01+00:00 Nicholas Piggin npiggin@gmail.com 2020-05-08T04:34:07+00:00 7c972122cab5173ec8eb4379e2f50cf0bfa0e8b1 [ Upstream commit 265d6e588d87194c2fe2d6c240247f0264e0c19b ] System Reset and Machine Check interrupts that are not recoverable due to being nested or interrupting when RI=0 currently panic. This is not necessary, and can often just kill the current context and recover. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Link: https://lore.kernel.org/r/20200508043408.886394-16-npiggin@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 265d6e588d87194c2fe2d6c240247f0264e0c19b ]

System Reset and Machine Check interrupts that are not recoverable due
to being nested or interrupting when RI=0 currently panic. This is not
necessary, and can often just kill the current context and recover.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Link: https://lore.kernel.org/r/20200508043408.886394-16-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>