linux-stable.git/arch/powerpc/kernel/interrupt.c, branch linux-5.15.y Linux kernel stable tree powerpc/32s: Do kuep_lock() and kuep_unlock() in assembly 2023-10-25T09:58:59+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2021-10-19T07:29:17+00:00 558ee0fafd404dfbcef864945310b9a98d459678 [ Upstream commit 526d4a4c77aedf1b7df1133e5cced29c70232e6e ] When interrupt and syscall entries where converted to C, KUEP locking and unlocking was also converted. It improved performance by unrolling the loop, and allowed easily implementing boot time deactivation of KUEP. However, null_syscall selftest shows that KUEP is still heavy (361 cycles with KUEP, 212 cycles without). A way to improve more is to group 'mtsr's together, instead of repeating 'addi' + 'mtsr' several times. In order to do that, more registers need to be available. In C, GCC will always be able to provide the requested number of registers, but at the cost of saving some data on the stack, which is counter performant here. So let's do it in assembly, when we have full control of which register can be used. It also has the advantage of locking earlier and unlocking later and it helps GCC generating less tricky code. The only drawback is to make boot time deactivation less straight forward and require 'hand' instruction patching. Group 'mtsr's by 4. With this change, null_syscall selftest reports 336 cycles. Without the change it was 361 cycles, that's a 7% reduction. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/115cb279e9b9948dfd93a065e047081c59e3a2a6.1634627931.git.christophe.leroy@csgroup.eu Stable-dep-of: f0eee815babe ("powerpc/47x: Fix 47x syscall return crash") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 526d4a4c77aedf1b7df1133e5cced29c70232e6e ]

When interrupt and syscall entries where converted to C, KUEP locking
and unlocking was also converted. It improved performance by unrolling
the loop, and allowed easily implementing boot time deactivation of
KUEP.

However, null_syscall selftest shows that KUEP is still heavy
(361 cycles with KUEP, 212 cycles without).

A way to improve more is to group 'mtsr's together, instead of
repeating 'addi' + 'mtsr' several times.

In order to do that, more registers need to be available. In C, GCC
will always be able to provide the requested number of registers, but
at the cost of saving some data on the stack, which is counter
performant here.

So let's do it in assembly, when we have full control of which
register can be used. It also has the advantage of locking earlier
and unlocking later and it helps GCC generating less tricky code.
The only drawback is to make boot time deactivation less straight
forward and require 'hand' instruction patching.

Group 'mtsr's by 4.

With this change, null_syscall selftest reports 336 cycles. Without
the change it was 361 cycles, that's a 7% reduction.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/115cb279e9b9948dfd93a065e047081c59e3a2a6.1634627931.git.christophe.leroy@csgroup.eu
Stable-dep-of: f0eee815babe ("powerpc/47x: Fix 47x syscall return crash")
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare() 2023-07-23T11:47:12+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2023-06-05T08:55:26+00:00 7d25fc45c42cd32f90eaa0b8cb44631a525b934b [ Upstream commit 0eb089a72fda3f7969e6277804bde75dc1474a14 ] A disassembly of interrupt_exit_kernel_prepare() shows a useless read of MSR register. This is shown by r9 being re-used immediately without doing anything with the value read. c000e0e0: 60 00 00 00 nop c000e0e4: 7d 3a c2 a6 mfmd_ap r9 c000e0e8: 7d 20 00 a6 mfmsr r9 c000e0ec: 7c 51 13 a6 mtspr 81,r2 c000e0f0: 81 3f 00 84 lwz r9,132(r31) c000e0f4: 71 29 80 00 andi. r9,r9,32768 This is due to the use of local_irq_save(). The flags read by local_irq_save() are never used, use local_irq_disable() instead. Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0eb089a72fda3f7969e6277804bde75dc1474a14 ]

A disassembly of interrupt_exit_kernel_prepare() shows a useless read
of MSR register. This is shown by r9 being re-used immediately without
doing anything with the value read.

  c000e0e0:       60 00 00 00     nop
  c000e0e4:       7d 3a c2 a6     mfmd_ap r9
  c000e0e8:       7d 20 00 a6     mfmsr   r9
  c000e0ec:       7c 51 13 a6     mtspr   81,r2
  c000e0f0:       81 3f 00 84     lwz     r9,132(r31)
  c000e0f4:       71 29 80 00     andi.   r9,r9,32768

This is due to the use of local_irq_save(). The flags read by
local_irq_save() are never used, use local_irq_disable() instead.

Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/64s/interrupt: Fix interrupt exit race with security mitigation switch 2023-02-14T18:18:03+00:00 Nicholas Piggin npiggin@gmail.com 2023-02-06T04:22:40+00:00 86f7e423933608d536015a0f2eb9e0338c1227e0 commit 2ea31e2e62bbc4d11c411eeb36f1b02841dbcab1 upstream. The RFI and STF security mitigation options can flip the interrupt_exit_not_reentrant static branch condition concurrently with the interrupt exit code which tests that branch. Interrupt exit tests this condition to set MSR[EE|RI] for exit, then again in the case a soft-masked interrupt is found pending, to recover the MSR so the interrupt can be replayed before attempting to exit again. If the condition changes between these two tests, the MSR and irq soft-mask state will become corrupted, leading to warnings and possible crashes. For example, if the branch is initially true then false, MSR[EE] will be 0 but PACA_IRQ_HARD_DIS clear and EE may not get enabled, leading to warnings in irq_64.c. Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt") Cc: stable@vger.kernel.org # v5.14+ Reported-by: Sachin Sant <sachinp@linux.ibm.com> Tested-by: Sachin Sant <sachinp@linux.ibm.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230206042240.92103-1-npiggin@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2ea31e2e62bbc4d11c411eeb36f1b02841dbcab1 upstream.

The RFI and STF security mitigation options can flip the
interrupt_exit_not_reentrant static branch condition concurrently with
the interrupt exit code which tests that branch.

Interrupt exit tests this condition to set MSR[EE|RI] for exit, then
again in the case a soft-masked interrupt is found pending, to recover
the MSR so the interrupt can be replayed before attempting to exit
again. If the condition changes between these two tests, the MSR and irq
soft-mask state will become corrupted, leading to warnings and possible
crashes. For example, if the branch is initially true then false,
MSR[EE] will be 0 but PACA_IRQ_HARD_DIS clear and EE may not get
enabled, leading to warnings in irq_64.c.

Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230206042240.92103-1-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc: Avoid discarding flags in system_call_exception() 2022-01-27T10:03:22+00:00 Mark Rutland mark.rutland@arm.com 2021-11-29T13:06:51+00:00 0c1cf578a8822cc1a92c955b87a4b2cd27caed9a [ Upstream commit 08b0af5b2affbe7419853e8dd1330e4b3fe27125 ] Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Thus, when setting flags we must use an atomic operation rather than a plain read-modify-write sequence, as a plain read-modify-write may discard flags which are concurrently set by a remote thread, e.g. // task A // task B tmp = A->thread_info.flags; set_tsk_thread_flag(A, NEWFLAG_B); tmp |= NEWFLAG_A; A->thread_info.flags = tmp; arch/powerpc/kernel/interrupt.c's system_call_exception() sets _TIF_RESTOREALL in the thread info flags with a read-modify-write, which may result in other flags being discarded. Elsewhere in the file it uses clear_bits() to atomically remove flag bits, so use set_bits() here for consistency with those. There may be reasons (e.g. instrumentation) that prevent the use of set_thread_flag() and clear_thread_flag() here, which would otherwise be preferable. Fixes: ae7aaecc3f2f78b7 ("powerpc/64s: system call rfscv workaround for TM bugs") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Eirik Fuller <efuller@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Link: https://lore.kernel.org/r/20211129130653.2037928-10-mark.rutland@arm.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 08b0af5b2affbe7419853e8dd1330e4b3fe27125 ]

Some thread flags can be set remotely, and so even when IRQs are disabled,
the flags can change under our feet. Thus, when setting flags we must use
an atomic operation rather than a plain read-modify-write sequence, as a
plain read-modify-write may discard flags which are concurrently set by a
remote thread, e.g.

	// task A			// task B
	tmp = A->thread_info.flags;
					set_tsk_thread_flag(A, NEWFLAG_B);
	tmp |= NEWFLAG_A;
	A->thread_info.flags = tmp;

arch/powerpc/kernel/interrupt.c's system_call_exception() sets
_TIF_RESTOREALL in the thread info flags with a read-modify-write, which
may result in other flags being discarded.

Elsewhere in the file it uses clear_bits() to atomically remove flag bits,
so use set_bits() here for consistency with those.

There may be reasons (e.g. instrumentation) that prevent the use of
set_thread_flag() and clear_thread_flag() here, which would otherwise be
preferable.

Fixes: ae7aaecc3f2f78b7 ("powerpc/64s: system call rfscv workaround for TM bugs")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Eirik Fuller <efuller@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/r/20211129130653.2037928-10-mark.rutland@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
powerpc/64s/interrupt: Fix check_return_regs_valid() false positive 2021-11-18T18:17:19+00:00 Nicholas Piggin npiggin@gmail.com 2021-10-26T12:25:31+00:00 d05dc4bdc3332b487fcda21f70eb70ad42c2e2cc commit 4a5cb51f3db4be547225a4bce7a43d41b231382b upstream. The check_return_regs_valid() can cause a false positive if the return regs are marked as norestart and they are an HSRR type interrupt, because the low bit in the bottom of regs->trap causes interrupt type matching to fail. This can occcur for example on bare metal with a HV privileged doorbell interrupt that causes a signal, but do_signal returns early because get_signal() fails, and takes the "No signal to deliver" path. In this case no signal was delivered so the return location is not changed so return SRRs are not invalidated, yet set_trap_norestart is called, which messes up the match. Building go-1.16.6 is known to reproduce this. Fix it by using the TRAP() accessor which masks out the low bit. Fixes: 6eaaf9de3599 ("powerpc/64s/interrupt: Check and fix srr_valid without crashing") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211026122531.3599918-1-npiggin@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4a5cb51f3db4be547225a4bce7a43d41b231382b upstream.

The check_return_regs_valid() can cause a false positive if the return
regs are marked as norestart and they are an HSRR type interrupt,
because the low bit in the bottom of regs->trap causes interrupt type
matching to fail.

This can occcur for example on bare metal with a HV privileged doorbell
interrupt that causes a signal, but do_signal returns early because
get_signal() fails, and takes the "No signal to deliver" path. In this
case no signal was delivered so the return location is not changed so
return SRRs are not invalidated, yet set_trap_norestart is called, which
messes up the match. Building go-1.16.6 is known to reproduce this.

Fix it by using the TRAP() accessor which masks out the low bit.

Fixes: 6eaaf9de3599 ("powerpc/64s/interrupt: Check and fix srr_valid without crashing")
Cc: stable@vger.kernel.org # v5.14+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211026122531.3599918-1-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/64s: system call rfscv workaround for TM bugs 2021-09-13T12:34:11+00:00 Nicholas Piggin npiggin@gmail.com 2021-09-08T10:17:17+00:00 ae7aaecc3f2f78b76ab3a8d6178610f55aadfa56 The rfscv instruction does not work correctly with the fake-suspend mode in POWER9, which can end up with the hypervisor restoring an incorrect checkpoint. Work around this by setting the _TIF_RESTOREALL flag if a system call returns to a transaction active state, causing rfid to be used instead of rfscv to return, which will do the right thing. The contents of the registers are irrelevant because they will be overwritten in this case anyway. Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv instructions") Reported-by: Eirik Fuller <efuller@redhat.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210908101718.118522-1-npiggin@gmail.com 
The rfscv instruction does not work correctly with the fake-suspend mode
in POWER9, which can end up with the hypervisor restoring an incorrect
checkpoint.

Work around this by setting the _TIF_RESTOREALL flag if a system call
returns to a transaction active state, causing rfid to be used instead
of rfscv to return, which will do the right thing. The contents of the
registers are irrelevant because they will be overwritten in this case
anyway.

Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv instructions")
Reported-by: Eirik Fuller <efuller@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210908101718.118522-1-npiggin@gmail.com
powerpc/64s: system call scv tabort fix for corrupt irq soft-mask state 2021-09-13T12:34:11+00:00 Nicholas Piggin npiggin@gmail.com 2021-09-03T12:57:06+00:00 b871895b148256f1721bc565d803860242755a0b If a system call is made with a transaction active, the kernel immediately aborts it and returns. scv system calls disable irqs even earlier in their interrupt handler, and tabort_syscall does not fix this up. This can result in irq soft-mask state being messed up on the next kernel entry, and crashing at BUG_ON(arch_irq_disabled_regs(regs)) in the kernel exit handlers, or possibly worse. This can't easily be fixed in asm because at this point an async irq may have hit, which is soft-masked and marked pending. The pending interrupt has to be replayed before returning to userspace. The fix is to move the tabort_syscall code to C in the main syscall handler, and just skip the system call but otherwise return as usual, which will take care of the pending irqs. This also does a bunch of other things including possible signal delivery to the process, but the doomed transaction should still be aborted when it is eventually returned to. The sc system call path is changed to use the new C function as well to reduce code and path differences. This slows down how quickly system calls are aborted when called while a transaction is active, which could potentially impact TM performance. But making any system call is already bad for performance, and TM is on the way out, so go with simpler over faster. Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv instructions") Reported-by: Eirik Fuller <efuller@redhat.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Use #ifdef rather than IS_ENABLED() to fix build error on 32-bit] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210903125707.1601269-1-npiggin@gmail.com 
If a system call is made with a transaction active, the kernel
immediately aborts it and returns. scv system calls disable irqs even
earlier in their interrupt handler, and tabort_syscall does not fix this
up.

This can result in irq soft-mask state being messed up on the next
kernel entry, and crashing at BUG_ON(arch_irq_disabled_regs(regs)) in
the kernel exit handlers, or possibly worse.

This can't easily be fixed in asm because at this point an async irq may
have hit, which is soft-masked and marked pending. The pending interrupt
has to be replayed before returning to userspace. The fix is to move the
tabort_syscall code to C in the main syscall handler, and just skip the
system call but otherwise return as usual, which will take care of the
pending irqs. This also does a bunch of other things including possible
signal delivery to the process, but the doomed transaction should still
be aborted when it is eventually returned to.

The sc system call path is changed to use the new C function as well to
reduce code and path differences. This slows down how quickly system
calls are aborted when called while a transaction is active, which could
potentially impact TM performance. But making any system call is already
bad for performance, and TM is on the way out, so go with simpler over
faster.

Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv instructions")
Reported-by: Eirik Fuller <efuller@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Use #ifdef rather than IS_ENABLED() to fix build error on 32-bit]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210903125707.1601269-1-npiggin@gmail.com
powerpc: Refactor verification of MSR_RI 2021-08-26T11:21:07+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2021-08-23T08:24:21+00:00 806c0e6e7e97adc17389c8dc1f52d4736f49299b 40x and BOOKE don't have MSR_RI therefore all tests involving MSR_RI may be problematic on those plateforms. Create helpers to check or set MSR_RI in regs, and use them in common code. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c2fb93708196734f4176dda334aaa3055f213b89.1629707037.git.christophe.leroy@csgroup.eu 
40x and BOOKE don't have MSR_RI therefore all tests involving
MSR_RI may be problematic on those plateforms.

Create helpers to check or set MSR_RI in regs, and use them
in common code.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c2fb93708196734f4176dda334aaa3055f213b89.1629707037.git.christophe.leroy@csgroup.eu
powerpc: Remove MSR_PR check in interrupt_exit_{user/kernel}_prepare() 2021-08-26T11:21:07+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2021-08-23T08:24:20+00:00 133c17a1788d68c9fff59d5f724a4ba14647a16d In those hot functions that are called at every interrupt, any saved cycle is worth it. interrupt_exit_user_prepare() and interrupt_exit_kernel_prepare() are called from three places: - From entry_32.S - From interrupt_64.S - From interrupt_exit_user_restart() and interrupt_exit_kernel_restart() In entry_32.S, there are inambiguously called based on MSR_PR: interrupt_return: lwz r4,_MSR(r1) addi r3,r1,STACK_FRAME_OVERHEAD andi. r0,r4,MSR_PR beq .Lkernel_interrupt_return bl interrupt_exit_user_prepare ... .Lkernel_interrupt_return: bl interrupt_exit_kernel_prepare In interrupt_64.S, that's similar: interrupt_return_\srr\(): ld r4,_MSR(r1) andi. r0,r4,MSR_PR beq interrupt_return_\srr\()_kernel interrupt_return_\srr\()_user: /* make backtraces match the _kernel variant */ addi r3,r1,STACK_FRAME_OVERHEAD bl interrupt_exit_user_prepare ... interrupt_return_\srr\()_kernel: addi r3,r1,STACK_FRAME_OVERHEAD bl interrupt_exit_kernel_prepare In interrupt_exit_user_restart() and interrupt_exit_kernel_restart(), MSR_PR is verified respectively by BUG_ON(!user_mode(regs)) and BUG_ON(user_mode(regs)) prior to calling interrupt_exit_user_prepare() and interrupt_exit_kernel_prepare(). The verification in interrupt_exit_user_prepare() and interrupt_exit_kernel_prepare() are therefore useless and can be removed. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/385ead49ccb66a259b25fee3eebf0bd4094068f3.1629707037.git.christophe.leroy@csgroup.eu 
In those hot functions that are called at every interrupt, any saved
cycle is worth it.

interrupt_exit_user_prepare() and interrupt_exit_kernel_prepare() are
called from three places:
- From entry_32.S
- From interrupt_64.S
- From interrupt_exit_user_restart() and interrupt_exit_kernel_restart()

In entry_32.S, there are inambiguously called based on MSR_PR:

	interrupt_return:
		lwz	r4,_MSR(r1)
		addi	r3,r1,STACK_FRAME_OVERHEAD
		andi.	r0,r4,MSR_PR
		beq	.Lkernel_interrupt_return
		bl	interrupt_exit_user_prepare
	...
	.Lkernel_interrupt_return:
		bl	interrupt_exit_kernel_prepare

In interrupt_64.S, that's similar:

	interrupt_return_\srr\():
		ld	r4,_MSR(r1)
		andi.	r0,r4,MSR_PR
		beq	interrupt_return_\srr\()_kernel
	interrupt_return_\srr\()_user: /* make backtraces match the _kernel variant */
		addi	r3,r1,STACK_FRAME_OVERHEAD
		bl	interrupt_exit_user_prepare
	...
	interrupt_return_\srr\()_kernel:
		addi	r3,r1,STACK_FRAME_OVERHEAD
		bl	interrupt_exit_kernel_prepare

In interrupt_exit_user_restart() and interrupt_exit_kernel_restart(),
MSR_PR is verified respectively by BUG_ON(!user_mode(regs)) and
BUG_ON(user_mode(regs)) prior to calling interrupt_exit_user_prepare()
and interrupt_exit_kernel_prepare().

The verification in interrupt_exit_user_prepare() and
interrupt_exit_kernel_prepare() are therefore useless and can be removed.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/385ead49ccb66a259b25fee3eebf0bd4094068f3.1629707037.git.christophe.leroy@csgroup.eu
powerpc: Remove duplicate includes 2021-08-17T23:25:23+00:00 Wan Jiabing wanjiabing@vivo.com 2021-03-23T06:29:05+00:00 e225c4d6bc389701f2f63fc246420a1da3465ab5 interrupt.c: asm/interrupt.h has been included at line 12, so remove the duplicate one at line 10. time.c: linux/sched/clock.h has been included at line 33,so remove the duplicate one at line 56 and move sched/cputime.h under sched including segament. Signed-off-by: Wan Jiabing <wanjiabing@vivo.com> Reviewed-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210323062916.295346-1-wanjiabing@vivo.com 
interrupt.c: asm/interrupt.h has been included at line 12, so remove the
duplicate one at line 10.

time.c: linux/sched/clock.h has been included at line 33,so remove the
duplicate one at line 56 and move sched/cputime.h under sched including
segament.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210323062916.295346-1-wanjiabing@vivo.com