linux.git/arch/powerpc/kernel, branch v5.11 Linux kernel source tree powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics 2021-02-02T11:14:41+00:00 Raoni Fassina Firmino raoni@linux.ibm.com 2021-02-01T20:05:05+00:00 24321ac668e452a4942598533d267805f291fdc9 Commit 0138ba5783ae ("powerpc/64/signal: Balance return predictor stack in signal trampoline") changed __kernel_sigtramp_rt64() VDSO and trampoline code, and introduced a regression in the way glibc's backtrace()[1] detects the signal-handler stack frame. Apart from the practical implications, __kernel_sigtramp_rt64() was a VDSO function with the semantics that it is a function you can call from userspace to end a signal handling. Now this semantics are no longer valid. I believe the aforementioned change affects all releases since 5.9. This patch tries to fix both the semantics and practical aspect of __kernel_sigtramp_rt64() returning it to the previous code, whilst keeping the intended behaviour of 0138ba5783ae by adding a new symbol to serve as the jump target from the kernel to the trampoline. Now the trampoline has two parts, a new entry point and the old return point. [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223194.html Fixes: 0138ba5783ae ("powerpc/64/signal: Balance return predictor stack in signal trampoline") Cc: stable@vger.kernel.org # v5.9+ Signed-off-by: Raoni Fassina Firmino <raoni@linux.ibm.com> Acked-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Minor tweaks to change log formatting, add stable tag] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210201200505.iz46ubcizipnkcxe@work-tp 
Commit 0138ba5783ae ("powerpc/64/signal: Balance return predictor
stack in signal trampoline") changed __kernel_sigtramp_rt64() VDSO and
trampoline code, and introduced a regression in the way glibc's
backtrace()[1] detects the signal-handler stack frame. Apart from the
practical implications, __kernel_sigtramp_rt64() was a VDSO function
with the semantics that it is a function you can call from userspace
to end a signal handling. Now this semantics are no longer valid.

I believe the aforementioned change affects all releases since 5.9.

This patch tries to fix both the semantics and practical aspect of
__kernel_sigtramp_rt64() returning it to the previous code, whilst
keeping the intended behaviour of 0138ba5783ae by adding a new symbol
to serve as the jump target from the kernel to the trampoline. Now the
trampoline has two parts, a new entry point and the old return point.

[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223194.html

Fixes: 0138ba5783ae ("powerpc/64/signal: Balance return predictor stack in signal trampoline")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Raoni Fassina Firmino <raoni@linux.ibm.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Minor tweaks to change log formatting, add stable tag]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210201200505.iz46ubcizipnkcxe@work-tp
powerpc/vdso64: remove meaningless vgettimeofday.o build rule 2021-01-30T11:23:42+00:00 Masahiro Yamada masahiroy@kernel.org 2020-12-23T17:11:42+00:00 66f0a9e058fad50e569ad752be72e52701991fd5 VDSO64 is only built for the 64-bit kernel, hence vgettimeofday.o is built by the generic rule in scripts/Makefile.build. This line does not provide anything useful. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201223171142.707053-2-masahiroy@kernel.org 
VDSO64 is only built for the 64-bit kernel, hence vgettimeofday.o is
built by the generic rule in scripts/Makefile.build.

This line does not provide anything useful.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201223171142.707053-2-masahiroy@kernel.org
powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o 2021-01-30T11:23:42+00:00 Masahiro Yamada masahiroy@kernel.org 2020-12-23T17:11:41+00:00 bce74491c3008e27dd6e8f79a83b4faa77a08f7e vgettimeofday.o is unnecessarily rebuilt. Adding it to 'targets' is not enough to fix the issue. Kbuild is correctly rebuilding it because the command line is changed. PowerPC builds each vdso directory twice; first in vdso_prepare to generate vdso{32,64}-offsets.h, second as part of the ordinary build process to embed vdso{32,64}.so.dbg into the kernel. The problem shows up when CONFIG_PPC_WERROR=y due to the following line in arch/powerpc/Kbuild: subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror In the preparation stage, Kbuild directly visits the vdso directories, hence it does not inherit subdir-ccflags-y. In the second descend, Kbuild adds -Werror, which results in the command line flipping with/without -Werror. It implies a potential danger; if a more critical flag that would impact the resulted vdso, the offsets recorded in the headers might be different from real offsets in the embedded vdso images. Removing the unneeded second descend solves the problem. Reported-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/linuxppc-dev/87tuslxhry.fsf@mpe.ellerman.id.au/ Link: https://lore.kernel.org/r/20201223171142.707053-1-masahiroy@kernel.org 
vgettimeofday.o is unnecessarily rebuilt. Adding it to 'targets' is not
enough to fix the issue. Kbuild is correctly rebuilding it because the
command line is changed.

PowerPC builds each vdso directory twice; first in vdso_prepare to
generate vdso{32,64}-offsets.h, second as part of the ordinary build
process to embed vdso{32,64}.so.dbg into the kernel.

The problem shows up when CONFIG_PPC_WERROR=y due to the following line
in arch/powerpc/Kbuild:

  subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror

In the preparation stage, Kbuild directly visits the vdso directories,
hence it does not inherit subdir-ccflags-y. In the second descend,
Kbuild adds -Werror, which results in the command line flipping
with/without -Werror.

It implies a potential danger; if a more critical flag that would impact
the resulted vdso, the offsets recorded in the headers might be different
from real offsets in the embedded vdso images.

Removing the unneeded second descend solves the problem.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/linuxppc-dev/87tuslxhry.fsf@mpe.ellerman.id.au/
Link: https://lore.kernel.org/r/20201223171142.707053-1-masahiroy@kernel.org
powerpc/64s: prevent recursive replay_soft_interrupts causing superfluous interrupt 2021-01-24T11:27:24+00:00 Nicholas Piggin npiggin@gmail.com 2021-01-23T06:12:44+00:00 4025c784c573cab7e3f84746cc82b8033923ec62 When an asynchronous interrupt calls irq_exit, it checks for softirqs that may have been created, and runs them. Running softirqs enables local irqs, which can replay pending interrupts causing recursion in replay_soft_interrupts. This abridged trace shows how this can occur: ! NIP replay_soft_interrupts LR interrupt_exit_kernel_prepare Call Trace: interrupt_exit_kernel_prepare (unreliable) interrupt_return --- interrupt: ea0 at __rb_reserve_next NIP __rb_reserve_next LR __rb_reserve_next Call Trace: ring_buffer_lock_reserve trace_function function_trace_call ftrace_call __do_softirq irq_exit timer_interrupt ! replay_soft_interrupts interrupt_exit_kernel_prepare interrupt_return --- interrupt: ea0 at arch_local_irq_restore This can not be prevented easily, because softirqs must not block hard irqs, so it has to be dealt with. The recursion is bounded by design in the softirq code because softirq replay disables softirqs and loops around again to check for new softirqs created while it ran, so that's not a problem. However it does mess up interrupt replay state, causing superfluous interrupts when the second replay_soft_interrupts clears a pending interrupt, leaving it still set in the first call in the 'happened' local variable. Fix this by not caching a copy of irqs_happened across interrupt handler calls. Fixes: 3282a3da25bd ("powerpc/64: Implement soft interrupt replay in C") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210123061244.2076145-1-npiggin@gmail.com 
When an asynchronous interrupt calls irq_exit, it checks for softirqs
that may have been created, and runs them. Running softirqs enables
local irqs, which can replay pending interrupts causing recursion in
replay_soft_interrupts. This abridged trace shows how this can occur:

! NIP replay_soft_interrupts
  LR  interrupt_exit_kernel_prepare
  Call Trace:
    interrupt_exit_kernel_prepare (unreliable)
    interrupt_return
  --- interrupt: ea0 at __rb_reserve_next
  NIP __rb_reserve_next
  LR __rb_reserve_next
  Call Trace:
    ring_buffer_lock_reserve
    trace_function
    function_trace_call
    ftrace_call
    __do_softirq
    irq_exit
    timer_interrupt
!   replay_soft_interrupts
    interrupt_exit_kernel_prepare
    interrupt_return
  --- interrupt: ea0 at arch_local_irq_restore

This can not be prevented easily, because softirqs must not block hard
irqs, so it has to be dealt with.

The recursion is bounded by design in the softirq code because softirq
replay disables softirqs and loops around again to check for new
softirqs created while it ran, so that's not a problem.

However it does mess up interrupt replay state, causing superfluous
interrupts when the second replay_soft_interrupts clears a pending
interrupt, leaving it still set in the first call in the 'happened'
local variable.

Fix this by not caching a copy of irqs_happened across interrupt
handler calls.

Fixes: 3282a3da25bd ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210123061244.2076145-1-npiggin@gmail.com
powerpc/64s: fix scv entry fallback flush vs interrupt 2021-01-20T04:58:19+00:00 Nicholas Piggin npiggin@gmail.com 2021-01-11T06:24:08+00:00 08685be7761d69914f08c3d6211c543a385a5b9c The L1D flush fallback functions are not recoverable vs interrupts, yet the scv entry flush runs with MSR[EE]=1. This can result in a timer (soft-NMI) or MCE or SRESET interrupt hitting here and overwriting the EXRFI save area, which ends up corrupting userspace registers for scv return. Fix this by disabling RI and EE for the scv entry fallback flush. Fixes: f79643787e0a0 ("powerpc/64s: flush L1D on kernel entry") Cc: stable@vger.kernel.org # 5.9+ which also have flush L1D patch backport Reported-by: Tulio Magno Quites Machado Filho <tuliom@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/20210111062408.287092-1-npiggin@gmail.com 
The L1D flush fallback functions are not recoverable vs interrupts,
yet the scv entry flush runs with MSR[EE]=1. This can result in a
timer (soft-NMI) or MCE or SRESET interrupt hitting here and overwriting
the EXRFI save area, which ends up corrupting userspace registers for
scv return.

Fix this by disabling RI and EE for the scv entry fallback flush.

Fixes: f79643787e0a0 ("powerpc/64s: flush L1D on kernel entry")
Cc: stable@vger.kernel.org # 5.9+ which also have flush L1D patch backport
Reported-by: Tulio Magno Quites Machado Filho <tuliom@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/20210111062408.287092-1-npiggin@gmail.com
powerpc: Fix alignment bug within the init sections 2021-01-12T04:06:23+00:00 Ariel Marcovitch arielmarcovitch@gmail.com 2021-01-02T20:11:56+00:00 2225a8dda263edc35a0e8b858fe2945cf6240fde This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch@gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com 
This is a bug that causes early crashes in builds with an .exit.text
section smaller than a page and an .init.text section that ends in the
beginning of a physical page (this is kinda random, which might
explain why this wasn't really encountered before).

The init sections are ordered like this:
  .init.text
  .exit.text
  .init.data

Currently, these sections aren't page aligned.

Because the init code might become read-only at runtime and because
the .init.text section can potentially reside on the same physical
page as .init.data, the beginning of .init.data might be mapped
read-only along with .init.text.

Then when the kernel tries to modify a variable in .init.data (like
kthreadd_done, used in kernel_init()) the kernel panics.

To avoid this, make _einittext page aligned and also align .exit.text
to make sure .init.data is always seperated from the text segments.

Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext")
Signed-off-by: Ariel Marcovitch <ariel.marcovitch@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com
powerpc: Handle .text.{hot,unlikely}.* in linker script 2021-01-06T10:59:04+00:00 Nathan Chancellor natechancellor@gmail.com 2021-01-04T20:59:53+00:00 3ce47d95b7346dcafd9bed3556a8d072cb2b8571 Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1]. After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure: $ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.' ... ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256) ... ERROR: start_text address is c000000000009400, should be c000000000008000 ERROR: try to enable LD_HEAD_STUB_CATCH config option ERROR: see comments in arch/powerpc/tools/head_check.sh ... Explicitly handle these sections like in the main linker script so there is no more build failure. [1]: https://reviews.llvm.org/D79600 [2]: https://reviews.llvm.org/D92493 Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Cc: stable@vger.kernel.org Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://github.com/ClangBuiltLinux/linux/issues/1218 Link: https://lore.kernel.org/r/20210104205952.1399409-1-natechancellor@gmail.com 
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input
sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM
change [1].

After another LLVM change [2], these sections are seen in some PowerPC
builds, where there is a orphan section warning then build failure:

$ make -skj"$(nproc)" \
       ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \
       distclean powernv_defconfig zImage.epapr
ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'
...
ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256)
...
ERROR: start_text address is c000000000009400, should be c000000000008000
ERROR: try to enable LD_HEAD_STUB_CATCH config option
ERROR: see comments in arch/powerpc/tools/head_check.sh
...

Explicitly handle these sections like in the main linker script so
there is no more build failure.

[1]: https://reviews.llvm.org/D79600
[2]: https://reviews.llvm.org/D92493

Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections")
Cc: stable@vger.kernel.org
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1218
Link: https://lore.kernel.org/r/20210104205952.1399409-1-natechancellor@gmail.com
powerpc/32s: Fix RTAS machine check with VMAP stack 2021-01-04T12:59:25+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2020-12-22T07:11:18+00:00 98bf2d3f4970179c702ef64db658e0553bc6ef3a When we have VMAP stack, exception prolog 1 sets r1, not r11. When it is not an RTAS machine check, don't trash r1 because it is needed by prolog 1. Fixes: da7bb43ab9da ("powerpc/32: Fix vmap stack - Properly set r1 before activating MMU") Fixes: d2e006036082 ("powerpc/32: Use SPRN_SPRG_SCRATCH2 in exception prologs") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> [mpe: Squash in fixup for RTAS machine check from Christophe] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/bc77d61d1c18940e456a2dee464f1e2eda65a3f0.1608621048.git.christophe.leroy@csgroup.eu 
When we have VMAP stack, exception prolog 1 sets r1, not r11.

When it is not an RTAS machine check, don't trash r1 because it is
needed by prolog 1.

Fixes: da7bb43ab9da ("powerpc/32: Fix vmap stack - Properly set r1 before activating MMU")
Fixes: d2e006036082 ("powerpc/32: Use SPRN_SPRG_SCRATCH2 in exception prologs")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Squash in fixup for RTAS machine check from Christophe]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bc77d61d1c18940e456a2dee464f1e2eda65a3f0.1608621048.git.christophe.leroy@csgroup.eu
Merge tag 'powerpc-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2020-12-24T22:02:00+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-12-24T22:02:00+00:00 9b3f7f1b841e91f0f0414525fa6edaaa2df33ccb Pull powerpc fixes from Michael Ellerman: - Four commits fixing various things in the new C VDSO code - One fix for a 32-bit VMAP stack bug - Two minor build fixes Thanks to Cédric Le Goater, Christophe Leroy, and Will Springer. * tag 'powerpc-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/32: Fix vmap stack - Properly set r1 before activating MMU on syscall too powerpc/vdso: Fix DOTSYM for 32-bit LE VDSO powerpc/vdso: Don't pass 64-bit ABI cflags to 32-bit VDSO powerpc/vdso: Block R_PPC_REL24 relocations powerpc/smp: Add __init to init_big_cores() powerpc/time: Force inlining of get_tb() powerpc/boot: Fix build of dts/fsl 
Pull powerpc fixes from Michael Ellerman:

 - Four commits fixing various things in the new C VDSO code

 - One fix for a 32-bit VMAP stack bug

 - Two minor build fixes

Thanks to Cédric Le Goater, Christophe Leroy, and Will Springer.

* tag 'powerpc-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32: Fix vmap stack - Properly set r1 before activating MMU on syscall too
  powerpc/vdso: Fix DOTSYM for 32-bit LE VDSO
  powerpc/vdso: Don't pass 64-bit ABI cflags to 32-bit VDSO
  powerpc/vdso: Block R_PPC_REL24 relocations
  powerpc/smp: Add __init to init_big_cores()
  powerpc/time: Force inlining of get_tb()
  powerpc/boot: Fix build of dts/fsl
Merge tag 'dma-mapping-5.11' of git://git.infradead.org/users/hch/dma-mapping 2020-12-22T21:19:43+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-12-22T21:19:43+00:00 347d81b68b8f7044c9ce3fefa130a736ca916176 Pull dma-mapping updates from Christoph Hellwig: - support for a partial IOMMU bypass (Alexey Kardashevskiy) - add a DMA API benchmark (Barry Song) - misc fixes (Tiezhu Yang, tangjianqiang) * tag 'dma-mapping-5.11' of git://git.infradead.org/users/hch/dma-mapping: selftests/dma: add test application for DMA_MAP_BENCHMARK dma-mapping: add benchmark support for streaming DMA APIs dma-contiguous: fix a typo error in a comment dma-pool: no need to check return value of debugfs_create functions powerpc/dma: Fallback to dma_ops when persistent memory present dma-mapping: Allow mixing bypass and mapped DMA operation 
Pull dma-mapping updates from Christoph Hellwig:

 - support for a partial IOMMU bypass (Alexey Kardashevskiy)

 - add a DMA API benchmark (Barry Song)

 - misc fixes (Tiezhu Yang, tangjianqiang)

* tag 'dma-mapping-5.11' of git://git.infradead.org/users/hch/dma-mapping:
  selftests/dma: add test application for DMA_MAP_BENCHMARK
  dma-mapping: add benchmark support for streaming DMA APIs
  dma-contiguous: fix a typo error in a comment
  dma-pool: no need to check return value of debugfs_create functions
  powerpc/dma: Fallback to dma_ops when persistent memory present
  dma-mapping: Allow mixing bypass and mapped DMA operation