linux.git/arch/powerpc/kernel/vmlinux.lds.S, branch v6.6 Linux kernel source tree powerpc/ftrace: Extend ftrace support for large kernels to ppc32 2023-08-21T14:09:05+00:00 Naveen N Rao naveen@kernel.org 2023-06-19T09:47:24+00:00 f3993a0330e2d11e42c095810c6c33084024df46 Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs") added ftrace support for ppc64 kernel images with a text section larger than 32MB. The approach itself isn't specific to ppc64, so extend the same to also work on ppc32. While at it, reduce the space reserved for the stub from 64 bytes to 32 bytes since the different stub variants are all less than 8 instructions. To reduce use of #ifdef, a stub implementation is provided for kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent errors on ppc32. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/9fa3258cbb9105cf8a0a8135214d44ffbc75fe84.1687166935.git.naveen@kernel.org 
Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
added ftrace support for ppc64 kernel images with a text section larger
than 32MB. The approach itself isn't specific to ppc64, so extend the
same to also work on ppc32.

While at it, reduce the space reserved for the stub from 64 bytes to 32
bytes since the different stub variants are all less than 8
instructions.

To reduce use of #ifdef, a stub implementation is provided for
kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent
errors on ppc32.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/9fa3258cbb9105cf8a0a8135214d44ffbc75fe84.1687166935.git.naveen@kernel.org
powerpc/64: vmlinux support building with PCREL addresing 2023-04-20T02:59:21+00:00 Nicholas Piggin npiggin@gmail.com 2023-04-08T02:17:51+00:00 7e3a68be42e10f5fa5890e97afc0afd992355bc3 PC-Relative or PCREL addressing is an extension to the ELF ABI which uses Power ISA v3.1 PC-relative instructions to calculate addresses, rather than the traditional TOC scheme. Add an option to build vmlinux using pcrel addressing. Modules continue to use TOC addressing. - TOC address helpers and r2 are poisoned with -1 when running vmlinux. r2 could be used for something useful once things are ironed out. - Assembly must call C functions with @notoc annotation, or the linker complains aobut a missing nop after the call. This is done with the CFUNC macro introduced earlier. - Boot: with the exception of prom_init, the execution branches to the kernel virtual address early in boot, before any addresses are generated, which ensures 34-bit pcrel addressing does not miss the high PAGE_OFFSET bits. TOC relative addressing has a similar requirement. prom_init does not go to the virtual address and its addresses should not carry over to the post-prom kernel. - Ftrace trampolines are converted from TOC addressing to pcrel addressing, including module ftrace trampolines that currently use the kernel TOC to find ftrace target functions. - BPF function prologue and function calling generation are converted from TOC to pcrel. - copypage_64.S has an interesting problem, prefixed instructions have alignment restrictions so the linker can add padding, which makes the assembler treat the difference between two local labels as non-constant even if alignment is arranged so padding is not required. This may need toolchain help to solve nicely, for now move the prefix instruction out of the alternate patch section to work around it. This reduces kernel text size by about 6%. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com 
PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
rather than the traditional TOC scheme.

Add an option to build vmlinux using pcrel addressing. Modules continue
to use TOC addressing.

- TOC address helpers and r2 are poisoned with -1 when running vmlinux.
  r2 could be used for something useful once things are ironed out.

- Assembly must call C functions with @notoc annotation, or the linker
  complains aobut a missing nop after the call. This is done with the
  CFUNC macro introduced earlier.

- Boot: with the exception of prom_init, the execution branches to the
  kernel virtual address early in boot, before any addresses are
  generated, which ensures 34-bit pcrel addressing does not miss the
  high PAGE_OFFSET bits. TOC relative addressing has a similar
  requirement. prom_init does not go to the virtual address and its
  addresses should not carry over to the post-prom kernel.

- Ftrace trampolines are converted from TOC addressing to pcrel
  addressing, including module ftrace trampolines that currently use the
  kernel TOC to find ftrace target functions.

- BPF function prologue and function calling generation are converted
  from TOC to pcrel.

- copypage_64.S has an interesting problem, prefixed instructions have
  alignment restrictions so the linker can add padding, which makes the
  assembler treat the difference between two local labels as
  non-constant even if alignment is arranged so padding is not required.
  This may need toolchain help to solve nicely, for now move the prefix
  instruction out of the alternate patch section to work around it.

This reduces kernel text size by about 6%.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com
powerpc/vmlinux.lds: Add .text.asan/tsan sections 2023-02-28T03:32:34+00:00 Michael Ellerman mpe@ellerman.id.au 2023-02-22T06:00:37+00:00 acd35dbab871d61021284ff06daccdc0ebb51e61 When KASAN/KCSAN are enabled clang generates .text.asan/tsan sections. Because they are not mentioned in the linker script warnings are generated, and when orphan handling is set to error that becomes a build error, eg: ld.lld: error: vmlinux.a(init/main.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor' ld.lld: error: vmlinux.a(init/version.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor' Fix it by adding the sections to our linker script, similar to the generic change made in 848378812e40 ("vmlinux.lds.h: Handle clang's module.{c,d}tor sections"). Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230222060037.2897169-1-mpe@ellerman.id.au 
When KASAN/KCSAN are enabled clang generates .text.asan/tsan sections.
Because they are not mentioned in the linker script warnings are
generated, and when orphan handling is set to error that becomes a build
error, eg:

  ld.lld: error: vmlinux.a(init/main.o):(.text.tsan.module_ctor) is
  being placed in '.text.tsan.module_ctor' ld.lld: error:
  vmlinux.a(init/version.o):(.text.tsan.module_ctor) is being placed in
  '.text.tsan.module_ctor'

Fix it by adding the sections to our linker script, similar to the
generic change made in 848378812e40 ("vmlinux.lds.h: Handle clang's
module.{c,d}tor sections").

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230222060037.2897169-1-mpe@ellerman.id.au
Merge tag 'v6.2-rc6' into sched/core, to pick up fixes 2023-01-31T14:01:20+00:00 Ingo Molnar mingo@kernel.org 2023-01-31T14:01:20+00:00 57a30218fa25c469ed507964bbf028b7a064309a Pick up fixes before merging another batch of cpuidle updates. Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Pick up fixes before merging another batch of cpuidle updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
objtool/idle: Validate __cpuidle code as noinstr 2023-01-13T10:48:15+00:00 Peter Zijlstra peterz@infradead.org 2023-01-12T19:43:31+00:00 2b5a0e425e6e319b1978db1e9564f6af4228a567 Idle code is very like entry code in that RCU isn't available. As such, add a little validation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20230112195540.373461409@infradead.org 
Idle code is very like entry code in that RCU isn't available. As
such, add a little validation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.373461409@infradead.org
powerpc/vmlinux.lds: Don't discard .comment 2023-01-05T13:25:12+00:00 Michael Ellerman mpe@ellerman.id.au 2023-01-05T11:42:59+00:00 be5f95c8779e19779dd81927c8574fec5aaba36c Although the powerpc linker script mentions .comment in the DISCARD section, that has never actually caused it to be discarded, because the earlier ELF_DETAILS macro (previously STABS_DEBUG) explicitly includes .comment. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro. With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier, causing .comment to actually be discarded. It's confusing to explicitly include and discard .comment, and even more so if the behaviour depends on the toolchain version. So don't discard .comment in order to maintain the existing behaviour in all cases. Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230105132349.384666-3-mpe@ellerman.id.au 
Although the powerpc linker script mentions .comment in the DISCARD
section, that has never actually caused it to be discarded, because the
earlier ELF_DETAILS macro (previously STABS_DEBUG) explicitly includes
.comment.

However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and
riscv") introduced an earlier use of DISCARD as part of the RO_DATA
macro. With binutils < 2.36 that causes the DISCARD directives later in
the script to be applied earlier, causing .comment to actually be
discarded.

It's confusing to explicitly include and discard .comment, and even more
so if the behaviour depends on the toolchain version. So don't discard
.comment in order to maintain the existing behaviour in all cases.

Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230105132349.384666-3-mpe@ellerman.id.au
powerpc/vmlinux.lds: Don't discard .rela* for relocatable builds 2023-01-05T13:25:01+00:00 Michael Ellerman mpe@ellerman.id.au 2023-01-05T11:28:36+00:00 07b050f9290ee012a407a0f64151db902a1520f5 Relocatable kernels must not discard relocations, they need to be processed at runtime. As such they are included for CONFIG_RELOCATABLE builds in the powerpc linker script (line 340). However they are also unconditionally discarded later in the script (line 414). Previously that worked because the earlier inclusion superseded the discard. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro (line 137). With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier, causing .rela* to actually be discarded at link time, leading to build warnings and a kernel that doesn't boot: ld: warning: discarding dynamic section .rela.init.rodata Fix it by conditionally discarding .rela* only when CONFIG_RELOCATABLE is disabled. Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230105132349.384666-2-mpe@ellerman.id.au 
Relocatable kernels must not discard relocations, they need to be
processed at runtime. As such they are included for CONFIG_RELOCATABLE
builds in the powerpc linker script (line 340).

However they are also unconditionally discarded later in the
script (line 414). Previously that worked because the earlier inclusion
superseded the discard.

However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and
riscv") introduced an earlier use of DISCARD as part of the RO_DATA
macro (line 137). With binutils < 2.36 that causes the DISCARD
directives later in the script to be applied earlier, causing .rela* to
actually be discarded at link time, leading to build warnings and a
kernel that doesn't boot:

  ld: warning: discarding dynamic section .rela.init.rodata

Fix it by conditionally discarding .rela* only when CONFIG_RELOCATABLE
is disabled.

Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Link: https://lore.kernel.org/r/20230105132349.384666-2-mpe@ellerman.id.au
powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT 2023-01-05T13:24:50+00:00 Michael Ellerman mpe@ellerman.id.au 2023-01-05T11:05:04+00:00 4b9880dbf3bdba3a7c56445137c3d0e30aaa0a40 The powerpc linker script explicitly includes .exit.text, because otherwise the link fails due to references from __bug_table and __ex_table. The code is freed (discarded) at runtime along with .init.text and data. That has worked in the past despite powerpc not defining RUNTIME_DISCARD_EXIT because DISCARDS appears late in the powerpc linker script (line 410), and the explicit inclusion of .exit.text earlier (line 280) supersedes the discard. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro (line 136). With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier [1], causing .exit.text to actually be discarded at link time, leading to build errors: '.exit.text' referenced in section '__bug_table' of crypto/algboss.o: defined in discarded section '.exit.text' of crypto/algboss.o '.exit.text' referenced in section '__ex_table' of drivers/nvdimm/core.o: defined in discarded section '.exit.text' of drivers/nvdimm/core.o Fix it by defining RUNTIME_DISCARD_EXIT, which causes the generic DISCARDS macro to not include .exit.text at all. 1: https://lore.kernel.org/lkml/87fscp2v7k.fsf@igel.home/ Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230105132349.384666-1-mpe@ellerman.id.au 
The powerpc linker script explicitly includes .exit.text, because
otherwise the link fails due to references from __bug_table and
__ex_table. The code is freed (discarded) at runtime along with
.init.text and data.

That has worked in the past despite powerpc not defining
RUNTIME_DISCARD_EXIT because DISCARDS appears late in the powerpc linker
script (line 410), and the explicit inclusion of .exit.text
earlier (line 280) supersedes the discard.

However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and
riscv") introduced an earlier use of DISCARD as part of the RO_DATA
macro (line 136). With binutils < 2.36 that causes the DISCARD
directives later in the script to be applied earlier [1], causing
.exit.text to actually be discarded at link time, leading to build
errors:

  '.exit.text' referenced in section '__bug_table' of crypto/algboss.o: defined in
  discarded section '.exit.text' of crypto/algboss.o
  '.exit.text' referenced in section '__ex_table' of drivers/nvdimm/core.o: defined in
  discarded section '.exit.text' of drivers/nvdimm/core.o

Fix it by defining RUNTIME_DISCARD_EXIT, which causes the generic
DISCARDS macro to not include .exit.text at all.

1: https://lore.kernel.org/lkml/87fscp2v7k.fsf@igel.home/

Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230105132349.384666-1-mpe@ellerman.id.au
powerpc: Fix writable sections being moved into the rodata region 2022-11-16T10:37:14+00:00 Nicholas Piggin npiggin@gmail.com 2022-11-16T04:39:53+00:00 eb761a1760bf30cf64e98ee8d914866e62ec9e8a .data.rel.ro* catches .data.rel.root_cpuacct, and the kernel crashes on a store in css_clear_dir. At least we know read-only data protection is working... Fixes: b6adc6d6d3272 ("powerpc/build: move .data.rel.ro, .sdata2 to read-only") Signed-off-by: Nicholas Piggin <npiggin@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/20221116043954.3307852-1-npiggin@gmail.com 
.data.rel.ro*  catches .data.rel.root_cpuacct, and the kernel crashes on
a store in css_clear_dir. At least we know read-only data protection is
working...

Fixes: b6adc6d6d3272 ("powerpc/build: move .data.rel.ro, .sdata2 to read-only")
Signed-off-by: Nicholas Piggin <npiggin@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/20221116043954.3307852-1-npiggin@gmail.com
powerpc: Drops STABS_DEBUG from linker scripts 2022-09-30T08:35:52+00:00 Michael Ellerman mpe@ellerman.id.au 2022-09-28T13:09:51+00:00 7673335e2a0b8e68a2a238773a34e287a089a8fe No toolchain we support should be generating stabs debug information anymore. Drop the sections entirely from our linker scripts. We removed all the manual stabs annotations in commit 12318163737c ("powerpc/32: Remove remaining .stabs annotations"). Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220928130951.1732983-1-mpe@ellerman.id.au 
No toolchain we support should be generating stabs debug information
anymore. Drop the sections entirely from our linker scripts.

We removed all the manual stabs annotations in commit
12318163737c ("powerpc/32: Remove remaining .stabs annotations").

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220928130951.1732983-1-mpe@ellerman.id.au