linux.git/arch/powerpc/kernel/vmlinux.lds.S, branch v5.10 Linux kernel source tree powerpc/64s: flush L1D after user accesses 2020-11-19T12:47:18+00:00 Nicholas Piggin npiggin@gmail.com 2020-11-17T05:59:13+00:00 9a32a7e78bd0cd9a9b6332cbdc345ee5ffd0c5de IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache after user accesses. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
IBM Power9 processors can speculatively operate on data in the L1 cache
before it has been completely validated, via a way-prediction mechanism. It
is not possible for an attacker to determine the contents of impermissible
memory using this method, since these systems implement a combination of
hardware and software security measures to prevent scenarios where
protected data could be leaked.

However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that
the attacker controls. This can be used for example to speculatively bypass
"kernel user access prevention" techniques, as discovered by Anthony
Steinhauser of Google's Safeside Project. This is not an attack by itself,
but there is a possibility it could be used in conjunction with
side-channels or other weaknesses in the privileged code to construct an
attack.

This issue can be mitigated by flushing the L1 cache between privilege
boundaries of concern. This patch flushes the L1 cache after user accesses.

This is part of the fix for CVE-2020-4788.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/64s: flush L1D on kernel entry 2020-11-19T12:47:15+00:00 Nicholas Piggin npiggin@gmail.com 2020-11-17T05:59:12+00:00 f79643787e0a0762d2409b7b8334e83f22d85695 IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache on kernel entry. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
IBM Power9 processors can speculatively operate on data in the L1 cache
before it has been completely validated, via a way-prediction mechanism. It
is not possible for an attacker to determine the contents of impermissible
memory using this method, since these systems implement a combination of
hardware and software security measures to prevent scenarios where
protected data could be leaked.

However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that
the attacker controls. This can be used for example to speculatively bypass
"kernel user access prevention" techniques, as discovered by Anthony
Steinhauser of Google's Safeside Project. This is not an attack by itself,
but there is a possibility it could be used in conjunction with
side-channels or other weaknesses in the privileged code to construct an
attack.

This issue can be mitigated by flushing the L1 cache between privilege
boundaries of concern. This patch flushes the L1 cache on kernel entry.

This is part of the fix for CVE-2020-4788.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG 2020-09-01T07:50:35+00:00 Kees Cook keescook@chromium.org 2020-08-21T19:42:45+00:00 c604abc3f6e3030f3a3022b184ed7d3780c34d30 The .comment section doesn't belong in STABS_DEBUG. Split it out into a new macro named ELF_DETAILS. This will gain other non-debug sections that need to be accounted for when linking with --orphan-handling=warn. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-arch@vger.kernel.org Link: https://lore.kernel.org/r/20200821194310.3089815-5-keescook@chromium.org 
The .comment section doesn't belong in STABS_DEBUG. Split it out into a
new macro named ELF_DETAILS. This will gain other non-debug sections
that need to be accounted for when linking with --orphan-handling=warn.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-arch@vger.kernel.org
Link: https://lore.kernel.org/r/20200821194310.3089815-5-keescook@chromium.org
Merge tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2020-06-05T19:39:30+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-06-05T19:39:30+00:00 7ae77150d94d3b535c7b85e6b3647113095e79bf Pull powerpc updates from Michael Ellerman: - Support for userspace to send requests directly to the on-chip GZIP accelerator on Power9. - Rework of our lockless page table walking (__find_linux_pte()) to make it safe against parallel page table manipulations without relying on an IPI for serialisation. - A series of fixes & enhancements to make our machine check handling more robust. - Lots of plumbing to add support for "prefixed" (64-bit) instructions on Power10. - Support for using huge pages for the linear mapping on 8xx (32-bit). - Remove obsolete Xilinx PPC405/PPC440 support, and an associated sound driver. - Removal of some obsolete 40x platforms and associated cruft. - Initial support for booting on Power10. - Lots of other small features, cleanups & fixes. Thanks to: Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan, Andrey Abramov, Aneesh Kumar K.V, Balamuruhan S, Bharata B Rao, Bulent Abali, Cédric Le Goater, Chen Zhou, Christian Zigotzky, Christophe JAILLET, Christophe Leroy, Dmitry Torokhov, Emmanuel Nicolet, Erhard F., Gautham R. Shenoy, Geoff Levand, George Spelvin, Greg Kurz, Gustavo A. R. Silva, Gustavo Walbon, Haren Myneni, Hari Bathini, Joel Stanley, Jordan Niethe, Kajol Jain, Kees Cook, Leonardo Bras, Madhavan Srinivasan., Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Michal Simek, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Paul Mackerras, Pingfan Liu, Qian Cai, Ram Pai, Raphael Moreira Zinsly, Ravi Bangoria, Sam Bobroff, Sandipan Das, Segher Boessenkool, Stephen Rothwell, Sukadev Bhattiprolu, Tyrel Datwyler, Wolfram Sang, Xiongfeng Wang. * tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (299 commits) powerpc/pseries: Make vio and ibmebus initcalls pseries specific cxl: Remove dead Kconfig options powerpc: Add POWER10 architected mode powerpc/dt_cpu_ftrs: Add MMA feature powerpc/dt_cpu_ftrs: Enable Prefixed Instructions powerpc/dt_cpu_ftrs: Advertise support for ISA v3.1 if selected powerpc: Add support for ISA v3.1 powerpc: Add new HWCAP bits powerpc/64s: Don't set FSCR bits in INIT_THREAD powerpc/64s: Save FSCR to init_task.thread.fscr after feature init powerpc/64s: Don't let DT CPU features set FSCR_DSCR powerpc/64s: Don't init FSCR_DSCR in __init_FSCR() powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUG powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations powerpc/module_64: Consolidate ftrace code powerpc/32: Disable KASAN with pages bigger than 16k powerpc/uaccess: Don't set KUEP by default on book3s/32 powerpc/uaccess: Don't set KUAP by default on book3s/32 powerpc/8xx: Reduce time spent in allow_user_access() and friends ... 
Pull powerpc updates from Michael Ellerman:

 - Support for userspace to send requests directly to the on-chip GZIP
   accelerator on Power9.

 - Rework of our lockless page table walking (__find_linux_pte()) to
   make it safe against parallel page table manipulations without
   relying on an IPI for serialisation.

 - A series of fixes & enhancements to make our machine check handling
   more robust.

 - Lots of plumbing to add support for "prefixed" (64-bit) instructions
   on Power10.

 - Support for using huge pages for the linear mapping on 8xx (32-bit).

 - Remove obsolete Xilinx PPC405/PPC440 support, and an associated sound
   driver.

 - Removal of some obsolete 40x platforms and associated cruft.

 - Initial support for booting on Power10.

 - Lots of other small features, cleanups & fixes.

Thanks to: Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan,
Andrey Abramov, Aneesh Kumar K.V, Balamuruhan S, Bharata B Rao, Bulent
Abali, Cédric Le Goater, Chen Zhou, Christian Zigotzky, Christophe
JAILLET, Christophe Leroy, Dmitry Torokhov, Emmanuel Nicolet, Erhard F.,
Gautham R. Shenoy, Geoff Levand, George Spelvin, Greg Kurz, Gustavo A.
R. Silva, Gustavo Walbon, Haren Myneni, Hari Bathini, Joel Stanley,
Jordan Niethe, Kajol Jain, Kees Cook, Leonardo Bras, Madhavan
Srinivasan., Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Michal
Simek, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin,
Oliver O'Halloran, Paul Mackerras, Pingfan Liu, Qian Cai, Ram Pai,
Raphael Moreira Zinsly, Ravi Bangoria, Sam Bobroff, Sandipan Das, Segher
Boessenkool, Stephen Rothwell, Sukadev Bhattiprolu, Tyrel Datwyler,
Wolfram Sang, Xiongfeng Wang.

* tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (299 commits)
  powerpc/pseries: Make vio and ibmebus initcalls pseries specific
  cxl: Remove dead Kconfig options
  powerpc: Add POWER10 architected mode
  powerpc/dt_cpu_ftrs: Add MMA feature
  powerpc/dt_cpu_ftrs: Enable Prefixed Instructions
  powerpc/dt_cpu_ftrs: Advertise support for ISA v3.1 if selected
  powerpc: Add support for ISA v3.1
  powerpc: Add new HWCAP bits
  powerpc/64s: Don't set FSCR bits in INIT_THREAD
  powerpc/64s: Save FSCR to init_task.thread.fscr after feature init
  powerpc/64s: Don't let DT CPU features set FSCR_DSCR
  powerpc/64s: Don't init FSCR_DSCR in __init_FSCR()
  powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUG
  powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel
  powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations
  powerpc/module_64: Consolidate ftrace code
  powerpc/32: Disable KASAN with pages bigger than 16k
  powerpc/uaccess: Don't set KUEP by default on book3s/32
  powerpc/uaccess: Don't set KUAP by default on book3s/32
  powerpc/8xx: Reduce time spent in allow_user_access() and friends
  ...
powerpc/mm: Don't be too strict with _etext alignment on PPC32 2020-05-26T12:22:22+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2020-05-19T05:49:19+00:00 a0591b60eef965f7f5255ad4696bbba9af4b43d0 Similar to PPC64, accept to map RO data as ROX as a trade off between between security and memory usage. Having RO data executable is not a high risk as RO data can't be modified to forge an exploit. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/8c4a0d89d944eed984dd941e509614031a5ace2b.1589866984.git.christophe.leroy@csgroup.eu 
Similar to PPC64, accept to map RO data as ROX as a trade off between
between security and memory usage.

Having RO data executable is not a high risk as RO data can't be
modified to forge an exploit.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8c4a0d89d944eed984dd941e509614031a5ace2b.1589866984.git.christophe.leroy@csgroup.eu
vmlinux.lds.h: Create section for protection against instrumentation 2020-05-19T13:47:20+00:00 Thomas Gleixner tglx@linutronix.de 2020-03-09T21:47:17+00:00 6553896666433e7efec589838b400a2a652b3ffa Some code pathes, especially the low level entry code, must be protected against instrumentation for various reasons: - Low level entry code can be a fragile beast, especially on x86. - With NO_HZ_FULL RCU state needs to be established before using it. Having a dedicated section for such code allows to validate with tooling that no unsafe functions are invoked. Add the .noinstr.text section and the noinstr attribute to mark functions. noinstr implies notrace. Kprobes will gain a section check later. Provide also a set of markers: instrumentation_begin()/end() These are used to mark code inside a noinstr function which calls into regular instrumentable text section as safe. The instrumentation markers are only active when CONFIG_DEBUG_ENTRY is enabled as the end marker emits a NOP to prevent the compiler from merging the annotation points. This means the objtool verification requires a kernel compiled with this option. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134100.075416272@linutronix.de 
Some code pathes, especially the low level entry code, must be protected
against instrumentation for various reasons:

 - Low level entry code can be a fragile beast, especially on x86.

 - With NO_HZ_FULL RCU state needs to be established before using it.

Having a dedicated section for such code allows to validate with tooling
that no unsafe functions are invoked.

Add the .noinstr.text section and the noinstr attribute to mark
functions. noinstr implies notrace. Kprobes will gain a section check
later.

Provide also a set of markers: instrumentation_begin()/end()

These are used to mark code inside a noinstr function which calls
into regular instrumentable text section as safe.

The instrumentation markers are only active when CONFIG_DEBUG_ENTRY is
enabled as the end marker emits a NOP to prevent the compiler from merging
the annotation points. This means the objtool verification requires a
kernel compiled with this option.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134100.075416272@linutronix.de
Merge tag 'powerpc-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2020-04-05T18:12:59+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-04-05T18:12:59+00:00 d38c07afc356ddebaa3ed8ecb3f553340e05c969 Pull powerpc updates from Michael Ellerman: "Slightly late as I had to rebase mid-week to insert a bug fix: - A large series from Nick for 64-bit to further rework our exception vectors, and rewrite portions of the syscall entry/exit and interrupt return in C. The result is much easier to follow code that is also faster in general. - Cleanup of our ptrace code to split various parts out that had become badly intertwined with #ifdefs over the years. - Changes to our NUMA setup under the PowerVM hypervisor which should hopefully avoid non-sensical topologies which can lead to warnings from the workqueue code and other problems. - MAINTAINERS updates to remove some of our old orphan entries and update the status of others. - Quite a few other small changes and fixes all over the map. Thanks to: Abdul Haleem, afzal mohammed, Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V, Balamuruhan S, Cédric Le Goater, Chen Zhou, Christophe JAILLET, Christophe Leroy, Christoph Hellwig, Clement Courbet, Daniel Axtens, David Gibson, Douglas Miller, Fabiano Rosas, Fangrui Song, Ganesh Goudar, Gautham R. Shenoy, Greg Kroah-Hartman, Greg Kurz, Gustavo Luiz Duarte, Hari Bathini, Ilie Halip, Jan Kara, Joe Lawrence, Joe Perches, Kajol Jain, Larry Finger, Laurentiu Tudor, Leonardo Bras, Libor Pechacek, Madhavan Srinivasan, Mahesh Salgaonkar, Masahiro Yamada, Masami Hiramatsu, Mauricio Faria de Oliveira, Michael Neuling, Michal Suchanek, Mike Rapoport, Nageswara R Sastry, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Nick Desaulniers, Oliver O'Halloran, Po-Hsu Lin, Pratik Rajesh Sampat, Rasmus Villemoes, Ravi Bangoria, Roman Bolshakov, Sam Bobroff, Sandipan Das, Santosh S, Sedat Dilek, Segher Boessenkool, Shilpasri G Bhat, Sourabh Jain, Srikar Dronamraju, Stephen Rothwell, Tyrel Datwyler, Vaibhav Jain, YueHaibing" * tag 'powerpc-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (158 commits) powerpc: Make setjmp/longjmp signature standard powerpc/cputable: Remove unnecessary copy of cpu_spec->oprofile_type powerpc: Suppress .eh_frame generation powerpc: Drop -fno-dwarf2-cfi-asm powerpc/32: drop unused ISA_DMA_THRESHOLD powerpc/powernv: Add documentation for the opal sensor_groups sysfs interfaces selftests/powerpc: Fix try-run when source tree is not writable powerpc/vmlinux.lds: Explicitly retain .gnu.hash powerpc/ptrace: move ptrace_triggered() into hw_breakpoint.c powerpc/ptrace: create ppc_gethwdinfo() powerpc/ptrace: create ptrace_get_debugreg() powerpc/ptrace: split out ADV_DEBUG_REGS related functions. powerpc/ptrace: move register viewing functions out of ptrace.c powerpc/ptrace: split out TRANSACTIONAL_MEM related functions. powerpc/ptrace: split out SPE related functions. powerpc/ptrace: split out ALTIVEC related functions. powerpc/ptrace: split out VSX related functions. powerpc/ptrace: drop PARAMETER_SAVE_AREA_OFFSET powerpc/ptrace: drop unnecessary #ifdefs CONFIG_PPC64 powerpc/ptrace: remove unused header includes ... 
Pull powerpc updates from Michael Ellerman:
 "Slightly late as I had to rebase mid-week to insert a bug fix:

   - A large series from Nick for 64-bit to further rework our exception
     vectors, and rewrite portions of the syscall entry/exit and
     interrupt return in C. The result is much easier to follow code
     that is also faster in general.

   - Cleanup of our ptrace code to split various parts out that had
     become badly intertwined with #ifdefs over the years.

   - Changes to our NUMA setup under the PowerVM hypervisor which should
     hopefully avoid non-sensical topologies which can lead to warnings
     from the workqueue code and other problems.

   - MAINTAINERS updates to remove some of our old orphan entries and
     update the status of others.

   - Quite a few other small changes and fixes all over the map.

  Thanks to: Abdul Haleem, afzal mohammed, Alexey Kardashevskiy, Andrew
  Donnellan, Aneesh Kumar K.V, Balamuruhan S, Cédric Le Goater, Chen
  Zhou, Christophe JAILLET, Christophe Leroy, Christoph Hellwig, Clement
  Courbet, Daniel Axtens, David Gibson, Douglas Miller, Fabiano Rosas,
  Fangrui Song, Ganesh Goudar, Gautham R. Shenoy, Greg Kroah-Hartman,
  Greg Kurz, Gustavo Luiz Duarte, Hari Bathini, Ilie Halip, Jan Kara,
  Joe Lawrence, Joe Perches, Kajol Jain, Larry Finger, Laurentiu Tudor,
  Leonardo Bras, Libor Pechacek, Madhavan Srinivasan, Mahesh Salgaonkar,
  Masahiro Yamada, Masami Hiramatsu, Mauricio Faria de Oliveira, Michael
  Neuling, Michal Suchanek, Mike Rapoport, Nageswara R Sastry, Nathan
  Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Nick
  Desaulniers, Oliver O'Halloran, Po-Hsu Lin, Pratik Rajesh Sampat,
  Rasmus Villemoes, Ravi Bangoria, Roman Bolshakov, Sam Bobroff,
  Sandipan Das, Santosh S, Sedat Dilek, Segher Boessenkool, Shilpasri G
  Bhat, Sourabh Jain, Srikar Dronamraju, Stephen Rothwell, Tyrel
  Datwyler, Vaibhav Jain, YueHaibing"

* tag 'powerpc-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (158 commits)
  powerpc: Make setjmp/longjmp signature standard
  powerpc/cputable: Remove unnecessary copy of cpu_spec->oprofile_type
  powerpc: Suppress .eh_frame generation
  powerpc: Drop -fno-dwarf2-cfi-asm
  powerpc/32: drop unused ISA_DMA_THRESHOLD
  powerpc/powernv: Add documentation for the opal sensor_groups sysfs interfaces
  selftests/powerpc: Fix try-run when source tree is not writable
  powerpc/vmlinux.lds: Explicitly retain .gnu.hash
  powerpc/ptrace: move ptrace_triggered() into hw_breakpoint.c
  powerpc/ptrace: create ppc_gethwdinfo()
  powerpc/ptrace: create ptrace_get_debugreg()
  powerpc/ptrace: split out ADV_DEBUG_REGS related functions.
  powerpc/ptrace: move register viewing functions out of ptrace.c
  powerpc/ptrace: split out TRANSACTIONAL_MEM related functions.
  powerpc/ptrace: split out SPE related functions.
  powerpc/ptrace: split out ALTIVEC related functions.
  powerpc/ptrace: split out VSX related functions.
  powerpc/ptrace: drop PARAMETER_SAVE_AREA_OFFSET
  powerpc/ptrace: drop unnecessary #ifdefs CONFIG_PPC64
  powerpc/ptrace: remove unused header includes
  ...
powerpc/vmlinux.lds: Explicitly retain .gnu.hash 2020-04-01T03:30:50+00:00 Michael Ellerman mpe@ellerman.id.au 2020-02-27T04:59:32+00:00 ead983604c5a390f1e3ce085945b60e82f08dbbe Relocatable kernel builds produce a warning about .gnu.hash being an orphan section: ld: warning: orphan section `.gnu.hash' from `linker stubs' being placed in section `.gnu.hash' If we try to discard it the build fails: ld -EL -m elf64lppc -pie --orphan-handling=warn --build-id -o .tmp_vmlinux1 -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive arch/powerpc/kernel/head_64.o arch/powerpc/kernel/entry_64.o ... sound/built-in.a net/built-in.a virt/built-in.a --no-whole-archive --start-group lib/lib.a --end-group ld: could not find section .gnu.hash So add an entry to explicitly retain it, as we do for .hash. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200227045933.22967-1-mpe@ellerman.id.au 
Relocatable kernel builds produce a warning about .gnu.hash being an
orphan section:

  ld: warning: orphan section `.gnu.hash' from `linker stubs' being placed in section `.gnu.hash'

If we try to discard it the build fails:

  ld -EL -m elf64lppc -pie --orphan-handling=warn --build-id -o
    .tmp_vmlinux1 -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive
    arch/powerpc/kernel/head_64.o arch/powerpc/kernel/entry_64.o
    ...
    sound/built-in.a net/built-in.a virt/built-in.a --no-whole-archive
    --start-group lib/lib.a --end-group
  ld: could not find section .gnu.hash

So add an entry to explicitly retain it, as we do for .hash.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200227045933.22967-1-mpe@ellerman.id.au
bpf: Support llvm-objcopy for vmlinux BTF 2020-03-19T11:32:38+00:00 Fangrui Song maskray@google.com 2020-03-18T22:27:46+00:00 90ceddcb495008ac8ba7a3dce297841efcd7d584 Simplify gen_btf logic to make it work with llvm-objcopy. The existing 'file format' and 'architecture' parsing logic is brittle and does not work with llvm-objcopy/llvm-objdump. 'file format' output of llvm-objdump>=11 will match GNU objdump, but 'architecture' (bfdarch) may not. .BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag because it is part of vmlinux image used for introspection. C code can reference the section via linker script defined __start_BTF and __stop_BTF. This fixes a small problem that previous .BTF had the SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data). Additionally, `objcopy -I binary` synthesized symbols _binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not used elsewhere) are replaced with more commonplace __start_BTF and __stop_BTF. Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns "empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?" We use a dd command to change the e_type field in the ELF header from ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o. Accepting ET_EXEC as an input file is an extremely rare GNU ld feature that lld does not intend to support, because this is error-prone. The output section description .BTF in include/asm-generic/vmlinux.lds.h avoids potential subtle orphan section placement issues and suppresses --orphan-handling=warn warnings. Fixes: df786c9b9476 ("bpf: Force .BTF section start to zero when dumping from vmlinux") Fixes: cb0cc635c7a9 ("powerpc: Include .BTF section") Reported-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Fangrui Song <maskray@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Stanislav Fomichev <sdf@google.com> Tested-by: Andrii Nakryiko <andriin@fb.com> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://github.com/ClangBuiltLinux/linux/issues/871 Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com 
Simplify gen_btf logic to make it work with llvm-objcopy. The existing
'file format' and 'architecture' parsing logic is brittle and does not
work with llvm-objcopy/llvm-objdump.

'file format' output of llvm-objdump>=11 will match GNU objdump, but
'architecture' (bfdarch) may not.

.BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag
because it is part of vmlinux image used for introspection. C code
can reference the section via linker script defined __start_BTF and
__stop_BTF. This fixes a small problem that previous .BTF had the
SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data).

Additionally, `objcopy -I binary` synthesized symbols
_binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not
used elsewhere) are replaced with more commonplace __start_BTF and
__stop_BTF.

Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns
"empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?"

We use a dd command to change the e_type field in the ELF header from
ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o.  Accepting
ET_EXEC as an input file is an extremely rare GNU ld feature that lld
does not intend to support, because this is error-prone.

The output section description .BTF in include/asm-generic/vmlinux.lds.h
avoids potential subtle orphan section placement issues and suppresses
--orphan-handling=warn warnings.

Fixes: df786c9b9476 ("bpf: Force .BTF section start to zero when dumping from vmlinux")
Fixes: cb0cc635c7a9 ("powerpc: Include .BTF section")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Stanislav Fomichev <sdf@google.com>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://github.com/ClangBuiltLinux/linux/issues/871
Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com
powerpc: Include .BTF section 2020-02-24T11:04:07+00:00 Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com 2020-02-20T11:31:32+00:00 cb0cc635c7a9fa8a3a0f75d4d896721819c63add Selecting CONFIG_DEBUG_INFO_BTF results in the below warning from ld: ld: warning: orphan section `.BTF' from `.btf.vmlinux.bin.o' being placed in section `.BTF' Include .BTF section in vmlinux explicitly to fix the same. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200220113132.857132-1-naveen.n.rao@linux.vnet.ibm.com 
Selecting CONFIG_DEBUG_INFO_BTF results in the below warning from ld:
  ld: warning: orphan section `.BTF' from `.btf.vmlinux.bin.o' being placed in section `.BTF'

Include .BTF section in vmlinux explicitly to fix the same.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200220113132.857132-1-naveen.n.rao@linux.vnet.ibm.com