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  1. Sep 29, 2016
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  9. Sep 19, 2016
    • Michael Ellerman's avatar
      powerpc: Ensure .mem(init|exit).text are within _stext/_etext · 7de3b27b
      Michael Ellerman authored 
      

In our linker script we open code the list of text sections, because we
need to include the __ftr_alt sections, which are arch-specific.

This means we can't use TEXT_TEXT as defined in vmlinux.lds.h, and so we
don't have the MEM_KEEP() logic for memory hotplug sections.

If we build the kernel with the gold linker, and with CONFIG_MEMORY_HOTPLUG=y,
we see that functions marked __meminit can end up outside of the
_stext/_etext range, and also outside of _sinittext/_einittext, eg:

    c000000000000000 T _stext
    c0000000009e0000 A _etext
    c0000000009e3f18 T hash__vmemmap_create_mapping
    c000000000ca0000 T _sinittext
    c000000000d00844 T _einittext

This causes them to not be recognised as text by is_kernel_text(), and
prevents them being patched by jump_label (and presumably ftrace/kprobes
etc.).

Fix it by adding MEM_KEEP() directives, mirroring what TEXT_TEXT does.

This isn't a problem when CONFIG_MEMORY_HOTPLUG=n, because we use the
standard INIT_TEXT_SECTION() and EXIT_TEXT macros from vmlinux.lds.h.

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Tested-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      7de3b27b
    • Michael Ellerman's avatar
      powerpc: Don't change the section in _GLOBAL() · bea2dccc
      Michael Ellerman authored 
      

Currently the _GLOBAL() macro unilaterally sets the assembler section to
".text" at the start of the macro. This is rude as the caller may be
using a different section.

So let the caller decide which section to emit the code into. On big
endian we do need to switch to the ".opd" section to emit the OPD, but
do that with pushsection/popsection, thereby leaving the original
section intact.

I verified that the order of all entries in System.map is unchanged
after this patch. The actual addresses shift around slightly so you
can't just diff the System.map.

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      bea2dccc
    • Nicholas Piggin's avatar
      powerpc/kernel: Use kprobe blacklist for asm functions · 6f698df1
      Nicholas Piggin authored 
      

Rather than forcing the whole function into the ".kprobes.text" section,
just add the symbol's address to the kprobe blacklist.

This also lets us drop the three versions of the_KPROBE macro, in
exchange for just one version of _ASM_NOKPROBE_SYMBOL - which is a good
cleanup.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      6f698df1
    • Nicholas Piggin's avatar
      powerpc: Use kprobe blacklist for exception handlers · 03465f89
      Nicholas Piggin authored 
      

Currently we mark the C implementations of some exception handlers as
__kprobes. This has the effect of putting them in the ".kprobes.text"
section, which separates them from the rest of the text.

Instead we can use the blacklist macros to add the symbols to a
blacklist which kprobes will check. This allows the linker to move
exception handler functions close to callers and avoids trampolines in
larger kernels.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
[mpe: Reword change log a bit]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      03465f89
  11. Sep 13, 2016
    • Simon Guo's avatar
      powerpc: Set used_(vsr|vr|spe) in sigreturn path when MSR bits are active · e1c0d66f
      Simon Guo authored 
      

Normally, when MSR[VSX/VR/SPE] bits == 1, the used_vsr/used_vr/used_spe
bit have already been set. However when loading a signal frame from user
space we need to explicitly set used_vsr/used_vr/used_spe to make them
consistent with the MSR bits from the signal frame.

For example, CRIU application, who utilizes sigreturn to restore
checkpointed process, will lead to the case where MSR[VSX] bit is active
in signal frame, but used_vsr bit is not set in the kernel. (the same
applies to VR/SPE).

This patch fixes this by always setting used_* bit when MSR related bits
are active in signal frame and we are doing sigreturn.

Based on a proposal by Benh.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarSimon Guo <wei.guo.simon@gmail.com>
[mpe: Massage change log]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      e1c0d66f