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  1. 06 Nov, 2019 3 commits
    • Mark Rutland's avatar
      arm64: module: rework special section handling · bd8b21d3
      Mark Rutland authored 
      When we load a module, we have to perform some special work for a couple
of named sections. To do this, we iterate over all of the module's
sections, and perform work for each section we recognize.

To make it easier to handle the unexpected absence of a section, and to
make the section-specific logic easer to read, let's factor the section
search into a helper. Similar is already done in the core module loader,
and other architectures (and ideally we'd unify these in future).

If we expect a module to have an ftrace trampoline section, but it
doesn't have one, we'll now reject loading the module. When
ARM64_MODULE_PLTS is selected, any correctly built module should have
one (and this is assumed by arm64's ftrace PLT code) and the absence of
such a section implies something has gone wrong at build time.

Subsequent patches will make use of the new helper.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: default avatarTorsten Duwe <duwe@suse.de>
Tested-by: default avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: default avatarTorsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
      bd8b21d3
    • Mark Rutland's avatar
      module/ftrace: handle patchable-function-entry · a1326b17
      Mark Rutland authored 
      When using patchable-function-entry, the compiler will record the
callsites into a section named "__patchable_function_entries" rather
than "__mcount_loc". Let's abstract this difference behind a new
FTRACE_CALLSITE_SECTION, so that architectures don't have to handle this
explicitly (e.g. with custom module linker scripts).

As parisc currently handles this explicitly, it is fixed up accordingly,
with its custom linker script removed. Since FTRACE_CALLSITE_SECTION is
only defined when DYNAMIC_FTRACE is selected, the parisc module loading
code is updated to only use the definition in that case. When
DYNAMIC_FTRACE is not selected, modules shouldn't have this section, so
this removes some redundant work in that case.

To make sure that this is keep up-to-date for modules and the main
kernel, a comment is added to vmlinux.lds.h, with the existing ifdeffery
simplified for legibility.

I built parisc generic-{32,64}bit_defconfig with DYNAMIC_FTRACE enabled,
and verified that the section made it into the .ko files for modules.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarHelge Deller <deller@gmx.de>
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: default avatarTorsten Duwe <duwe@suse.de>
Tested-by: default avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: default avatarSven Schnelle <svens@stackframe.org>
Tested-by: default avatarTorsten Duwe <duwe@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: linux-parisc@vger.kernel.org
      a1326b17
    • Mark Rutland's avatar
      ftrace: add ftrace_init_nop() · fbf6c73c
      Mark Rutland authored 
      Architectures may need to perform special initialization of ftrace
callsites, and today they do so by special-casing ftrace_make_nop() when
the expected branch address is MCOUNT_ADDR. In some cases (e.g. for
patchable-function-entry), we don't have an mcount-like symbol and don't
want a synthetic MCOUNT_ADDR, but we may need to perform some
initialization of callsites.

To make it possible to separate initialization from runtime
modification, and to handle cases without an mcount-like symbol, this
patch adds an optional ftrace_init_nop() function that architectures can
implement, which does not pass a branch address.

Where an architecture does not provide ftrace_init_nop(), we will fall
back to the existing behaviour of calling ftrace_make_nop() with
MCOUNT_ADDR.

At the same time, ftrace_code_disable() is renamed to
ftrace_nop_initialize() to make it clearer that it is intended to
intialize a callsite into a disabled state, and is not for disabling a
callsite that has been runtime enabled. The kerneldoc description of rec
arguments is updated to cover non-mcount callsites.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: default avatarTorsten Duwe <duwe@suse.de>
Tested-by: default avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: default avatarSven Schnelle <svens@stackframe.org>
Tested-by: default avatarTorsten Duwe <duwe@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
      fbf6c73c
  3. 13 Oct, 2019 16 commits
  5. 12 Oct, 2019 21 commits
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