module/retpoline: Warn about missing retpoline in module

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There's a risk that a kernel which has full retpoline mitigations becomes
vulnerable when a module gets loaded that hasn't been compiled with the
right compiler or the right option.

To enable detection of that mismatch at module load time, add a module info
string "retpoline" at build time when the module was compiled with
retpoline support. This only covers compiled C source, but assembler source
or prebuilt object files are not checked.

If a retpoline enabled kernel detects a non retpoline protected module at
load time, print a warning and report it in the sysfs vulnerability file.

[ tglx: Massaged changelog ]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: gregkh@linuxfoundation.org
Cc: torvalds@linux-foundation.org
Cc: jeyu@kernel.org
Cc: arjan@linux.intel.com
Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org

...

This commit is contained in:

Andi Kleen 2018-01-25 15:50:28 -08:00 • committed by Thomas Gleixner

parent c940a3fb1e

commit caf7501a1b

4 changed files with 45 additions and 1 deletions

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17

arch/x86/kernel/cpu/bugs.c

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9

include/linux/module.h

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11

kernel/module.c

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9

scripts/mod/modpost.c

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