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Subject[RFC PATCH tip/master V2 0/8] kprobes/x86: Make kprobes instruction buffers read-only

This is the 2nd version of the series, which has been updated
only 8/8, built and tested correctly. (Sorry, in previous version
I missed to build and tested different kernel.)

This series tries to make kprobes instruction buffers read-only
pages. Since those buffers are used for trampoline code, those
are a part of "text area" and it should be marked as ro for
avoiding unexpected modification. And this actually fix a warning
rodata sanity check reported by lkp-robot.

This change requires changing the kprobe-booster at first
because it can modify the instruction buffer to add a jump while
resuming from single-stepping. Of course after we make the buffer
readonly, we may not be able to modify it while probing.

So, at first this series checks the current bootable instructions
and fixes a missed instruction (call far), modifies can_boost to
use x86 instruction decoder, and inserts "booster" jump while
preparing instruction buffer instead of resuming from single-stepping.
At last, it makes the buffers for kprobes and optprobe readonly.

This series also has some cleanup patches related to above

Changes from V1:
- [8/8]: Fix build errors.


Masami Hiramatsu (8):
kprobes/x86: Fix not to boost call far instruction
kprobes/x86: Fix the description of __copy_instruction()
kprobes/x86: Use instruction decoder for booster
kprobes/x86: Do not modify singlestep buffer while resuming
kprobes/x86: Make boostable flag boolean
kprobes/x86: Set kprobes pages readonly
kprobes/x86: Use probe_kernel_read instead of memcpy
kprobes/x86: Consolidate insn decoder users for copying code

arch/x86/include/asm/kprobes.h | 7 +-
arch/x86/kernel/kprobes/common.h | 4 +
arch/x86/kernel/kprobes/core.c | 148 +++++++++++++++++++-------------------
arch/x86/kernel/kprobes/ftrace.c | 2 -
arch/x86/kernel/kprobes/opt.c | 13 +++
5 files changed, 89 insertions(+), 85 deletions(-)

Masami Hiramatsu (Linaro) <>

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