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[V2,0/3] riscv: ftrace: Fixup ftrace detour code

Message ID 20220921034910.3142465-1-guoren@kernel.org (mailing list archive)
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Series riscv: ftrace: Fixup ftrace detour code | expand

Message

Guo Ren Sept. 21, 2022, 3:49 a.m. UTC 
From: Guo Ren <guoren@linux.alibaba.com>

The previous ftrace detour implementation fc76b8b8011 ("riscv: Using
PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") contain three problems. The
most horrible bug is preemption panic which found by Andy [1]. Let's
disable preemption for ftrace first, and Andy could continue the
ftrace preemption work.

[1]: https://lpc.events/event/16/contributions/1171/

V2:
 - Add Signed-off for preemption fixup.

V1:
https://lore.kernel.org/linux-riscv/20220916103817.9490-1-guoren@kernel.org/

Andy Chiu (1):
  riscv: ftrace: Fixup panic by disabling preemption

Guo Ren (2):
  riscv: ftrace: Remove wasted nops for !RISCV_ISA_C
  riscv: ftrace: Reduce the detour code size to half

 arch/riscv/Kconfig              |  2 +-
 arch/riscv/Makefile             |  6 ++-
 arch/riscv/include/asm/ftrace.h | 46 ++++++++++++++++++-----
 arch/riscv/kernel/ftrace.c      | 65 ++++++++++-----------------------
 arch/riscv/kernel/mcount-dyn.S  | 43 +++++++++-------------
 5 files changed, 78 insertions(+), 84 deletions(-)