linux-kernel - Re: [PATCH -next V7 0/7] riscv: Optimize function trace

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Date:   Sat, 18 Feb 2023 21:42:30 +0000
From:   patchwork-bot+linux-riscv@...nel.org
To:     Guo Ren <guoren@...nel.org>
Cc:     linux-riscv@...ts.infradead.org, anup@...infault.org,
        paul.walmsley@...ive.com, palmer@...belt.com,
        conor.dooley@...rochip.com, heiko@...ech.de, rostedt@...dmis.org,
        mhiramat@...nel.org, jolsa@...hat.com, bp@...e.de,
        jpoimboe@...nel.org, suagrfillet@...il.com, andy.chiu@...ive.com,
        e.shatokhin@...ro.com, linux-kernel@...r.kernel.org,
        guoren@...ux.alibaba.com
Subject: Re: [PATCH -next V7 0/7] riscv: Optimize function trace

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@...osinc.com>:

On Thu, 12 Jan 2023 04:05:56 -0500 you wrote:
> From: Guo Ren <guoren@...ux.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.
>  - The "-fpatchable-function-entry= CFLAG" wasted code size
>    !RISCV_ISA_C.
>  - The ftrace detour implementation wasted code size.
>  - When livepatching, the trampoline (ftrace_regs_caller) would not
>    return to <func_prolog+12> but would rather jump to the new function.
>    So, "REG_L ra, -SZREG(sp)" would not run and the original return
>    address would not be restored. The kernel is likely to hang or crash
>    as a result. (Found by Evgenii Shatokhin [4])
> 
> [...]

Here is the summary with links:
  - [-next,V7,1/7] riscv: ftrace: Fixup panic by disabling preemption
    https://git.kernel.org/riscv/c/8547649981e6
  - [-next,V7,2/7] riscv: ftrace: Remove wasted nops for !RISCV_ISA_C
    https://git.kernel.org/riscv/c/409c8fb20c66
  - [-next,V7,3/7] riscv: ftrace: Reduce the detour code size to half
    https://git.kernel.org/riscv/c/6724a76cff85
  - [-next,V7,4/7] riscv: ftrace: Add ftrace_graph_func
    (no matching commit)
  - [-next,V7,5/7] riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support
    (no matching commit)
  - [-next,V7,6/7] samples: ftrace: Add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI]
    (no matching commit)
  - [-next,V7,7/7] riscv : select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
    (no matching commit)

You are awesome, thank you!
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