From: Conor Dooley <conor@kernel.org>
To: guoren@kernel.org
Cc: anup@brainfault.org, paul.walmsley@sifive.com,
palmer@dabbelt.com, conor.dooley@microchip.com, heiko@sntech.de,
rostedt@goodmis.org, mhiramat@kernel.org, jolsa@redhat.com,
bp@suse.de, jpoimboe@kernel.org, suagrfillet@gmail.com,
andy.chiu@sifive.com, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 1/5] riscv: ftrace: Fixup panic by disabling preemption
Date: Wed, 23 Nov 2022 20:07:20 +0000 [thread overview]
Message-ID: <Y359eOOrm/lpDHjt@spud> (raw)
In-Reply-To: <20221123153950.2911981-2-guoren@kernel.org>
On Wed, Nov 23, 2022 at 10:39:46AM -0500, guoren@kernel.org wrote:
> From: Andy Chiu <andy.chiu@sifive.com>
>
> In RISCV, we must use an AUIPC + JALR pair to encode an immediate,
> forming a jump that jumps to an address over 4K. This may cause errors
> if we want to enable kernel preemption and remove dependency from
> patching code with stop_machine(). For example, if a task was switched
> out on auipc. And, if we changed the ftrace function before it was
> switched back, then it would jump to an address that has updated 11:0
> bits mixing with previous XLEN:12 part.
>
> p: patched area performed by dynamic ftrace
> ftrace_prologue:
> p| REG_S ra, -SZREG(sp)
> p| auipc ra, 0x? ------------> preempted
> ...
> change ftrace function
> ...
> p| jalr -?(ra) <------------- switched back
> p| REG_L ra, -SZREG(sp)
> func:
> xxx
> ret
>
> Fixes: fc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
==========
verify_fixes - FAILED
Commit: be26b864dac9 ("riscv: ftrace: Fixup panic by disabling preemption")
Fixes tag: Fixes: fc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
Has these problem(s):
- Target SHA1 does not exist
This should instead be:
Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
Thanks,
Conor.
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next prev parent reply other threads:[~2022-11-23 20:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-23 15:39 [PATCH V3 0/5] riscv: ftrace: Fixup ftrace detour code & Optimization guoren
2022-11-23 15:39 ` [PATCH V3 1/5] riscv: ftrace: Fixup panic by disabling preemption guoren
2022-11-23 20:07 ` Conor Dooley [this message]
2022-11-24 2:10 ` Guo Ren
2022-11-23 15:39 ` [PATCH V3 2/5] riscv: ftrace: Remove wasted nops for !RISCV_ISA_C guoren
2022-11-23 15:39 ` [PATCH V3 3/5] riscv: ftrace: Reduce the detour code size to half guoren
2022-11-23 20:00 ` Conor Dooley
2022-11-24 2:11 ` Guo Ren
2022-11-23 15:39 ` [PATCH V3 4/5] riscv: ftrace: Add ftrace_graph_func guoren
2022-11-23 15:39 ` [PATCH V3 5/5] riscv: ftrace: Make ftrace_caller call ftrace_graph_func guoren
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