From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Guo Ren <guoren@linux.alibaba.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-riscv@lists.infradead.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: ftrace: Fix to pass correct ftrace_regs to ftrace_func_t functions
Date: Mon, 16 Oct 2023 00:47:19 +0900 [thread overview]
Message-ID: <20231016004719.64c6a762f90826632b2eeaa1@kernel.org> (raw)
In-Reply-To: <20231015231523.901bee54f885a7bb72e1f021@kernel.org>
Hi,
Sorry please ignore this. I found that the arch/riscv doesn't support
HAVE_DYNAMIC_FTRACE_WITH_ARGS. Thus this might add a new feature support.
Let me update it.
Thank you,
On Sun, 15 Oct 2023 23:15:23 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> Hi,
>
> Gentry ping.
>
> I think this should be an important fix because if a fprobe handler without
> FTRACE_OPS_FL_SAVE_REGS tries to access any register via ftrace_regs, that
> will get a wrong value.
>
> Thank you,
>
> On Mon, 2 Oct 2023 21:50:34 +0900
> "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
>
> > From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> >
> > Since ftrace_func_t requires to pass 'struct ftrace_regs *' as the 4th
> > argument even if FTRACE_OPS_FL_SAVE_REGS is not set, ftrace_caller must
> > pass 'struct ftrace_regs *', which is a partial pt_regs, on the stack
> > to the ftrace_func_t functions, so that the ftrace_func_t functions can
> > access some partial registers.
> >
> > Fix to allocate 'struct ftrace_regs' (which has the same size of 'struct
> > pt_regs') on the stack and save partial (argument) registers on it
> > instead of reduced size custom data structure.
> >
> > Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > ---
> > arch/riscv/kernel/mcount-dyn.S | 65 +++++++++++++++++-----------------------
> > 1 file changed, 28 insertions(+), 37 deletions(-)
> >
> > diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
> > index 669b8697aa38..84963680eff4 100644
> > --- a/arch/riscv/kernel/mcount-dyn.S
> > +++ b/arch/riscv/kernel/mcount-dyn.S
> > @@ -14,46 +14,37 @@
> > .text
> >
> > #define FENTRY_RA_OFFSET 8
> > -#define ABI_SIZE_ON_STACK 80
> > -#define ABI_A0 0
> > -#define ABI_A1 8
> > -#define ABI_A2 16
> > -#define ABI_A3 24
> > -#define ABI_A4 32
> > -#define ABI_A5 40
> > -#define ABI_A6 48
> > -#define ABI_A7 56
> > -#define ABI_T0 64
> > -#define ABI_RA 72
> >
> > .macro SAVE_ABI
> > - addi sp, sp, -ABI_SIZE_ON_STACK
> > -
> > - REG_S a0, ABI_A0(sp)
> > - REG_S a1, ABI_A1(sp)
> > - REG_S a2, ABI_A2(sp)
> > - REG_S a3, ABI_A3(sp)
> > - REG_S a4, ABI_A4(sp)
> > - REG_S a5, ABI_A5(sp)
> > - REG_S a6, ABI_A6(sp)
> > - REG_S a7, ABI_A7(sp)
> > - REG_S t0, ABI_T0(sp)
> > - REG_S ra, ABI_RA(sp)
> > + addi sp, sp, -PT_SIZE_ON_STACK
> > +
> > + /* Save t0 as epc for ftrace_regs_get_instruction_pointer() */
> > + REG_S t0, PT_EPC(sp)
> > + REG_S a0, PT_A0(sp)
> > + REG_S a1, PT_A1(sp)
> > + REG_S a2, PT_A2(sp)
> > + REG_S a3, PT_A3(sp)
> > + REG_S a4, PT_A4(sp)
> > + REG_S a5, PT_A5(sp)
> > + REG_S a6, PT_A6(sp)
> > + REG_S a7, PT_A7(sp)
> > + REG_S t0, PT_T0(sp)
> > + REG_S ra, PT_RA(sp)
> > .endm
> >
> > .macro RESTORE_ABI
> > - REG_L a0, ABI_A0(sp)
> > - REG_L a1, ABI_A1(sp)
> > - REG_L a2, ABI_A2(sp)
> > - REG_L a3, ABI_A3(sp)
> > - REG_L a4, ABI_A4(sp)
> > - REG_L a5, ABI_A5(sp)
> > - REG_L a6, ABI_A6(sp)
> > - REG_L a7, ABI_A7(sp)
> > - REG_L t0, ABI_T0(sp)
> > - REG_L ra, ABI_RA(sp)
> > -
> > - addi sp, sp, ABI_SIZE_ON_STACK
> > + REG_L a0, PT_A0(sp)
> > + REG_L a1, PT_A1(sp)
> > + REG_L a2, PT_A2(sp)
> > + REG_L a3, PT_A3(sp)
> > + REG_L a4, PT_A4(sp)
> > + REG_L a5, PT_A5(sp)
> > + REG_L a6, PT_A6(sp)
> > + REG_L a7, PT_A7(sp)
> > + REG_L t0, PT_T0(sp)
> > + REG_L ra, PT_RA(sp)
> > +
> > + addi sp, sp, PT_SIZE_ON_STACK
> > .endm
> >
> > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
> > @@ -96,8 +87,8 @@ ftrace_call:
> > call ftrace_stub
> >
> > #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> > - addi a0, sp, ABI_RA
> > - REG_L a1, ABI_T0(sp)
> > + addi a0, sp, PT_RA
> > + REG_L a1, PT_T0(sp)
> > addi a1, a1, -FENTRY_RA_OFFSET
> > #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
> > mv a2, s0
> >
> >
>
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
prev parent reply other threads:[~2023-10-15 15:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-02 12:50 [PATCH] riscv: ftrace: Fix to pass correct ftrace_regs to ftrace_func_t functions Masami Hiramatsu (Google)
2023-10-15 14:15 ` Masami Hiramatsu
2023-10-15 15:47 ` Masami Hiramatsu [this message]
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