From: Guo Ren <guoren@kernel.org>
To: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: "Patrick Stählin" <me@packi.ch>,
"Guo Ren" <guoren@linux.alibaba.com>,
"Anup Patel" <anup@brainfault.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-csky@vger.kernel.org, "Oleg Nesterov" <oleg@redhat.com>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Zong Li" <zong.li@sifive.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Greentime Hu" <greentime.hu@sifive.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
"Bjorn Topel" <bjorn.topel@gmail.com>
Subject: Re: [PATCH v3 3/7] riscv: Fixup kprobes handler couldn't change pc
Date: Mon, 17 Aug 2020 20:47:21 +0800 [thread overview]
Message-ID: <CAJF2gTTz_EFpzMoT3yBgCNTNme9_QbQ9b2dGZB3S0F5+O6Fpyw@mail.gmail.com> (raw)
In-Reply-To: <mhng-296dd63e-71de-4d30-acfb-df374d12388d@palmerdabbelt-glaptop1>
On Sat, Aug 15, 2020 at 6:36 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> On Mon, 13 Jul 2020 16:39:18 PDT (-0700), guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > The "Changing Execution Path" section in the Documentation/kprobes.txt
> > said:
> >
> > Since kprobes can probe into a running kernel code, it can change the
> > register set, including instruction pointer.
> >
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Cc: Masami Hiramatsu <mhiramat@kernel.org>
> > Cc: Palmer Dabbelt <palmerdabbelt@google.com>
> > ---
> > arch/riscv/kernel/mcount-dyn.S | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
> > index 35a6ed7..4b58b54 100644
> > --- a/arch/riscv/kernel/mcount-dyn.S
> > +++ b/arch/riscv/kernel/mcount-dyn.S
> > @@ -123,6 +123,7 @@ ENDPROC(ftrace_caller)
> > sd ra, (PT_SIZE_ON_STACK+8)(sp)
> > addi s0, sp, (PT_SIZE_ON_STACK+16)
> >
> > + sd ra, PT_EPC(sp)
> > sd x1, PT_RA(sp)
> > sd x2, PT_SP(sp)
> > sd x3, PT_GP(sp)
>
> So that's definately not going to be EPC any more. I'm not sure that field is
> sanely named, though, as it's really just the PC when it comes to other ptrace
> stuff.
>
> > @@ -157,6 +158,7 @@ ENDPROC(ftrace_caller)
> > .endm
> >
> > .macro RESTORE_ALL
> > + ld ra, PT_EPC(sp)
> > ld x1, PT_RA(sp)
>
> x1 is ra, so loading it twice doesn't seem reasonable.
>
> > ld x2, PT_SP(sp)
> > ld x3, PT_GP(sp)
> > @@ -190,7 +192,6 @@ ENDPROC(ftrace_caller)
> > ld x31, PT_T6(sp)
> >
> > ld s0, (PT_SIZE_ON_STACK)(sp)
> > - ld ra, (PT_SIZE_ON_STACK+8)(sp)
> > addi sp, sp, (PT_SIZE_ON_STACK+16)
> > .endm
>
> If you're dropping the load you should drop the store above as well. In
> general this seems kind of mixed up, both before and after this patch.
This is a wrong patch, it should be:
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
index 35a6ed7..d82b8f0 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S
@@ -120,10 +120,10 @@ ENDPROC(ftrace_caller)
.macro SAVE_ALL
addi sp, sp, -(PT_SIZE_ON_STACK+16)
sd s0, (PT_SIZE_ON_STACK)(sp)
- sd ra, (PT_SIZE_ON_STACK+8)(sp)
addi s0, sp, (PT_SIZE_ON_STACK+16)
- sd x1, PT_RA(sp)
+ sd ra, PT_EPC(sp)
+ sd ra, PT_RA(sp)
sd x2, PT_SP(sp)
sd x3, PT_GP(sp)
sd x4, PT_TP(sp)
@@ -157,7 +157,7 @@ ENDPROC(ftrace_caller)
.endm
.macro RESTORE_ALL
- ld x1, PT_RA(sp)
+ ld ra, PT_EPC(sp)
ld x2, PT_SP(sp)
ld x3, PT_GP(sp)
ld x4, PT_TP(sp)
@@ -190,7 +190,6 @@ ENDPROC(ftrace_caller)
ld x31, PT_T6(sp)
ld s0, (PT_SIZE_ON_STACK)(sp)
- ld ra, (PT_SIZE_ON_STACK+8)(sp)
addi sp, sp, (PT_SIZE_ON_STACK+16)
.endm
Now, I'm developing livepatch and they are so mixed features (kprobe,
livepatch, ftrace, optprobes, STACK_WALK, -fpatchable-function-entry
'no -pg'). I'll test this patch in the next version of the patchset.
Thx for the review.
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2020-08-17 12:47 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 23:39 [PATCH v3 0/7] riscv: Add k/uprobe supported guoren
2020-07-13 23:39 ` [PATCH v3 1/7] RISC-V: Implement ptrace regs and stack API guoren
2020-07-14 11:25 ` Masami Hiramatsu
2020-07-13 23:39 ` [PATCH v3 2/7] riscv: Fixup compile error BUILD_BUG_ON failed guoren
2020-07-13 23:39 ` [PATCH v3 3/7] riscv: Fixup kprobes handler couldn't change pc guoren
2020-07-14 11:32 ` Masami Hiramatsu
2020-08-14 22:36 ` Palmer Dabbelt
2020-08-17 12:47 ` Guo Ren [this message]
2020-07-13 23:39 ` [PATCH v3 4/7] riscv: Add kprobes supported guoren
2020-08-14 22:36 ` Palmer Dabbelt
2020-08-17 13:48 ` Guo Ren
2020-07-13 23:39 ` [PATCH v3 5/7] riscv: Add uprobes supported guoren
2020-07-13 23:39 ` [PATCH v3 6/7] riscv: Add KPROBES_ON_FTRACE supported guoren
2020-07-14 11:37 ` Masami Hiramatsu
2020-07-14 16:24 ` Guo Ren
2020-07-21 13:27 ` Masami Hiramatsu
2020-07-22 8:39 ` Guo Ren
2020-07-23 15:55 ` Masami Hiramatsu
2020-07-22 13:31 ` Guo Ren
2020-07-23 16:11 ` Masami Hiramatsu
2020-07-13 23:39 ` [PATCH v3 7/7] riscv: Add support for function error injection guoren
2020-07-14 11:43 ` Masami Hiramatsu
2020-07-14 11:23 ` [PATCH v3 0/7] riscv: Add k/uprobe supported Masami Hiramatsu
2020-07-15 6:45 ` Guo Ren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAJF2gTTz_EFpzMoT3yBgCNTNme9_QbQ9b2dGZB3S0F5+O6Fpyw@mail.gmail.com \
--to=guoren@kernel.org \
--cc=anup@brainfault.org \
--cc=bjorn.topel@gmail.com \
--cc=greentime.hu@sifive.com \
--cc=guoren@linux.alibaba.com \
--cc=linux-csky@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=me@packi.ch \
--cc=mhiramat@kernel.org \
--cc=oleg@redhat.com \
--cc=palmerdabbelt@google.com \
--cc=paul.walmsley@sifive.com \
--cc=zong.li@sifive.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).