From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Michael Schmitz <schmitzmic@gmail.com>
Cc: Linux-Arch <linux-arch@vger.kernel.org>,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andreas Schwab <schwab@linux-m68k.org>
Subject: Re: [PATCH v4 3/3] m68k: track syscalls being traced with shallow user context stack
Date: Sun, 25 Jul 2021 12:05:26 +0200 [thread overview]
Message-ID: <CAMuHMdVA5d7z6awGrpJ+Tb3PRxz7Nczd_SLXZ=cAwsS8tFU_vg@mail.gmail.com> (raw)
In-Reply-To: <1624407696-20180-4-git-send-email-schmitzmic@gmail.com>
Hi Michael,
On Wed, Jun 23, 2021 at 2:21 AM Michael Schmitz <schmitzmic@gmail.com> wrote:
> Add 'status' field to thread_info struct to hold syscall trace
> status info.
>
> Set flag bit in thread_info->status at syscall trace entry, clear
> flag bit on trace exit.
>
> Set another flag bit on entering syscall where the full stack
> frame has been saved. These flags can be checked whenever a
> syscall calls ptrace_stop().
>
> Check flag bits in get_reg()/put_reg() and prevent access to
> registers that are saved on the switch stack, in case the
> syscall did not actually save these registers on the switch
> stack.
>
> Tested on ARAnyM only - boots and survives running strace on a
> binary, nothing fancy.
>
> CC: Eric W. Biederman <ebiederm@xmission.com>
> CC: Linus Torvalds <torvalds@linux-foundation.org>
> CC: Andreas Schwab <schwab@linux-m68k.org>
> Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
Thanks for your patch!
> --- a/arch/m68k/kernel/entry.S
> +++ b/arch/m68k/kernel/entry.S
> @@ -51,75 +51,115 @@
>
> .text
> ENTRY(__sys_fork)
> + movel %curptr@(TASK_STACK),%a1
> + orb #TIS_SWITCH_STACK, %a1@(TINFO_STATUS+3)
This doesn't work on Coldfire:
arch/m68k/kernel/entry.S:55: Error: invalid instruction for this
architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001,
68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k,
68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32
[68330, 68331, 68332,
68333, 68334, 68336, 68340, 68341, 68349, 68360], fidoa [fido]) --
statement `orb #(1<<1),%a1@(16+3)' ignored
> SAVE_SWITCH_STACK
> jbsr sys_fork
> lea %sp@(24),%sp
> + movel %curptr@(TASK_STACK),%a1
> + andb #TIS_NO_SWITCH_STACK, %a1@(TINFO_STATUS+3)
arch/m68k/kernel/entry.S:60: Error: invalid instruction for this
architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001,
68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k,
68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32
[68330, 68331, 68332, 68333, 68334, 68336, 68340, 68341, 68349,
68360], fidoa [fido]) -- statement `andb #(~((1<<1))),%a1@(16+3)'
ignored
> rts
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2021-07-25 10:05 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 0:21 [PATCH v4 0/3] m68k: Improved switch stack handling Michael Schmitz
2021-06-23 0:21 ` [PATCH v4 1/3] m68k: save extra registers on more syscall entry points Michael Schmitz
2021-06-23 0:21 ` [PATCH v4 2/3] m68k: correctly handle IO worker stack frame set-up Michael Schmitz
2021-06-23 0:21 ` [PATCH v4 3/3] m68k: track syscalls being traced with shallow user context stack Michael Schmitz
2021-07-25 10:05 ` Geert Uytterhoeven [this message]
2021-07-25 20:48 ` Michael Schmitz
2021-07-25 21:00 ` Linus Torvalds
2021-07-26 14:27 ` Greg Ungerer
2021-07-15 13:29 ` [PATCH v4 0/3] m68k: Improved switch stack handling Eric W. Biederman
2021-07-15 23:10 ` Michael Schmitz
2021-07-17 5:38 ` Michael Schmitz
2021-07-17 18:52 ` Eric W. Biederman
2021-07-17 20:09 ` Michael Schmitz
2021-07-17 23:04 ` Michael Schmitz
2021-07-18 10:47 ` Andreas Schwab
2021-07-18 19:47 ` Michael Schmitz
2021-07-18 20:59 ` Brad Boyer
2021-07-19 3:15 ` Michael Schmitz
2021-07-20 20:32 ` Eric W. Biederman
2021-07-20 22:16 ` Michael Schmitz
2021-07-22 14:49 ` Eric W. Biederman
2021-07-23 4:23 ` Michael Schmitz
2021-07-23 22:31 ` Eric W. Biederman
2021-07-23 23:52 ` Michael Schmitz
2021-07-24 12:05 ` Andreas Schwab
2021-07-25 7:44 ` Michael Schmitz
2021-07-25 10:12 ` Brad Boyer
2021-07-26 2:00 ` Michael Schmitz
2021-07-26 19:36 ` [RFC][PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die Eric W. Biederman
2021-07-26 20:13 ` Andreas Schwab
2021-07-26 20:29 ` Eric W. Biederman
2021-07-26 21:25 ` Andreas Schwab
2021-07-26 20:29 ` Michael Schmitz
2021-07-26 21:08 ` [PATCH] " Eric W. Biederman
2021-08-25 15:56 ` Eric W. Biederman
2021-08-26 12:15 ` Geert Uytterhoeven
2021-07-25 11:53 ` [PATCH v4 0/3] m68k: Improved switch stack handling Andreas Schwab
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