From: ebiederm@xmission.com (Eric W. Biederman)
To: Michael Schmitz <schmitzmic@gmail.com>
Cc: Brad Boyer <flar@allandria.com>,
Andreas Schwab <schwab@linux-m68k.org>,
geert@linux-m68k.org, linux-arch@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, torvalds@linux-foundation.org
Subject: [RFC][PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
Date: Mon, 26 Jul 2021 14:36:42 -0500 [thread overview]
Message-ID: <87a6m8kgtx.fsf_-_@disp2133> (raw)
In-Reply-To: <be3ddf9a-745e-4798-17a7-a9d0ddd7eef7@gmail.com> (Michael Schmitz's message of "Mon, 26 Jul 2021 14:00:01 +1200")
In the fpsp040 code when copyin or copyout fails call
force_sigsegv(SIGSEGV) instead of do_exit(SIGSEGV).
This solves a couple of problems. Because do_exit embeds the ptrace
stop PTRACE_EVENT_EXIT a complete stack frame needs to be present for
that to work correctly. There is always the information needed for a
ptrace stop where get_signal is called. So exiting with a signal
solves the ptrace issue.
Further exiting with a signal ensures that all of the threads in a
process are killed not just the thread that malfunctioned. Which
avoids confusing userspace.
To make force_sigsegv(SIGSEGV) work in fpsp040_die modify the code to
save all of the registers and jump to ret_from_exception (which
ultimately calls get_signal) after fpsp040_die returns.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
Can someone please check my m68k assembly changes?
I think I have them correct, and the code assembles but I don't
understand the fine points of when the different branch instructions
should be used.
arch/m68k/fpsp040/skeleton.S | 3 ++-
arch/m68k/kernel/traps.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/m68k/fpsp040/skeleton.S b/arch/m68k/fpsp040/skeleton.S
index a8f41615d94a..ec767523c012 100644
--- a/arch/m68k/fpsp040/skeleton.S
+++ b/arch/m68k/fpsp040/skeleton.S
@@ -502,7 +502,8 @@ in_ea:
.section .fixup,#alloc,#execinstr
.even
1:
- jbra fpsp040_die
+ bsrl fpsp040_die
+ jmp .Lnotkern
.section __ex_table,#alloc
.align 4
diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 9e1261462bcc..5b19fcdcd69e 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -1150,7 +1150,7 @@ asmlinkage void set_esp0(unsigned long ssp)
*/
asmlinkage void fpsp040_die(void)
{
- do_exit(SIGSEGV);
+ force_sigsegv(SIGSEGV);
}
#ifdef CONFIG_M68KFPU_EMU
--
2.20.1
next prev parent reply other threads:[~2021-07-26 19:36 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
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 ` Eric W. Biederman [this message]
2021-07-26 20:13 ` [RFC][PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die 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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