From: Dmitry Safonov <dsafonov@virtuozzo.com>
To: <linux-kernel@vger.kernel.org>
Cc: <0x7f454c46@gmail.com>, <linux-mm@kvack.org>, <mingo@redhat.com>,
<luto@amacapital.net>, <gorcunov@openvz.org>,
<xemul@virtuozzo.com>, <oleg@redhat.com>,
Dmitry Safonov <dsafonov@virtuozzo.com>,
Andy Lutomirski <luto@kernel.org>, <x86@kernel.org>
Subject: [PATCHv2 5/6] x86/ptrace: down with test_thread_flag(TIF_IA32)
Date: Wed, 29 Jun 2016 13:57:35 +0300 [thread overview]
Message-ID: <20160629105736.15017-6-dsafonov@virtuozzo.com> (raw)
In-Reply-To: <20160629105736.15017-1-dsafonov@virtuozzo.com>
As the task isn't executing at the moment of {GET,SET}REGS,
return regset that corresponds to code selector, rather than
value of TIF_IA32 flag.
I.e. if we ptrace i386 elf binary that has just changed it's
code selector to __USER_CS, than GET_REGS will return
full x86_64 register set.
Note, that this will work only if application has changed it's CS.
If the application does 32-bit syscall with __USER_CS, ptrace
will still return 64-bit register set. Which might be still confusing
for tools that expect TS_COMPACT to be exposed [1, 2].
So this this change should make PTRACE_GETREGSET more reliable and
this will be another step to drop TIF_{IA32,X32} flags.
[1]: https://sourceforge.net/p/strace/mailman/message/30471411/
[2]: https://lkml.org/lkml/2012/1/18/320
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: x86@kernel.org
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
---
arch/x86/kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 600edd225e81..a2612d06cf4b 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1355,7 +1355,7 @@ void update_regset_xstate_info(unsigned int size, u64 xstate_mask)
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_IA32_EMULATION
- if (test_tsk_thread_flag(task, TIF_IA32))
+ if (!user_64bit_mode(task_pt_regs(task)))
#endif
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
return &user_x86_32_view;
--
2.9.0
next prev parent reply other threads:[~2016-06-29 11:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-29 10:57 [PATCHv2 0/6] x86: 32-bit compatible C/R on x86_64 Dmitry Safonov
2016-06-29 10:57 ` [PATCHv2 1/6] x86/vdso: unmap vdso blob on vvar mapping failure Dmitry Safonov
2016-07-06 14:16 ` Andy Lutomirski
2016-06-29 10:57 ` [PATCHv2 2/6] x86/vdso: introduce do_map_vdso() and vdso_type enum Dmitry Safonov
2016-07-06 14:21 ` Andy Lutomirski
2016-07-07 11:04 ` Dmitry Safonov
2016-06-29 10:57 ` [PATCHv2 3/6] x86/arch_prctl/vdso: add ARCH_MAP_VDSO_* Dmitry Safonov
2016-07-06 14:30 ` Andy Lutomirski
2016-07-07 11:11 ` Dmitry Safonov
2016-07-10 12:44 ` Andy Lutomirski
2016-07-11 18:26 ` Oleg Nesterov
2016-07-11 18:28 ` Andy Lutomirski
2016-07-12 14:14 ` Oleg Nesterov
2016-08-02 10:59 ` Dmitry Safonov
2016-08-10 8:35 ` Andy Lutomirski
2016-08-10 10:49 ` Dmitry Safonov
2016-06-29 10:57 ` [PATCHv2 4/6] x86/coredump: use pr_reg size, rather that TIF_IA32 flag Dmitry Safonov
2016-06-29 10:57 ` Dmitry Safonov [this message]
2016-07-06 14:32 ` [PATCHv2 5/6] x86/ptrace: down with test_thread_flag(TIF_IA32) Andy Lutomirski
2016-06-29 10:57 ` [PATCHv2 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Dmitry Safonov
2016-07-06 14:36 ` Andy Lutomirski
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