Commit-ID: cc87324b3dbb9bdf6916c7f479230db24c4aa309
Gitweb: http://git.kernel.org/tip/cc87324b3dbb9bdf6916c7f479230db24c4aa309
Author: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
AuthorDate: Mon, 5 Sep 2016 16:33:07 +0300
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 14 Sep 2016 21:28:11 +0200
x86/ptrace: Down with test_thread_flag(TIF_IA32)
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
Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
Cc: 0x7f454c46@xxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: luto@xxxxxxxxxx
Cc: Pedro Alves <palves@xxxxxxxxxx>
Cc: gorcunov@xxxxxxxxxx
Cc: xemul@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160905133308.28234-6-dsafonov@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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 f79576a..ad0bab8 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1358,7 +1358,7 @@ 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;
--
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