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Subject[PATCHv2 5/6] 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.


Cc: Oleg Nesterov <>
Cc: Andy Lutomirski <>
Cc: Ingo Molnar <>
Cc: Cyrill Gorcunov <>
Cc: Pavel Emelyanov <>
Signed-off-by: Dmitry Safonov <>
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)
- if (test_tsk_thread_flag(task, TIF_IA32))
+ if (!user_64bit_mode(task_pt_regs(task)))
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
return &user_x86_32_view;
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