From: Ingo Molnar <mingo@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave@sr71.net>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Uros Bizjak <ubizjak@gmail.com>
Subject: [PATCH 0/1] Fast headers: Make task_struct::thread constant size
Date: Wed, 20 Mar 2024 14:19:07 +0100 [thread overview]
Message-ID: <20240320131908.2708438-1-mingo@kernel.org> (raw)
Turn thread.fpu into a pointer. Since most FPU code internals work by passing
around the FPU pointer already, the code generation impact is small.
This allows us to remove the old kludge of task_struct being variable size:
struct task_struct {
...
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
*/
randomized_struct_fields_end
/* CPU-specific state of this task: */
struct thread_struct thread;
/*
* WARNING: on x86, 'thread_struct' contains a variable-sized
* structure. It *MUST* be at the end of 'task_struct'.
*
* Do not put anything below here!
*/
};
... which creates a number of problems, such as requiring thread_struct to be
the last member of the struct - not allowing it to be struct-randomized, etc.
But the primary motivation is to allow the decoupling of task_struct from
hardware details (<asm/processor.h> in particular), and to eventually allow
the per-task infrastructure:
DECLARE_PER_TASK(type, name);
...
per_task(current, name) = val;
... which requires task_struct to be a constant size struct.
The fpu_thread_struct_whitelist() quirk to hardened usercopy can be removed,
now that the FPU structure is not embedded in the task struct anymore, which
reduces text footprint a bit.
Ingo Molnar (1):
headers/deps: x86/fpu: Make task_struct::thread constant size
arch/x86/include/asm/fpu/sched.h | 2 +-
arch/x86/include/asm/processor.h | 14 ++++++--------
arch/x86/kernel/fpu/context.h | 4 ++--
arch/x86/kernel/fpu/core.c | 51 ++++++++++++++++++++++++++-------------------------
arch/x86/kernel/fpu/init.c | 28 ++++++++++++++++++----------
arch/x86/kernel/fpu/regset.c | 22 +++++++++++-----------
arch/x86/kernel/fpu/signal.c | 18 +++++++++---------
arch/x86/kernel/fpu/xstate.c | 22 +++++++++++-----------
arch/x86/kernel/fpu/xstate.h | 6 +++---
arch/x86/kernel/process.c | 6 +++---
arch/x86/kernel/signal.c | 6 +++---
arch/x86/kernel/traps.c | 2 +-
arch/x86/math-emu/fpu_aux.c | 2 +-
arch/x86/math-emu/fpu_entry.c | 4 ++--
arch/x86/math-emu/fpu_system.h | 2 +-
arch/x86/mm/extable.c | 2 +-
include/linux/sched.h | 13 +++----------
17 files changed, 102 insertions(+), 102 deletions(-)
--
2.40.1
next reply other threads:[~2024-03-20 13:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-20 13:19 Ingo Molnar [this message]
2024-03-20 13:19 ` [PATCH 1/1] headers/deps: x86/fpu: Make task_struct::thread constant size Ingo Molnar
2024-03-25 6:00 ` kernel test robot
2024-03-26 17:49 ` Oleg Nesterov
2024-03-26 19:12 ` Ingo Molnar
2024-03-26 19:13 ` [PATCH 1/1 -v2] " Ingo Molnar
2024-03-26 21:54 ` [PATCH 1/1] " Oleg Nesterov
2024-03-29 9:10 ` [PATCH 2/1] headers/deps: x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2024-03-29 9:45 ` [PATCH 3/1] x86/fpu: Remove init_task FPU state dependencies, add debugging warning Ingo Molnar
2024-03-29 13:41 ` [tip: x86/fpu] x86/vm86: Make sure the free_vm86(task) definition uses its parameter even in the !CONFIG_VM86 case tip-bot2 for Ingo Molnar
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