From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, "Andy Lutomirski" <luto@kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>,
"Rik van Riel" <riel@surriel.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>
Subject: [PATCH 06/27] x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()
Date: Wed, 3 Apr 2019 18:41:35 +0200 [thread overview]
Message-ID: <20190403164156.19645-7-bigeasy@linutronix.de> (raw)
In-Reply-To: <20190403164156.19645-1-bigeasy@linutronix.de>
In commit
72a671ced66db ("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels")
the 32bit and 64bit path of the signal delivery code were merged. The 32bit version:
|int save_i387_xstate_ia32(void __user *buf)
|…
| if (cpu_has_xsave)
| return save_i387_xsave(fp);
| if (cpu_has_fxsr)
| return save_i387_fxsave(fp);
The 64bit version:
|int save_i387_xstate(void __user *buf)
|…
| if (user_has_fpu()) {
| if (use_xsave())
| err = xsave_user(buf);
| else
| err = fxsave_user(buf);
|
| if (unlikely(err)) {
| __clear_user(buf, xstate_size);
| return err;
The merge:
|int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
|…
| if (user_has_fpu()) {
| /* Save the live register state to the user directly. */
| if (save_user_xstate(buf_fx))
| return -1;
| /* Update the thread's fxstate to save the fsave header. */
| if (ia32_fxstate)
| fpu_fxsave(&tsk->thread.fpu);
I don't think that we needed to save the FPU registers to ->thread.fpu because
the registers were stored in `buf_fx'. Today the state will be restored from
`buf_fx' after the signal was handled (I assume that this was also the case
with lazy-FPU). Since commit
66463db4fc560 ("x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal()")
it is ensured that the signal handler starts with clear/fresh set of FPU
registers which means that the previous store is futile.
Remove copy_fxregs_to_kernel() because task's FPU state is cleared later in
handle_signal() via fpu__clear().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/fpu/signal.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index de83d0ed9e14e..2f044021fde2b 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -155,7 +155,6 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
- struct fpu *fpu = ¤t->thread.fpu;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);
@@ -173,9 +172,6 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
- /* Update the thread's fxstate to save the fsave header. */
- if (ia32_fxstate)
- copy_fxregs_to_kernel(fpu);
/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
--
2.20.1
next prev parent reply other threads:[~2019-04-03 16:45 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 16:41 [PATCH v9 00/27] x86: load FPU registers on return to userland Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 01/27] x86/fpu: Remove fpu->initialized usage in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-13 20:46 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 02/27] x86/fpu: Remove fpu__restore() Sebastian Andrzej Siewior
2019-04-13 20:47 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 03/27] x86/fpu: Remove preempt_disable() in fpu__clear() Sebastian Andrzej Siewior
2019-04-13 20:48 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 04/27] x86/fpu: Always init the `state' " Sebastian Andrzej Siewior
2019-04-13 20:48 ` [tip:x86/fpu] x86/fpu: Always init the state " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 05/27] x86/fpu: Remove fpu->initialized usage in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 20:49 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` Sebastian Andrzej Siewior [this message]
2019-04-13 20:50 ` [tip:x86/fpu] x86/fpu: Don't save fxregs for ia32 frames " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 07/27] x86/fpu: Remove fpu->initialized Sebastian Andrzej Siewior
2019-04-13 20:50 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 08/27] x86/fpu: Remove user_fpu_begin() Sebastian Andrzej Siewior
2019-04-13 20:51 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 09/27] x86/fpu: Add (__)make_fpregs_active helpers Sebastian Andrzej Siewior
2019-04-13 20:52 ` [tip:x86/fpu] x86/fpu: Add an __fpregs_load_activate() internal helper tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 10/27] x86/fpu: Make __raw_xsave_addr() use feature number instead of mask Sebastian Andrzej Siewior
2019-04-13 20:52 ` [tip:x86/fpu] x86/fpu: Make __raw_xsave_addr() use a " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 11/27] x86/fpu: Make get_xsave_field_ptr() and get_xsave_addr() use " Sebastian Andrzej Siewior
2019-04-13 20:53 ` [tip:x86/fpu] x86/fpu: Use a feature number instead of mask in two more helpers tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 12/27] x86/pkru: Provide .*_pkru_ins() functions Sebastian Andrzej Siewior
2019-04-10 16:36 ` Borislav Petkov
2019-04-10 16:52 ` Borislav Petkov
2019-04-10 21:25 ` Sebastian Andrzej Siewior
2019-04-10 21:29 ` Dave Hansen
2019-04-11 13:24 ` Borislav Petkov
2019-04-13 20:54 ` [tip:x86/fpu] x86/pkeys: Provide *pkru() helpers tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 13/27] x86/fpu: Only write PKRU if it is different from current Sebastian Andrzej Siewior
2019-04-13 20:55 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 14/27] x86/pkeys: Don't check if PKRU is zero before writting it Sebastian Andrzej Siewior
2019-04-13 20:55 ` [tip:x86/fpu] x86/pkeys: Don't check if PKRU is zero before writing it tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 15/27] x86/fpu: Eager switch PKRU state Sebastian Andrzej Siewior
2019-04-13 20:56 ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 16/27] x86/entry: Add TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-04-13 20:57 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 17/27] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 20:57 ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 18/27] x86/fpu: Prepare copy_fpstate_to_sigframe() for TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-04-13 20:58 ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 19/27] x86/fpu: Update xstate's PKRU value on write_pkru() Sebastian Andrzej Siewior
2019-04-08 18:14 ` Dave Hansen
2019-04-08 20:03 ` Sebastian Andrzej Siewior
2019-04-13 20:59 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 20/27] x86/fpu: Inline copy_user_to_fpregs_zeroing() Sebastian Andrzej Siewior
2019-04-13 21:00 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 21/27] x86/fpu: Let __fpu__restore_sig() restore the !32bit+fxsr frame from kernel memory Sebastian Andrzej Siewior
2019-04-13 21:00 ` [tip:x86/fpu] x86/fpu: Restore from kernel memory on the 64-bit path too tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 22/27] x86/fpu: Merge the two code paths in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-13 21:01 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 23/27] x86/fpu: Defer FPU state load until return to userspace Sebastian Andrzej Siewior
2019-04-12 14:36 ` Borislav Petkov
2019-04-12 15:24 ` Sebastian Andrzej Siewior
2019-04-12 16:22 ` Borislav Petkov
2019-04-12 16:37 ` Sebastian Andrzej Siewior
2019-04-12 16:48 ` Borislav Petkov
2019-04-12 17:19 ` Sebastian Andrzej Siewior
2019-04-12 17:29 ` Borislav Petkov
2019-04-15 9:14 ` Sebastian Andrzej Siewior
2019-04-13 21:02 ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 24/27] x86/fpu: Add a fastpath to __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-08 17:05 ` Thomas Gleixner
2019-04-08 20:02 ` Sebastian Andrzej Siewior
2019-04-09 7:27 ` Thomas Gleixner
2019-04-12 17:17 ` Borislav Petkov
2019-04-12 17:27 ` Sebastian Andrzej Siewior
2019-04-13 21:02 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 25/27] x86/fpu: Add a fastpath to copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 21:03 ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 26/27] x86/fpu: Restore FPU register in copy_fpstate_to_sigframe() in order to use the fastpath Sebastian Andrzej Siewior
2019-04-13 21:04 ` [tip:x86/fpu] x86/fpu: Restore regs " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 27/27] x86/pkeys: add PKRU value to init_fpstate Sebastian Andrzej Siewior
2019-04-13 21:05 ` [tip:x86/fpu] x86/pkeys: Add " tip-bot for Sebastian Andrzej Siewior
2019-04-04 14:01 ` [PATCH v9 00/27] x86: load FPU registers on return to userland David Laight
2019-04-04 14:14 ` 'Sebastian Andrzej Siewior'
2019-04-04 14:26 ` Andy Lutomirski
2019-04-04 14:31 ` Sebastian Andrzej Siewior
2019-04-04 15:10 ` David Laight
2019-04-08 17:08 ` Thomas Gleixner
2019-04-12 18:30 ` Borislav Petkov
2019-04-15 8:58 ` Sebastian Andrzej Siewior
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190403164156.19645-7-bigeasy@linutronix.de \
--to=bigeasy@linutronix.de \
--cc=Jason@zx2c4.com \
--cc=dave.hansen@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pbonzini@redhat.com \
--cc=riel@surriel.com \
--cc=rkrcmar@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).