From: Cyril Bur <cyrilbur@gmail.com>
To: linuxppc-dev@ozlabs.org
Cc: mikey@neuling.org, anton@samba.org
Subject: [PATCH v3 6/9] powerpc: Prepare for splitting giveup_{fpu, altivec, vsx} in two
Date: Thu, 21 Jan 2016 11:55:46 +1100 [thread overview]
Message-ID: <1453337749-15506-7-git-send-email-cyrilbur@gmail.com> (raw)
In-Reply-To: <1453337749-15506-1-git-send-email-cyrilbur@gmail.com>
This prepares for the decoupling of saving {fpu,altivec,vsx} registers and
marking {fpu,altivec,vsx} as being unused by a thread.
Currently giveup_{fpu,altivec,vsx}() does both however optimisations to
task switching can be made if these two operations are decoupled.
save_all() will permit the saving of registers to thread structs and leave
threads MSR with bits enabled.
This patch introduces no functional change.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
---
arch/powerpc/include/asm/switch_to.h | 7 +++++++
arch/powerpc/kernel/process.c | 39 +++++++++++++++++++++++++++++++++++-
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 5b268b6..3690041 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -34,6 +34,7 @@ static inline void disable_kernel_fp(void)
msr_check_and_clear(MSR_FP);
}
#else
+static inline void __giveup_fpu(struct task_struct *t) { }
static inline void flush_fp_to_thread(struct task_struct *t) { }
#endif
@@ -46,6 +47,8 @@ static inline void disable_kernel_altivec(void)
{
msr_check_and_clear(MSR_VEC);
}
+#else
+static inline void __giveup_altivec(struct task_struct *t) { }
#endif
#ifdef CONFIG_VSX
@@ -57,6 +60,8 @@ static inline void disable_kernel_vsx(void)
{
msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}
+#else
+static inline void __giveup_vsx(struct task_struct *t) { }
#endif
#ifdef CONFIG_SPE
@@ -68,6 +73,8 @@ static inline void disable_kernel_spe(void)
{
msr_check_and_clear(MSR_SPE);
}
+#else
+static inline void __giveup_spe(struct task_struct *t) { }
#endif
static inline void clear_task_ebb(struct task_struct *t)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 0955b7c..45e37c0 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -349,6 +349,14 @@ void flush_spe_to_thread(struct task_struct *tsk)
preempt_enable();
}
}
+#else
+/*
+ * save_all() is going to test MSR_SPE, rather than pull in all the
+ * booke definitions all the time on a books kernel just ensure it exists
+ * but acts as a nop.
+ */
+
+#define MSR_SPE 0
#endif /* CONFIG_SPE */
static unsigned long msr_all_available;
@@ -440,12 +448,41 @@ void restore_math(struct pt_regs *regs)
regs->msr = msr;
}
+void save_all(struct task_struct *tsk)
+{
+ unsigned long usermsr;
+
+ if (!tsk->thread.regs)
+ return;
+
+ usermsr = tsk->thread.regs->msr;
+
+ if ((usermsr & msr_all_available) == 0)
+ return;
+
+ msr_check_and_set(msr_all_available);
+
+ if (usermsr & MSR_FP)
+ __giveup_fpu(tsk);
+
+ if (usermsr & MSR_VEC)
+ __giveup_altivec(tsk);
+
+ if (usermsr & MSR_VSX)
+ __giveup_vsx(tsk);
+
+ if (usermsr & MSR_SPE)
+ __giveup_spe(tsk);
+
+ msr_check_and_clear(msr_all_available);
+}
+
void flush_all_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
BUG_ON(tsk != current);
- giveup_all(tsk);
+ save_all(tsk);
#ifdef CONFIG_SPE
if (tsk->thread.regs->msr & MSR_SPE)
--
2.7.0
next prev parent reply other threads:[~2016-01-21 0:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-21 0:55 [PATCH v3 0/9] FP/VEC/VSX switching optimisations Cyril Bur
2016-01-21 0:55 ` [PATCH v3 1/9] selftests/powerpc: Test the preservation of FPU and VMX regs across syscall Cyril Bur
2016-02-10 8:56 ` [v3, " Michael Ellerman
2016-01-21 0:55 ` [PATCH v3 2/9] selftests/powerpc: Test preservation of FPU and VMX regs across preemption Cyril Bur
2016-01-21 0:55 ` [PATCH v3 3/9] selftests/powerpc: Test FPU and VMX regs in signal ucontext Cyril Bur
2016-01-21 0:55 ` [PATCH v3 4/9] powerpc: Explicitly disable math features when copying thread Cyril Bur
2016-01-25 0:04 ` Balbir Singh
2016-01-26 23:50 ` Cyril Bur
2016-01-27 12:01 ` Balbir Singh
2016-02-09 0:45 ` Cyril Bur
2016-01-21 0:55 ` [PATCH v3 5/9] powerpc: Restore FPU/VEC/VSX if previously used Cyril Bur
2016-01-21 0:55 ` Cyril Bur [this message]
2016-02-10 7:51 ` [v3, 6/9] powerpc: Prepare for splitting giveup_{fpu, altivec, vsx} in two Michael Ellerman
2016-01-21 0:55 ` [PATCH v3 7/9] powerpc: Add the ability to save FPU without giving it up Cyril Bur
2016-01-21 0:55 ` [PATCH v3 8/9] powerpc: Add the ability to save Altivec " Cyril Bur
2016-01-21 0:55 ` [PATCH v3 9/9] powerpc: Add the ability to save VSX " Cyril Bur
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=1453337749-15506-7-git-send-email-cyrilbur@gmail.com \
--to=cyrilbur@gmail.com \
--cc=anton@samba.org \
--cc=linuxppc-dev@ozlabs.org \
--cc=mikey@neuling.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).