From: Rik van Riel <riel@surriel.com>
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, kernel-team@fb.com, will.deacon@arm.com,
songliubraving@fb.com, mingo@kernel.org, luto@kernel.org,
hpa@zytor.com, npiggin@gmail.com, Rik van Riel <riel@surriel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
efault@gmx.de
Subject: [PATCH 2/7] x86/mm/tlb: Restructure switch_mm_irqs_off()
Date: Tue, 25 Sep 2018 23:58:39 -0400 [thread overview]
Message-ID: <20180926035844.1420-3-riel@surriel.com> (raw)
In-Reply-To: <20180926035844.1420-1-riel@surriel.com>
Move some code that will be needed for the lazy -> !lazy state
transition when a lazy TLB CPU has gotten out of date.
No functional changes, since the if (real_prev == next) branch
always returns.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: efault@gmx.de
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20180716190337.26133-4-riel@surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 61d0beb5796ab11f7f3bf38cb2eccc6579aaa70b)
---
arch/x86/mm/tlb.c | 64 ++++++++++++++++++++++++-----------------------
1 file changed, 33 insertions(+), 31 deletions(-)
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 54a5870190a6..1224f7fb1311 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -187,6 +187,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
unsigned cpu = smp_processor_id();
u64 next_tlb_gen;
+ bool need_flush;
+ u16 new_asid;
/*
* NB: The scheduler will call us with prev == next when switching
@@ -308,44 +310,44 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
/* Let nmi_uaccess_okay() know that we're changing CR3. */
this_cpu_write(cpu_tlbstate.loaded_mm, LOADED_MM_SWITCHING);
barrier();
+ }
- if (need_flush) {
- this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
- this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
- load_new_mm_cr3(next->pgd, new_asid, true);
-
- /*
- * NB: This gets called via leave_mm() in the idle path
- * where RCU functions differently. Tracing normally
- * uses RCU, so we need to use the _rcuidle variant.
- *
- * (There is no good reason for this. The idle code should
- * be rearranged to call this before rcu_idle_enter().)
- */
- trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
- } else {
- /* The new ASID is already up to date. */
- load_new_mm_cr3(next->pgd, new_asid, false);
-
- /* See above wrt _rcuidle. */
- trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
- }
+ if (need_flush) {
+ this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
+ this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
+ load_new_mm_cr3(next->pgd, new_asid, true);
/*
- * Record last user mm's context id, so we can avoid
- * flushing branch buffer with IBPB if we switch back
- * to the same user.
+ * NB: This gets called via leave_mm() in the idle path
+ * where RCU functions differently. Tracing normally
+ * uses RCU, so we need to use the _rcuidle variant.
+ *
+ * (There is no good reason for this. The idle code should
+ * be rearranged to call this before rcu_idle_enter().)
*/
- if (next != &init_mm)
- this_cpu_write(cpu_tlbstate.last_ctx_id, next->context.ctx_id);
-
- /* Make sure we write CR3 before loaded_mm. */
- barrier();
+ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
+ } else {
+ /* The new ASID is already up to date. */
+ load_new_mm_cr3(next->pgd, new_asid, false);
- this_cpu_write(cpu_tlbstate.loaded_mm, next);
- this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
+ /* See above wrt _rcuidle. */
+ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
}
+ /*
+ * Record last user mm's context id, so we can avoid
+ * flushing branch buffer with IBPB if we switch back
+ * to the same user.
+ */
+ if (next != &init_mm)
+ this_cpu_write(cpu_tlbstate.last_ctx_id, next->context.ctx_id);
+
+ /* Make sure we write CR3 before loaded_mm. */
+ barrier();
+
+ this_cpu_write(cpu_tlbstate.loaded_mm, next);
+ this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
+
load_mm_cr4(next);
switch_ldt(real_prev, next);
}
--
2.17.1
next prev parent reply other threads:[~2018-09-26 3:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-26 3:58 [PATCH v2 0/7] x86/mm/tlb: make lazy TLB mode even lazier Rik van Riel
2018-09-26 3:58 ` [PATCH 1/7] x86/mm/tlb: Always use lazy TLB mode Rik van Riel
2018-10-01 15:58 ` Peter Zijlstra
2018-10-01 16:07 ` Rik van Riel
2018-09-26 3:58 ` Rik van Riel [this message]
2018-10-02 7:32 ` [PATCH 2/7] x86/mm/tlb: Restructure switch_mm_irqs_off() Peter Zijlstra
2018-09-26 3:58 ` [PATCH 3/7] smp: use __cpumask_set_cpu in on_each_cpu_cond Rik van Riel
2018-10-09 14:59 ` [tip:x86/mm] " tip-bot for Rik van Riel
2018-09-26 3:58 ` [PATCH 4/7] smp,cpumask: introduce on_each_cpu_cond_mask Rik van Riel
2018-10-09 14:59 ` [tip:x86/mm] " tip-bot for Rik van Riel
2018-09-26 3:58 ` [PATCH 5/7] Add freed_tables argument to flush_tlb_mm_range Rik van Riel
2018-10-09 15:00 ` [tip:x86/mm] x86/mm/tlb: " tip-bot for Rik van Riel
2018-09-26 3:58 ` [PATCH 6/7] Add freed_tables element to flush_tlb_info Rik van Riel
2018-10-09 15:00 ` [tip:x86/mm] x86/mm/tlb: " tip-bot for Rik van Riel
2018-09-26 3:58 ` [PATCH 7/7] x86/mm/tlb: Make lazy TLB mode lazier Rik van Riel
2018-10-01 16:07 ` Peter Zijlstra
2018-10-09 15:01 ` [tip:x86/mm] " tip-bot for Rik van Riel
2018-10-01 16:09 ` [PATCH v2 0/7] x86/mm/tlb: make lazy TLB mode even lazier Peter Zijlstra
2018-10-02 7:44 ` Peter Zijlstra
2018-10-02 13:41 ` Rik van Riel
-- strict thread matches above, loose matches on Subject: below --
2018-09-24 18:37 [PATCH " Rik van Riel
2018-09-24 18:37 ` [PATCH 2/7] x86/mm/tlb: Restructure switch_mm_irqs_off() Rik van Riel
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=20180926035844.1420-3-riel@surriel.com \
--to=riel@surriel.com \
--cc=efault@gmx.de \
--cc=hpa@zytor.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@kernel.org \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=songliubraving@fb.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=will.deacon@arm.com \
/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).