From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
scottwood@freescale.com
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 3/5] powerpc/8xx: dont save CR in SCRATCH registers
Date: Wed, 4 Feb 2015 15:49:08 +0100 (CET) [thread overview]
Message-ID: <20150204144908.D5E051A5F27@localhost.localdomain> (raw)
CR only needs to be preserved when checking if we are handling a kernel address.
So we can preserve CR in a register:
- In ITLBMiss, check is done only when CONFIG_MODULES is defined. Otherwise we
don't need to do anything at all with CR.
- We use r10, then we reload SRR0/MD_EPN into r10 when CR is restored
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: removed the CPU6 specific handling of CR which was saving (only) 1 cycle but
was making the code more difficult to maintain due to too many different cases
v3: no change (but impacted by patch 07)
v4: Respined against scootwood.git next (0dc294f7)
arch/powerpc/kernel/head_8xx.S | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5a69c5e..150d03f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -312,10 +312,6 @@ InstructionTLBMiss:
mtspr SPRN_DAR, r3
#endif
EXCEPTION_PROLOG_0
- mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_SRR0 /* Get effective address of fault */
- INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
@@ -323,13 +319,20 @@ InstructionTLBMiss:
#ifdef CONFIG_MODULES
/* Only modules will cause ITLB Misses as we always
* pin the first 8MB of kernel memory */
- andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
-#endif
+ mfspr r11, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r10, r11)
+ mfcr r10
+ andis. r11, r11, 0x8000 /* Address >= 0x80000000 */
mfspr r11, SPRN_M_TW /* Get level 1 table */
-#ifdef CONFIG_MODULES
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+#else
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
+ mfspr r11, SPRN_M_TW /* Get level 1 table base address */
#endif
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
@@ -362,8 +365,6 @@ InstructionTLBMiss:
mfspr r3, SPRN_DAR
mtspr SPRN_DAR, r11 /* Tag DAR */
#endif
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
@@ -374,17 +375,19 @@ DataStoreTLBMiss:
#endif
EXCEPTION_PROLOG_0
mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_MD_EPN
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
- andis. r11, r10, 0x8000
+ mfspr r11, SPRN_MD_EPN
+ andis. r11, r11, 0x8000
mfspr r11, SPRN_M_TW /* Get level 1 table */
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_MD_EPN
+
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
@@ -438,8 +441,6 @@ DataStoreTLBMiss:
mfspr r3, SPRN_DAR
#endif
mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
--
2.1.0
reply other threads:[~2015-02-04 14:49 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20150204144908.D5E051A5F27@localhost.localdomain \
--to=christophe.leroy@c-s.fr \
--cc=benh@kernel.crashing.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
--cc=scottwood@freescale.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).