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>,
Scott Wood <oss@buserror.net>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/32: Move entry_32 functions just after HEAD functions.
Date: Tue, 18 Apr 2017 09:01:26 +0200 (CEST) [thread overview]
Message-ID: <20170418070126.A18EF67952@localhost.localdomain> (raw)
By default, PPC8xx PINs an ITLB on the first 8M of memory in order
to avoid any ITLB miss on kernel code.
However, with some debug functions like DEBUG_PAGEALLOC and
(soon to come) DEBUG_RODATA, the PINned TLB is invalidated soon
after startup so ITLB missed start to happen also on the kernel code.
In order to avoid any ITLB miss in a critical section, we have to
ensure that their is no page boundary crossed between the setup of
a new value in SRR0/SRR1 and the associated RFI. This cannot be done
easily if entry_32 functions sits in the middle of other .text
functions. By placing entry_32 just after the .head section (as already
done for entry_64 on PPC64), we can more easily ensure the issue
doesn't happen.
Ex: with this change, all entry_32 functions playing with srr0/srr1
appears between 0xc0002000 and 0xc0002fff on PPC_8xx.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/Makefile | 2 +-
arch/powerpc/kernel/Makefile | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 19b0d1a81959..8aa1dafb14eb 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -243,7 +243,7 @@ head-$(CONFIG_40x) := arch/powerpc/kernel/head_40x.o
head-$(CONFIG_44x) := arch/powerpc/kernel/head_44x.o
head-$(CONFIG_FSL_BOOKE) := arch/powerpc/kernel/head_fsl_booke.o
-head-$(CONFIG_PPC64) += arch/powerpc/kernel/entry_64.o
+head-y += arch/powerpc/kernel/entry_$(BITS).o
head-$(CONFIG_PPC_FPU) += arch/powerpc/kernel/fpu.o
head-$(CONFIG_ALTIVEC) += arch/powerpc/kernel/vector.o
head-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += arch/powerpc/kernel/prom_init.o
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 811f441a125f..eb2db44c5fe9 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -90,7 +90,7 @@ extra-y += vmlinux.lds
obj-$(CONFIG_RELOCATABLE) += reloc_$(BITS).o
-obj-$(CONFIG_PPC32) += entry_32.o setup_32.o
+obj-$(CONFIG_PPC32) += setup_32.o
obj-$(CONFIG_PPC64) += dma-iommu.o iommu.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_BOOTX_TEXT) += btext.o
@@ -154,7 +154,7 @@ UBSAN_SANITIZE_vdso.o := n
extra-$(CONFIG_PPC_FPU) += fpu.o
extra-$(CONFIG_ALTIVEC) += vector.o
-extra-$(CONFIG_PPC64) += entry_64.o
+extra-y += entry_$(BITS).o
extra-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += prom_init.o
extra-y += systbl_chk.i
--
2.12.0
next reply other threads:[~2017-04-18 7:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 7:01 Christophe Leroy [this message]
2017-04-19 15:16 ` [PATCH] powerpc/32: Move entry_32 functions just after HEAD functions David Laight
2017-04-20 11:25 ` Michael Ellerman
2017-04-20 11:43 ` Christophe LEROY
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