2020-04-20 05:30:40

by Christophe Leroy

Subject: [PATCH] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure

WRITE_RO lkdtm test works.

But when selecting CONFIG_DEBUG_RODATA_TEST, the kernel reports
rodata_test: test data was not read only

This is because when rodata test runs, there are still old entries
in TLB.

Flush TLB after setting kernel pages RO or NX.

Fixes: d5f17ee96447 ("powerpc/8xx: don't disable large TLBs with CONFIG_STRICT_KERNEL_RWX")
Cc: [email protected]
Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/kvm/Makefile | 2 +-
arch/powerpc/mm/nohash/8xx.c | 3 +++
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
index 2bfeaa13befb..906707d15810 100644
--- a/arch/powerpc/kvm/Makefile
+++ b/arch/powerpc/kvm/Makefile
@@ -135,4 +135,4 @@ obj-$(CONFIG_KVM_BOOK3S_32) += kvm.o
obj-$(CONFIG_KVM_BOOK3S_64_PR) += kvm-pr.o
obj-$(CONFIG_KVM_BOOK3S_64_HV) += kvm-hv.o

-obj-y += $(kvm-book3s_64-builtin-objs-y)
+obj-$(CONFIG_KVM_BOOK3S_64) += $(kvm-book3s_64-builtin-objs-y)
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 3189308dece4..d83a12c5bc7f 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -185,6 +185,7 @@ void mmu_mark_initmem_nx(void)
mmu_mapin_ram_chunk(etext8, einittext8, PAGE_KERNEL);
}
}
+ _tlbil_all();
}

#ifdef CONFIG_STRICT_KERNEL_RWX
@@ -199,6 +200,8 @@ void mmu_mark_rodata_ro(void)
~(LARGE_PAGE_SIZE_8M - 1)));
mmu_patch_addis(&patch__dtlbmiss_romem_top, -__pa(_sinittext));

+ _tlbil_all();
+
/* Update page tables for PTDUMP and BDI */
mmu_mapin_ram_chunk(0, sinittext, __pgprot(0));
mmu_mapin_ram_chunk(0, etext, PAGE_KERNEL_ROX);
--
2.25.0

2020-04-20 05:38:04

by Christophe Leroy

Subject: Re: [PATCH] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure

Le 20/04/2020 à 07:29, Christophe Leroy a écrit :
> WRITE_RO lkdtm test works.
>
> But when selecting CONFIG_DEBUG_RODATA_TEST, the kernel reports
> rodata_test: test data was not read only
>
> This is because when rodata test runs, there are still old entries
> in TLB.
>
> Flush TLB after setting kernel pages RO or NX.
>
> Fixes: d5f17ee96447 ("powerpc/8xx: don't disable large TLBs with CONFIG_STRICT_KERNEL_RWX")
> Cc: [email protected]
> Signed-off-by: Christophe Leroy <[email protected]>
> ---
> arch/powerpc/kvm/Makefile | 2 +-

Oops, this change shouldn't be there. Will send v2.

> arch/powerpc/mm/nohash/8xx.c | 3 +++
> 2 files changed, 4 insertions(+), 1 deletion(-)


Christophe