The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b61c38baa98056d4802ff5be5cfb979efc2d0f7a Mon Sep 17 00:00:00 2001

From: Christophe Leroy christophe.leroy@c-s.fr Date: Mon, 20 Apr 2020 05:37:42 +0000 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: stable@vger.kernel.org # v5.1+ Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/485caac75f195f18c11eb077b0031fdd2bb7fb9e.158736103...

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);