[PATCH v2] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure

[PATCH v2] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure

[Christophe Leroy]

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
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/mm/nohash/8xx.c | 3 +++
 1 file changed, 3 insertions(+)

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

Re: [PATCH v2] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure

[Michael Ellerman]

On Mon, 2020-04-20 at 05:37:42 UTC, Christophe Leroy wrote:
> 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
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/b61c38baa98056d4802ff5be5cfb979efc2d0f7a

cheers