FAILED: patch "[PATCH] powerpc/8xx: Fix STRICT_KERNEL_RWX startup test failure" failed to apply to 5.4-stable tree

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 <[email protected]>.

thanks,

greg k-h

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

From b61c38baa98056d4802ff5be5cfb979efc2d0f7a Mon Sep 17 00:00:00 2001
From: Christophe Leroy <[email protected]>
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.

index 3189308dece4..d83a12c5bc7f 100644
@@ -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);