[PATCH] parisc: Fix set_fixmap() on PA1.x CPUs

[Helge Deller <deller@gmx.de>]

Upstream commit 6e866a462867b60841202e900f10936a0478608c failed to
apply to kernel v5.2 up to v5.4.
Below is the fixed backport patch.
Please apply to v5.2 up to v5.4.

Thanks,
Helge

--------------------
From: Helge Deller <deller@gmx.de>
Date: Sun, 31 Oct 2021 21:58:12 +0100
Subject: [PATCH] parisc: Fix set_fixmap() on PA1.x CPUs

Upstream commit: 6e866a462867b60841202e900f10936a0478608c

Fix a kernel crash which happens on PA1.x CPUs while initializing the
FTRACE/KPROBE breakpoints.  The PTE table entries for the fixmap area
were not created correctly.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: ccfbc68d41c2 ("parisc: add set_fixmap()/clear_fixmap()")
Cc: stable@vger.kernel.org # v5.2+

diff --git a/arch/parisc/mm/fixmap.c b/arch/parisc/mm/fixmap.c
index 474cd241c150..02e19a32e6c5 100644
--- a/arch/parisc/mm/fixmap.c
+++ b/arch/parisc/mm/fixmap.c
@@ -18,12 +18,9 @@ void notrace set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
 	pte_t *pte;

 	if (pmd_none(*pmd))
-		pmd = pmd_alloc(NULL, pgd, vaddr);
-
-	pte = pte_offset_kernel(pmd, vaddr);
-	if (pte_none(*pte))
 		pte = pte_alloc_kernel(pmd, vaddr);

+	pte = pte_offset_kernel(pmd, vaddr);
 	set_pte_at(&init_mm, vaddr, pte, __mk_pte(phys, PAGE_KERNEL_RWX));
 	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
 }