powerpc/code-patching: Fix unmap_patch_area() error handling

pXd_offset() doesn't return NULL. When the base is NULL, it
still adds the offset.

Use pXd_none() to check validity instead. It also improves
performance by folding out none existing levels as pXd_none()
always returns 0 in that case.

Such an error is unexpected, use WARN_ON() so that the caller
doesn't have to worry about it, and drop the returned value.

And now that unmap_patch_area() doesn't return error, we can
take into account the error returned by __patch_instruction().

While at it, remove the 'inline' property which is useless.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/299804b117fae35c786c827536c91f25352e279b.1638446239.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 380c55d2e41a060a8b7eb9025efc71ec44e8922d..740ba0dc5da03f362b34659baacf432d933f331f 100644 (file)
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -94,7 +94,7 @@ static int map_patch_area(void *addr, unsigned long text_poke_addr)
        return map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
 }
 
-static inline int unmap_patch_area(unsigned long addr)
+static void unmap_patch_area(unsigned long addr)
 {
        pte_t *ptep;
        pmd_t *pmdp;
@@ -103,32 +103,30 @@ static inline int unmap_patch_area(unsigned long addr)
        pgd_t *pgdp;
 
        pgdp = pgd_offset_k(addr);
-       if (unlikely(!pgdp))
-               return -EINVAL;
+       if (WARN_ON(pgd_none(*pgdp)))
+               return;
 
        p4dp = p4d_offset(pgdp, addr);
-       if (unlikely(!p4dp))
-               return -EINVAL;
+       if (WARN_ON(p4d_none(*p4dp)))
+               return;
 
        pudp = pud_offset(p4dp, addr);
-       if (unlikely(!pudp))
-               return -EINVAL;
+       if (WARN_ON(pud_none(*pudp)))
+               return;
 
        pmdp = pmd_offset(pudp, addr);
-       if (unlikely(!pmdp))
-               return -EINVAL;
+       if (WARN_ON(pmd_none(*pmdp)))
+               return;
 
        ptep = pte_offset_kernel(pmdp, addr);
-       if (unlikely(!ptep))
-               return -EINVAL;
+       if (WARN_ON(pte_none(*ptep)))
+               return;
 
        /*
         * In hash, pte_clear flushes the tlb, in radix, we have to
         */
        pte_clear(&init_mm, addr, ptep);
        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
-
-       return 0;
 }
 
 static int do_patch_instruction(u32 *addr, ppc_inst_t instr)
@@ -156,11 +154,9 @@ static int do_patch_instruction(u32 *addr, ppc_inst_t instr)
 
        patch_addr = (u32 *)(text_poke_addr + (kaddr & ~PAGE_MASK));
 
-       __patch_instruction(addr, instr, patch_addr);
+       err = __patch_instruction(addr, instr, patch_addr);
 
-       err = unmap_patch_area(text_poke_addr);
-       if (err)
-               pr_warn("failed to unmap %lx\n", text_poke_addr);
+       unmap_patch_area(text_poke_addr);
 
 out:
        local_irq_restore(flags);