powerpc: Fail ioremap() instead of silently ignoring flags when PAGE_USER is set

Calling ioremap() with _PAGE_USER (or _PAGE_PRIVILEDGE unset)
is wrong. Loudly fail the call to ioremap() instead of blindly
clearing the flags.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/b6dd5485ad00d2aafd2bb9b7c2c4eac3ebf2cdaf.1695659959.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c
index d5159f20538006ece4a9263d12b49d8352f32899..7823c38f09deeafaae518d3bcef7260274f44886 100644 (file)
--- a/arch/powerpc/mm/ioremap.c
+++ b/arch/powerpc/mm/ioremap.c
@@ -51,7 +51,8 @@ void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long flags)
                pte = pte_mkdirty(pte);
 
        /* we don't want to let _PAGE_USER leak out */
-       pte = pte_mkprivileged(pte);
+       if (WARN_ON(pte_user(pte)))
+               return NULL;
 
        if (iowa_is_active())
                return iowa_ioremap(addr, size, pte_pgprot(pte), caller);