x86/mm: Use the correct function type for native_set_fixmap()

BugLink: https://bugs.launchpad.net/bugs/1858462

[ Upstream commit f53e2cd0 ]

We call native_set_fixmap indirectly through the function pointer
struct pv_mmu_ops::set_fixmap, which expects the first parameter to be
'unsigned' instead of 'enum fixed_addresses'. This patch changes the
function type for native_set_fixmap to match the pointer, which fixes
indirect call mismatches with Control-Flow Integrity (CFI) checking.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190913211402.193018-1-samitolvanen@google.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/include/asm/fixmap.h

@@ -147,7 +147,7 @@ extern pgprot_t kmap_prot;
 extern pte_t *pkmap_page_table;
 
 void __native_set_fixmap(enum fixed_addresses idx, pte_t pte);
-void native_set_fixmap(enum fixed_addresses idx,
+void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
 		       phys_addr_t phys, pgprot_t flags);
 
 #ifndef CONFIG_PARAVIRT

arch/x86/mm/pgtable.c

@@ -567,8 +567,8 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
 	fixmaps_set++;
 }
 
-void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
-		       pgprot_t flags)
+void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
+		       phys_addr_t phys, pgprot_t flags)
 {
 	__native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
 }