x86/boot/64: Use RIP_REL_REF() to access early_dynamic_pgts[]

early_dynamic_pgts[] and next_early_pgt are accessed from code that
executes from a 1:1 mapping so it cannot use a plain access from C.
Replace the use of fixup_pointer() with RIP_REL_REF(), which is better
and simpler.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240221113506.2565718-21-ardb+git@google.com

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f98f5b6a06b54d4ff1564f6385847ab82d32a596..2ac904110f6a7ac3c72afa92e2a0be6fed38ca19 100644 (file)
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -170,6 +170,7 @@ static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdv
 unsigned long __head __startup_64(unsigned long physaddr,
                                  struct boot_params *bp)
 {
+       pmd_t (*early_pgts)[PTRS_PER_PMD] = RIP_REL_REF(early_dynamic_pgts);
        unsigned long load_delta, *p;
        unsigned long pgtable_flags;
        pgdval_t *pgd;
@@ -179,7 +180,6 @@ unsigned long __head __startup_64(unsigned long physaddr,
        pteval_t *mask_ptr;
        bool la57;
        int i;
-       unsigned int *next_pgt_ptr;
 
        la57 = check_la57_support(physaddr);
 
@@ -231,15 +231,14 @@ unsigned long __head __startup_64(unsigned long physaddr,
         * it avoids problems around wraparound.
         */
 
-       next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
-       pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
-       pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
+       pud = &early_pgts[0]->pmd;
+       pmd = &early_pgts[1]->pmd;
+       RIP_REL_REF(next_early_pgt) = 2;
 
        pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 
        if (la57) {
-               p4d = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++],
-                                   physaddr);
+               p4d = &early_pgts[RIP_REL_REF(next_early_pgt)++]->pmd;
 
                i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
                pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;