[PATCH v5 03/16] x86/startup_64: Use RIP_REL_REF() to access early_dynamic_pgts[]

Ard Biesheuvel
2024-02-21T11:35:43Z

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>
---
arch/x86/kernel/head64.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f98f5b6a06b5..2ac904110f6a 100644
--- 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;
--
2.44.0.rc0.258.g7320e95886-goog