[PATCH 11/13] x86_64: Remove pointless set_64bit() usage

Peter Zijlstra
2022-10-22T11:49:15Z

The use of set_64bit() in X86_64 only code is pretty pointless, seeing
how it's a direct assignment. Remove all this nonsense.

Additionally, since x86_64 unconditionally has HAVE_CMPXCHG_DOUBLE,
there is no point in even having that fallback.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/um/include/asm/pgtable-3level.h | 8 --------
arch/x86/include/asm/cmpxchg_64.h | 5 -----
drivers/iommu/intel/irq_remapping.c | 10 ++--------
3 files changed, 2 insertions(+), 21 deletions(-)

--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -58,11 +58,7 @@
#define pud_populate(mm, pud, pmd) \
set_pud(pud, __pud(_PAGE_TABLE + __pa(pmd)))

-#ifdef CONFIG_64BIT
-#define set_pud(pudptr, pudval) set_64bit((u64 *) (pudptr), pud_val(pudval))
-#else
#define set_pud(pudptr, pudval) (*(pudptr) = (pudval))
-#endif

static inline int pgd_newpage(pgd_t pgd)
{
@@ -71,11 +67,7 @@ static inline int pgd_newpage(pgd_t pgd)

static inline void pgd_mkuptodate(pgd_t pgd) { pgd_val(pgd) &= ~_PAGE_NEWPAGE; }

-#ifdef CONFIG_64BIT
-#define set_pmd(pmdptr, pmdval) set_64bit((u64 *) (pmdptr), pmd_val(pmdval))
-#else
#define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
-#endif

static inline void pud_clear (pud_t *pud)
{
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -2,11 +2,6 @@
#ifndef _ASM_X86_CMPXCHG_64_H
#define _ASM_X86_CMPXCHG_64_H

-static inline void set_64bit(volatile u64 *ptr, u64 val)
-{
- *ptr = val;
-}
-
#define arch_cmpxchg64(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -173,7 +173,6 @@ static int modify_irte(struct irq_2_iomm
index = irq_iommu->irte_index + irq_iommu->sub_handle;
irte = &iommu->ir_table->base[index];

-#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)
if ((irte->pst == 1) || (irte_modified->pst == 1)) {
bool ret;

@@ -187,11 +186,6 @@ static int modify_irte(struct irq_2_iomm
* same as the old value.
*/
WARN_ON(!ret);
- } else
-#endif
- {
- set_64bit(&irte->low, irte_modified->low);
- set_64bit(&irte->high, irte_modified->high);
}
__iommu_flush_cache(iommu, irte, sizeof(*irte));

@@ -249,8 +243,8 @@ static int clear_entries(struct irq_2_io
end = start + (1 << irq_iommu->irte_mask);

for (entry = start; entry < end; entry++) {
- set_64bit(&entry->low, 0);
- set_64bit(&entry->high, 0);
+ WRITE_ONCE(entry->low, 0);
+ WRITE_ONCE(entry->high, 0);
}
bitmap_release_region(iommu->ir_table->bitmap, index,
irq_iommu->irte_mask);