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riscv: pgtable: Use riscv_has_extension_unlikely 

Use riscv_has_extension_unlikely() to check for RISCV_ISA_EXT_SVVPTC,
replacing the use of asm goto with ALTERNATIVE.

The "unlikely" variant is used to match the behavior of the original
implementation using ALTERNATIVE("nop", "j %l[svvptc]", ...).

Note that this makes the check for RISCV_ISA_EXT_SVVPTC a runtime one if
RISCV_ALTERNATIVE=n, but it should still be worthwhile to do so given
that TLB flushes are relatively slow.

Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Link: https://patch.msgid.link/20251020-riscv-altn-helper-wip-v4-1-ef941c87669a@iscas.ac.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Vivian Wang 2025-11-17 21:19:21 -07:00 committed by Paul Walmsley
parent c9a7161044
commit 0a067ae21b
2 changed files with 17 additions and 20 deletions
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15
arch/riscv/include/asm/pgtable.h
View File

@ -496,8 +496,13 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf,
struct vm_area_struct *vma, unsigned long address,
pte_t *ptep, unsigned int nr)
{
asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1)
: : : : svvptc);
/*
* Svvptc guarantees that the new valid pte will be visible within
* a bounded timeframe, so when the uarch does not cache invalid
* entries, we don't have to do anything.
*/
if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SVVPTC))
return;
/*
* The kernel assumes that TLBs don't cache invalid entries, but
@ -509,12 +514,6 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf,
while (nr--)
local_flush_tlb_page(address + nr * PAGE_SIZE);
svvptc:;
/*
* Svvptc guarantees that the new valid pte will be visible within
* a bounded timeframe, so when the uarch does not cache invalid
* entries, we don't have to do anything.
*/
}
#define update_mmu_cache(vma, addr, ptep) \
update_mmu_cache_range(NULL, vma, addr, ptep, 1)

22
arch/riscv/mm/pgtable.c
View File

@ -9,8 +9,16 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty)
{
asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1)
: : : : svvptc);
if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SVVPTC)) {
if (!pte_same(ptep_get(ptep), entry)) {
__set_pte_at(vma->vm_mm, ptep, entry);
/* Here only not svadu is impacted */
flush_tlb_page(vma, address);
return true;
}
return false;
}
if (!pte_same(ptep_get(ptep), entry))
__set_pte_at(vma->vm_mm, ptep, entry);
@ -19,16 +27,6 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
* the case that the PTE changed and the spurious fault case.
*/
return true;
svvptc:
if (!pte_same(ptep_get(ptep), entry)) {
__set_pte_at(vma->vm_mm, ptep, entry);
/* Here only not svadu is impacted */
flush_tlb_page(vma, address);
return true;
}
return false;
}
int ptep_test_and_clear_young(struct vm_area_struct *vma,