| Message ID | 20240813134158.580-3-jgross@suse.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mini-os: mm: use a generic page table walker | expand |
Juergen Gross, le mar. 13 août 2024 15:41:57 +0200, a ecrit: > Instead of open coding a page table walk, use walk_pt() in need_pgt(). > > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> > --- > V2: > - add comment and ASSERT() (Samuel Thibault) > --- > arch/x86/mm.c | 72 +++++++++++++++++++++------------------------------ > 1 file changed, 30 insertions(+), 42 deletions(-) > > diff --git a/arch/x86/mm.c b/arch/x86/mm.c > index 9849b985..84a6d7f0 100644 > --- a/arch/x86/mm.c > +++ b/arch/x86/mm.c > @@ -523,57 +523,45 @@ static pgentry_t *get_pgt(unsigned long va) > * return a valid PTE for a given virtual address. If PTE does not exist, > * allocate page-table pages. > */ > -pgentry_t *need_pgt(unsigned long va) > +static int need_pgt_func(unsigned long va, unsigned int lvl, bool is_leaf, > + pgentry_t *pte, void *par) > { > + pgentry_t **result = par; > unsigned long pt_mfn; > - pgentry_t *tab; > unsigned long pt_pfn; > - unsigned offset; > + unsigned int idx; > > - tab = pt_base; > - pt_mfn = virt_to_mfn(pt_base); > + if ( !is_leaf ) > + return 0; > > -#if defined(__x86_64__) > - offset = l4_table_offset(va); > - if ( !(tab[offset] & _PAGE_PRESENT) ) > - { > - pt_pfn = virt_to_pfn(alloc_page()); > - if ( !pt_pfn ) > - return NULL; > - new_pt_frame(&pt_pfn, pt_mfn, offset, L3_FRAME); > - } > - ASSERT(tab[offset] & _PAGE_PRESENT); > - pt_mfn = pte_to_mfn(tab[offset]); > - tab = mfn_to_virt(pt_mfn); > -#endif > - offset = l3_table_offset(va); > - if ( !(tab[offset] & _PAGE_PRESENT) ) > - { > - pt_pfn = virt_to_pfn(alloc_page()); > - if ( !pt_pfn ) > - return NULL; > - new_pt_frame(&pt_pfn, pt_mfn, offset, L2_FRAME); > - } > - ASSERT(tab[offset] & _PAGE_PRESENT); > - pt_mfn = pte_to_mfn(tab[offset]); > - tab = mfn_to_virt(pt_mfn); > - offset = l2_table_offset(va); > - if ( !(tab[offset] & _PAGE_PRESENT) ) > + if ( lvl == L1_FRAME || (*pte & _PAGE_PRESENT) ) > { > - pt_pfn = virt_to_pfn(alloc_page()); > - if ( !pt_pfn ) > - return NULL; > - new_pt_frame(&pt_pfn, pt_mfn, offset, L1_FRAME); > + /* > + * The PTE is not addressing a page table (is_leaf is true). If we are > + * either at the lowest level or we have a valid large page, we don't > + * need to allocate a page table. > + */ > + ASSERT(lvl == L1_FRAME || (*pte & _PAGE_PSE)); > + *result = pte; > + return 1; > } > - ASSERT(tab[offset] & _PAGE_PRESENT); > - if ( tab[offset] & _PAGE_PSE ) > - return &tab[offset]; > > - pt_mfn = pte_to_mfn(tab[offset]); > - tab = mfn_to_virt(pt_mfn); > + pt_mfn = virt_to_mfn(pte); > + pt_pfn = virt_to_pfn(alloc_page()); > + if ( !pt_pfn ) > + return -1; > + idx = idx_from_va_lvl(va, lvl); > + new_pt_frame(&pt_pfn, pt_mfn, idx, lvl - 1); > > - offset = l1_table_offset(va); > - return &tab[offset]; > + return 0; > +} > + > +pgentry_t *need_pgt(unsigned long va) > +{ > + pgentry_t *tab = NULL; > + > + walk_pt(va, va, need_pgt_func, &tab); > + return tab; > } > EXPORT_SYMBOL(need_pgt); > > -- > 2.43.0 >
diff --git a/arch/x86/mm.c b/arch/x86/mm.c index 9849b985..84a6d7f0 100644 --- a/arch/x86/mm.c +++ b/arch/x86/mm.c @@ -523,57 +523,45 @@ static pgentry_t *get_pgt(unsigned long va) * return a valid PTE for a given virtual address. If PTE does not exist, * allocate page-table pages. */ -pgentry_t *need_pgt(unsigned long va) +static int need_pgt_func(unsigned long va, unsigned int lvl, bool is_leaf, + pgentry_t *pte, void *par) { + pgentry_t **result = par; unsigned long pt_mfn; - pgentry_t *tab; unsigned long pt_pfn; - unsigned offset; + unsigned int idx; - tab = pt_base; - pt_mfn = virt_to_mfn(pt_base); + if ( !is_leaf ) + return 0; -#if defined(__x86_64__) - offset = l4_table_offset(va); - if ( !(tab[offset] & _PAGE_PRESENT) ) - { - pt_pfn = virt_to_pfn(alloc_page()); - if ( !pt_pfn ) - return NULL; - new_pt_frame(&pt_pfn, pt_mfn, offset, L3_FRAME); - } - ASSERT(tab[offset] & _PAGE_PRESENT); - pt_mfn = pte_to_mfn(tab[offset]); - tab = mfn_to_virt(pt_mfn); -#endif - offset = l3_table_offset(va); - if ( !(tab[offset] & _PAGE_PRESENT) ) - { - pt_pfn = virt_to_pfn(alloc_page()); - if ( !pt_pfn ) - return NULL; - new_pt_frame(&pt_pfn, pt_mfn, offset, L2_FRAME); - } - ASSERT(tab[offset] & _PAGE_PRESENT); - pt_mfn = pte_to_mfn(tab[offset]); - tab = mfn_to_virt(pt_mfn); - offset = l2_table_offset(va); - if ( !(tab[offset] & _PAGE_PRESENT) ) + if ( lvl == L1_FRAME || (*pte & _PAGE_PRESENT) ) { - pt_pfn = virt_to_pfn(alloc_page()); - if ( !pt_pfn ) - return NULL; - new_pt_frame(&pt_pfn, pt_mfn, offset, L1_FRAME); + /* + * The PTE is not addressing a page table (is_leaf is true). If we are + * either at the lowest level or we have a valid large page, we don't + * need to allocate a page table. + */ + ASSERT(lvl == L1_FRAME || (*pte & _PAGE_PSE)); + *result = pte; + return 1; } - ASSERT(tab[offset] & _PAGE_PRESENT); - if ( tab[offset] & _PAGE_PSE ) - return &tab[offset]; - pt_mfn = pte_to_mfn(tab[offset]); - tab = mfn_to_virt(pt_mfn); + pt_mfn = virt_to_mfn(pte); + pt_pfn = virt_to_pfn(alloc_page()); + if ( !pt_pfn ) + return -1; + idx = idx_from_va_lvl(va, lvl); + new_pt_frame(&pt_pfn, pt_mfn, idx, lvl - 1); - offset = l1_table_offset(va); - return &tab[offset]; + return 0; +} + +pgentry_t *need_pgt(unsigned long va) +{ + pgentry_t *tab = NULL; + + walk_pt(va, va, need_pgt_func, &tab); + return tab; } EXPORT_SYMBOL(need_pgt);
Instead of open coding a page table walk, use walk_pt() in need_pgt(). Signed-off-by: Juergen Gross <jgross@suse.com> --- V2: - add comment and ASSERT() (Samuel Thibault) --- arch/x86/mm.c | 72 +++++++++++++++++++++------------------------------ 1 file changed, 30 insertions(+), 42 deletions(-)