set_memory_attr() was implemented by commit 4d1755b6a762 ("powerpc/mm: implement set_memory_attr()") because the set_memory_xx() couldn't be used at that time to modify memory "on the fly" as explained it the commit.

But set_memory_attr() uses set_pte_at() which leads to warnings when CONFIG_DEBUG_VM is selected, because set_pte_at() is unexpected for updating existing page table entries.

The check could be bypassed by using __set_pte_at() instead, as it was the case before commit c988cfd38e48 ("powerpc/32: use set_memory_attr()") but since commit 9f7853d7609d ("powerpc/mm: Fix set_memory_*() against concurrent accesses") it is now possible to use set_memory_xx() functions to update page table entries "on the fly" because the update is now atomic.

For DEBUG_PAGEALLOC we need to clear and set back _PAGE_PRESENT. Add set_memory_np() and set_memory_p() for that.

Replace all uses of set_memory_attr() by the relevant set_memory_xx() and remove set_memory_attr().

Reported-by: Maxime Bizon mbizon@freebox.fr Fixes: c988cfd38e48 ("powerpc/32: use set_memory_attr()") Cc: stable@vger.kernel.org Depends-on: 9f7853d7609d ("powerpc/mm: Fix set_memory_*() against concurrent accesses") Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu Reviewed-by: Russell Currey ruscur@russell.cc Tested-by: Maxime Bizon mbizon@freebox.fr --- v2: Add comment to SET_MEMORY_P and SET_MEMORY_NP --- arch/powerpc/include/asm/book3s/32/pgtable.h | 10 +++++ arch/powerpc/include/asm/book3s/64/pgtable.h | 10 +++++ arch/powerpc/include/asm/nohash/pgtable.h | 10 +++++ arch/powerpc/include/asm/set_memory.h | 12 +++++- arch/powerpc/mm/pageattr.c | 39 +++----------------- arch/powerpc/mm/pgtable_32.c | 24 ++++++------ 6 files changed, 58 insertions(+), 47 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h index 609c80f67194..4ceebb291896 100644 --- a/arch/powerpc/include/asm/book3s/32/pgtable.h +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h @@ -518,6 +518,16 @@ static inline pte_t pte_mkuser(pte_t pte) return __pte(pte_val(pte) | _PAGE_USER); }

+static inline pte_t pte_mkpresent(pte_t pte) +{ + return __pte(pte_val(pte) | _PAGE_PRESENT); +} + +static inline pte_t pte_mkabsent(pte_t pte) +{ + return __pte(pte_val(pte) & ~_PAGE_PRESENT); +} + static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)); diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 33e073d6b0c4..2bbc8b69b7f4 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -724,6 +724,16 @@ static inline pte_t pte_mkuser(pte_t pte) return __pte_raw(pte_raw(pte) & cpu_to_be64(~_PAGE_PRIVILEGED)); }

+static inline pte_t pte_mkpresent(pte_t pte) +{ + return __pte_raw(pte_raw(pte) | cpu_to_be64(_PAGE_PRESENT)); +} + +static inline pte_t pte_mkabsent(pte_t pte) +{ + return __pte_raw(pte_raw(pte) & cpu_to_be64(~_PAGE_PRESENT)); +} + /* * This is potentially called with a pmd as the argument, in which case it's not * safe to check _PAGE_DEVMAP unless we also confirm that _PAGE_PTE is set. diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h index ac75f4ab0dba..3d4169969900 100644 --- a/arch/powerpc/include/asm/nohash/pgtable.h +++ b/arch/powerpc/include/asm/nohash/pgtable.h @@ -166,6 +166,16 @@ static inline pte_t pte_mkuser(pte_t pte) } #endif

+static inline pte_t pte_mkpresent(pte_t pte) +{ + return __pte(pte_val(pte) | _PAGE_PRESENT); +} + +static inline pte_t pte_mkabsent(pte_t pte) +{ + return __pte(pte_val(pte) & ~_PAGE_PRESENT); +} + static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)); diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h index b040094f7920..7ebc807aa8cc 100644 --- a/arch/powerpc/include/asm/set_memory.h +++ b/arch/powerpc/include/asm/set_memory.h @@ -6,6 +6,8 @@ #define SET_MEMORY_RW 1 #define SET_MEMORY_NX 2 #define SET_MEMORY_X 3 +#define SET_MEMORY_NP 4 /* Set memory non present */ +#define SET_MEMORY_P 5 /* Set memory present */

int change_memory_attr(unsigned long addr, int numpages, long action);

@@ -29,6 +31,14 @@ static inline int set_memory_x(unsigned long addr, int numpages) return change_memory_attr(addr, numpages, SET_MEMORY_X); }

-int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot); +static inline int set_memory_np(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_NP); +} + +static inline int set_memory_p(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_P); +}

#endif diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c index 308adc51da9d..eb5405d410f1 100644 --- a/arch/powerpc/mm/pageattr.c +++ b/arch/powerpc/mm/pageattr.c @@ -46,6 +46,12 @@ static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) case SET_MEMORY_X: pte = pte_mkexec(pte); break; + case SET_MEMORY_NP: + pte = pte_mkabsent(pte); + break; + case SET_MEMORY_P: + pte = pte_mkpresent(pte); + break; default: WARN_ON_ONCE(1); break; @@ -92,36 +98,3 @@ int change_memory_attr(unsigned long addr, int numpages, long action) return apply_to_existing_page_range(&init_mm, start, size, change_page_attr, (void *)action); } - -/* - * Set the attributes of a page: - * - * This function is used by PPC32 at the end of init to set final kernel memory - * protection. It includes changing the maping of the page it is executing from - * and data pages it is using. - */ -static int set_page_attr(pte_t *ptep, unsigned long addr, void *data) -{ - pgprot_t prot = __pgprot((unsigned long)data); - - spin_lock(&init_mm.page_table_lock); - - set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot)); - flush_tlb_kernel_range(addr, addr + PAGE_SIZE); - - spin_unlock(&init_mm.page_table_lock); - - return 0; -} - -int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot) -{ - unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); - unsigned long sz = numpages * PAGE_SIZE; - - if (numpages <= 0) - return 0; - - return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr, - (void *)pgprot_val(prot)); -} diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index 906e4e4328b2..f71ededdc02a 100644 --- a/arch/powerpc/mm/pgtable_32.c +++ b/arch/powerpc/mm/pgtable_32.c @@ -135,10 +135,12 @@ void mark_initmem_nx(void) unsigned long numpages = PFN_UP((unsigned long)_einittext) - PFN_DOWN((unsigned long)_sinittext);

- if (v_block_mapped((unsigned long)_sinittext)) + if (v_block_mapped((unsigned long)_sinittext)) { mmu_mark_initmem_nx(); - else - set_memory_attr((unsigned long)_sinittext, numpages, PAGE_KERNEL); + } else { + set_memory_nx((unsigned long)_sinittext, numpages); + set_memory_rw((unsigned long)_sinittext, numpages); + } }

#ifdef CONFIG_STRICT_KERNEL_RWX @@ -152,18 +154,14 @@ void mark_rodata_ro(void) return; }

- numpages = PFN_UP((unsigned long)_etext) - - PFN_DOWN((unsigned long)_stext); - - set_memory_attr((unsigned long)_stext, numpages, PAGE_KERNEL_ROX); /* - * mark .rodata as read only. Use __init_begin rather than __end_rodata - * to cover NOTES and EXCEPTION_TABLE. + * mark .text and .rodata as read only. Use __init_begin rather than + * __end_rodata to cover NOTES and EXCEPTION_TABLE. */ numpages = PFN_UP((unsigned long)__init_begin) - - PFN_DOWN((unsigned long)__start_rodata); + PFN_DOWN((unsigned long)_stext);

- set_memory_attr((unsigned long)__start_rodata, numpages, PAGE_KERNEL_RO); + set_memory_ro((unsigned long)_stext, numpages);

// mark_initmem_nx() should have already run by now ptdump_check_wx(); @@ -179,8 +177,8 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) return;

if (enable) - set_memory_attr(addr, numpages, PAGE_KERNEL); + set_memory_p(addr, numpages); else - set_memory_attr(addr, numpages, __pgprot(0)); + set_memory_np(addr, numpages); } #endif /* CONFIG_DEBUG_PAGEALLOC */