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 --- v3: Use _PAGE_PRESENT directly as all platforms have the bit
v2: Add comment to SET_MEMORY_P and SET_MEMORY_NP --- arch/powerpc/include/asm/set_memory.h | 12 ++++++++- arch/powerpc/mm/pageattr.c | 39 +++++---------------------- arch/powerpc/mm/pgtable_32.c | 24 ++++++++--------- 3 files changed, 28 insertions(+), 47 deletions(-)
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 8812454e70ff..85753e32a4de 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_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX); break; + case SET_MEMORY_NP: + pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0); + break; + case SET_MEMORY_P: + pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0); + break; default: WARN_ON_ONCE(1); break; @@ -90,36 +96,3 @@ 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 */
Hi Michael,
Can we get this series in fixes as well ?
Thanks Christophe
Le 24/12/2021 à 12:07, Christophe Leroy a écrit :
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
v3: Use _PAGE_PRESENT directly as all platforms have the bit
v2: Add comment to SET_MEMORY_P and SET_MEMORY_NP
arch/powerpc/include/asm/set_memory.h | 12 ++++++++- arch/powerpc/mm/pageattr.c | 39 +++++---------------------- arch/powerpc/mm/pgtable_32.c | 24 ++++++++--------- 3 files changed, 28 insertions(+), 47 deletions(-)
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 8812454e70ff..85753e32a4de 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_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX); break;
- case SET_MEMORY_NP:
pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0);break;- case SET_MEMORY_P:
pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0);break;@@ -90,36 +96,3 @@ 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.
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);
set_memory_attr(addr, numpages, __pgprot(0));
set_memory_np(addr, numpages);
linux-stable-mirror@lists.linaro.org
-
Christophe Leroy