| Message ID | 20220808130109.30738-2-ruscur@russell.cc (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/2] powerpc/mm: Move vm_get_page_prot() out of book3s64 code | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | fail | kernel (ppc44x_defconfig, korg-5.5.0, /linux/arch/powerpc/configs/ppc44x-qemu.config) failed at step build. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | fail | sparse (pmac32, ubuntu-21.10, ppc64) failed at step Build. |
| snowpatch_ozlabs/github-powerpc_clang | fail | 4 of 6 jobs failed. |
On 8/8/22 6:31 PM, Russell Currey wrote: > The Hash MMU already supports XOM (i.e. mmap with PROT_EXEC only) > through the execute-only pkey. A PROT_EXEC-only mapping will actually > map to RX, and then the pkey will be applied on top of it. > > Radix doesn't have pkeys, but it does have execute permissions built-in > to the MMU, so all we have to do to support XOM is expose it. > > That's not possible with protection_map being const, so make it RO after > init instead. > > Signed-off-by: Russell Currey <ruscur@russell.cc> > --- > v2: Make protection_map __ro_after_init and set it in an initcall > (v1 didn't work, I tested before rebasing on Anshuman's patches) > > basic test: https://raw.githubusercontent.com/ruscur/junkcode/main/mmap_test.c > > arch/powerpc/include/asm/book3s/64/radix.h | 3 +++ > arch/powerpc/include/asm/pgtable.h | 1 - > arch/powerpc/mm/fault.c | 10 ++++++++++ > arch/powerpc/mm/pgtable.c | 16 +++++++++++++++- > 4 files changed, 28 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h > index 686001eda936..bf316b773d73 100644 > --- a/arch/powerpc/include/asm/book3s/64/radix.h > +++ b/arch/powerpc/include/asm/book3s/64/radix.h > @@ -19,6 +19,9 @@ > #include <asm/cpu_has_feature.h> > #endif > > +/* Execute-only page protections, Hash can use RX + execute-only pkey */ > +#define PAGE_EXECONLY __pgprot(_PAGE_BASE | _PAGE_EXEC) > + > /* An empty PTE can still have a R or C writeback */ > #define RADIX_PTE_NONE_MASK (_PAGE_DIRTY | _PAGE_ACCESSED) > > diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h > index 33f4bf8d22b0..3cbb6de20f9d 100644 > --- a/arch/powerpc/include/asm/pgtable.h > +++ b/arch/powerpc/include/asm/pgtable.h > @@ -60,7 +60,6 @@ extern void paging_init(void); > void poking_init(void); > > extern unsigned long ioremap_bot; > -extern const pgprot_t protection_map[16]; > > /* > * kern_addr_valid is intended to indicate whether an address is a valid > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index 014005428687..887c0cc45ca6 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -270,6 +270,16 @@ static bool access_error(bool is_write, bool is_exec, struct vm_area_struct *vma > return false; > } > > + if (unlikely(!(vma->vm_flags & VM_READ))) { > + /* > + * If we're on Radix, then this could be a read attempt on > + * execute-only memory. On other MMUs, an "exec-only" page > + * will be given RX flags, so this might be redundant. > + */ > + if (radix_enabled()) > + return true; > + } > + > if (unlikely(!vma_is_accessible(vma))) > return true; > /* > diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c > index 0b2bbde5fb65..6e1a6a999c3c 100644 > --- a/arch/powerpc/mm/pgtable.c > +++ b/arch/powerpc/mm/pgtable.c > @@ -475,7 +475,7 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, > EXPORT_SYMBOL_GPL(__find_linux_pte); > > /* Note due to the way vm flags are laid out, the bits are XWR */ > -const pgprot_t protection_map[16] = { > +static pgprot_t protection_map[16] __ro_after_init = { > [VM_NONE] = PAGE_NONE, > [VM_READ] = PAGE_READONLY, > [VM_WRITE] = PAGE_COPY, > @@ -494,6 +494,20 @@ const pgprot_t protection_map[16] = { > [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X > }; > > +#ifdef CONFIG_PPC_RADIX_MMU > +static int __init radix_update_protection_map(void) > +{ > + if (early_radix_enabled()) { > + /* Radix directly supports execute-only page protections */ > + protection_map[VM_EXEC] = PAGE_EXECONLY; > + protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY; > + } > + > + return 0; > +} > +arch_initcall(radix_update_protection_map); Instead of this can we do this in vm_get_page_prot() ? /* EXEC only shared or non shared mapping ? */ if (radix_enabled() && ((vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) == VM_EXEC)) prot = PAGE_EXECONLY; > +#endif /* CONFIG_PPC_RADIX_MMU */ > + > #ifdef CONFIG_PPC_BOOK3S_64 > pgprot_t vm_get_page_prot(unsigned long vm_flags) > {
On Mon, 2022-08-08 at 18:54 +0530, Aneesh Kumar K V wrote: > On 8/8/22 6:31 PM, Russell Currey wrote: > > The Hash MMU already supports XOM (i.e. mmap with PROT_EXEC only) > > through the execute-only pkey. A PROT_EXEC-only mapping will > > actually > > map to RX, and then the pkey will be applied on top of it. > > > > Radix doesn't have pkeys, but it does have execute permissions > > built-in > > to the MMU, so all we have to do to support XOM is expose it. > > > > That's not possible with protection_map being const, so make it RO > > after > > init instead. > > > > Signed-off-by: Russell Currey <ruscur@russell.cc> > > --- > > v2: Make protection_map __ro_after_init and set it in an initcall > > (v1 didn't work, I tested before rebasing on Anshuman's patches) > > > > basic test: > > https://raw.githubusercontent.com/ruscur/junkcode/main/mmap_test.c > > > > arch/powerpc/include/asm/book3s/64/radix.h | 3 +++ > > arch/powerpc/include/asm/pgtable.h | 1 - > > arch/powerpc/mm/fault.c | 10 ++++++++++ > > arch/powerpc/mm/pgtable.c | 16 +++++++++++++++- > > 4 files changed, 28 insertions(+), 2 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/book3s/64/radix.h > > b/arch/powerpc/include/asm/book3s/64/radix.h > > index 686001eda936..bf316b773d73 100644 > > --- a/arch/powerpc/include/asm/book3s/64/radix.h > > +++ b/arch/powerpc/include/asm/book3s/64/radix.h > > @@ -19,6 +19,9 @@ > > #include <asm/cpu_has_feature.h> > > #endif > > > > +/* Execute-only page protections, Hash can use RX + execute-only > > pkey */ > > +#define PAGE_EXECONLY __pgprot(_PAGE_BASE | _PAGE_EXEC) > > + > > /* An empty PTE can still have a R or C writeback */ > > #define RADIX_PTE_NONE_MASK (_PAGE_DIRTY | > > _PAGE_ACCESSED) > > > > diff --git a/arch/powerpc/include/asm/pgtable.h > > b/arch/powerpc/include/asm/pgtable.h > > index 33f4bf8d22b0..3cbb6de20f9d 100644 > > --- a/arch/powerpc/include/asm/pgtable.h > > +++ b/arch/powerpc/include/asm/pgtable.h > > @@ -60,7 +60,6 @@ extern void paging_init(void); > > void poking_init(void); > > > > extern unsigned long ioremap_bot; > > -extern const pgprot_t protection_map[16]; > > > > /* > > * kern_addr_valid is intended to indicate whether an address is a > > valid > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > > index 014005428687..887c0cc45ca6 100644 > > --- a/arch/powerpc/mm/fault.c > > +++ b/arch/powerpc/mm/fault.c > > @@ -270,6 +270,16 @@ static bool access_error(bool is_write, bool > > is_exec, struct vm_area_struct *vma > > return false; > > } > > > > + if (unlikely(!(vma->vm_flags & VM_READ))) { > > + /* > > + * If we're on Radix, then this could be a read > > attempt on > > + * execute-only memory. On other MMUs, an "exec- > > only" page > > + * will be given RX flags, so this might be > > redundant. > > + */ > > + if (radix_enabled()) > > + return true; > > + } > > + > > if (unlikely(!vma_is_accessible(vma))) > > return true; > > /* > > diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c > > index 0b2bbde5fb65..6e1a6a999c3c 100644 > > --- a/arch/powerpc/mm/pgtable.c > > +++ b/arch/powerpc/mm/pgtable.c > > @@ -475,7 +475,7 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned > > long ea, > > EXPORT_SYMBOL_GPL(__find_linux_pte); > > > > /* Note due to the way vm flags are laid out, the bits are XWR */ > > -const pgprot_t protection_map[16] = { > > +static pgprot_t protection_map[16] __ro_after_init = { > > [VM_NONE] = > > PAGE_NONE, > > [VM_READ] = > > PAGE_READONLY, > > [VM_WRITE] = > > PAGE_COPY, > > @@ -494,6 +494,20 @@ const pgprot_t protection_map[16] = { > > [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = > > PAGE_SHARED_X > > }; > > > > +#ifdef CONFIG_PPC_RADIX_MMU > > +static int __init radix_update_protection_map(void) > > +{ > > + if (early_radix_enabled()) { > > + /* Radix directly supports execute-only page > > protections */ > > + protection_map[VM_EXEC] = PAGE_EXECONLY; > > + protection_map[VM_EXEC | VM_SHARED] = > > PAGE_EXECONLY; > > + } > > + > > + return 0; > > +} > > +arch_initcall(radix_update_protection_map); > > Instead of this can we do this in vm_get_page_prot() ? > > /* EXEC only shared or non shared mapping ? */ > if (radix_enabled() && ((vm_flags & (VM_READ | VM_WRITE | > VM_EXEC)) == VM_EXEC)) > prot = PAGE_EXECONLY; That is a lot simpler, thanks. - Russell > > > > +#endif /* CONFIG_PPC_RADIX_MMU */ > > + > > #ifdef CONFIG_PPC_BOOK3S_64 > > pgprot_t vm_get_page_prot(unsigned long vm_flags) > > { >
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h index 686001eda936..bf316b773d73 100644 --- a/arch/powerpc/include/asm/book3s/64/radix.h +++ b/arch/powerpc/include/asm/book3s/64/radix.h @@ -19,6 +19,9 @@ #include <asm/cpu_has_feature.h> #endif +/* Execute-only page protections, Hash can use RX + execute-only pkey */ +#define PAGE_EXECONLY __pgprot(_PAGE_BASE | _PAGE_EXEC) + /* An empty PTE can still have a R or C writeback */ #define RADIX_PTE_NONE_MASK (_PAGE_DIRTY | _PAGE_ACCESSED) diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index 33f4bf8d22b0..3cbb6de20f9d 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -60,7 +60,6 @@ extern void paging_init(void); void poking_init(void); extern unsigned long ioremap_bot; -extern const pgprot_t protection_map[16]; /* * kern_addr_valid is intended to indicate whether an address is a valid diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 014005428687..887c0cc45ca6 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -270,6 +270,16 @@ static bool access_error(bool is_write, bool is_exec, struct vm_area_struct *vma return false; } + if (unlikely(!(vma->vm_flags & VM_READ))) { + /* + * If we're on Radix, then this could be a read attempt on + * execute-only memory. On other MMUs, an "exec-only" page + * will be given RX flags, so this might be redundant. + */ + if (radix_enabled()) + return true; + } + if (unlikely(!vma_is_accessible(vma))) return true; /* diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 0b2bbde5fb65..6e1a6a999c3c 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -475,7 +475,7 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, EXPORT_SYMBOL_GPL(__find_linux_pte); /* Note due to the way vm flags are laid out, the bits are XWR */ -const pgprot_t protection_map[16] = { +static pgprot_t protection_map[16] __ro_after_init = { [VM_NONE] = PAGE_NONE, [VM_READ] = PAGE_READONLY, [VM_WRITE] = PAGE_COPY, @@ -494,6 +494,20 @@ const pgprot_t protection_map[16] = { [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X }; +#ifdef CONFIG_PPC_RADIX_MMU +static int __init radix_update_protection_map(void) +{ + if (early_radix_enabled()) { + /* Radix directly supports execute-only page protections */ + protection_map[VM_EXEC] = PAGE_EXECONLY; + protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY; + } + + return 0; +} +arch_initcall(radix_update_protection_map); +#endif /* CONFIG_PPC_RADIX_MMU */ + #ifdef CONFIG_PPC_BOOK3S_64 pgprot_t vm_get_page_prot(unsigned long vm_flags) {
The Hash MMU already supports XOM (i.e. mmap with PROT_EXEC only) through the execute-only pkey. A PROT_EXEC-only mapping will actually map to RX, and then the pkey will be applied on top of it. Radix doesn't have pkeys, but it does have execute permissions built-in to the MMU, so all we have to do to support XOM is expose it. That's not possible with protection_map being const, so make it RO after init instead. Signed-off-by: Russell Currey <ruscur@russell.cc> --- v2: Make protection_map __ro_after_init and set it in an initcall (v1 didn't work, I tested before rebasing on Anshuman's patches) basic test: https://raw.githubusercontent.com/ruscur/junkcode/main/mmap_test.c arch/powerpc/include/asm/book3s/64/radix.h | 3 +++ arch/powerpc/include/asm/pgtable.h | 1 - arch/powerpc/mm/fault.c | 10 ++++++++++ arch/powerpc/mm/pgtable.c | 16 +++++++++++++++- 4 files changed, 28 insertions(+), 2 deletions(-)