* [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping
@ 2012-01-17 16:50 Will Deacon
2012-01-17 19:11 ` Nicolas Pitre
0 siblings, 1 reply; 4+ messages in thread
From: Will Deacon @ 2012-01-17 16:50 UTC (permalink / raw)
To: linux-arm-kernel
The current user mapping for the vectors page is inserted as a `horrible
hack vma' into each task via arch_setup_additional_pages. This causes
problems with the MM subsystem and vm_normal_page, as described here:
https://lkml.org/lkml/2012/1/14/55
Following the suggestion from Hugh in the above thread, this patch uses
the gate_vma for the vectors user mapping, therefore consolidating
the horrible hack VMAs into one.
Cc: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
v2: Removed old arch_{exit,dup}_mmap implementations for ARM.
Tested on vexpress (ctca9x4), PB1176 and AB926.
arch/arm/include/asm/elf.h | 4 ---
arch/arm/include/asm/mmu_context.h | 29 +--------------------------
arch/arm/include/asm/page.h | 2 +
arch/arm/kernel/process.c | 38 ++++++++++++++++++++++++++---------
4 files changed, 31 insertions(+), 42 deletions(-)
diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index 0e9ce8d..38050b1 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -130,8 +130,4 @@ struct mm_struct;
extern unsigned long arch_randomize_brk(struct mm_struct *mm);
#define arch_randomize_brk arch_randomize_brk
-extern int vectors_user_mapping(void);
-#define arch_setup_additional_pages(bprm, uses_interp) vectors_user_mapping()
-#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
-
#endif
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index 71605d9..a0b3cac 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -18,6 +18,7 @@
#include <asm/cacheflush.h>
#include <asm/cachetype.h>
#include <asm/proc-fns.h>
+#include <asm-generic/mm_hooks.h>
void __check_kvm_seq(struct mm_struct *mm);
@@ -133,32 +134,4 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
#define deactivate_mm(tsk,mm) do { } while (0)
#define activate_mm(prev,next) switch_mm(prev, next, NULL)
-/*
- * We are inserting a "fake" vma for the user-accessible vector page so
- * gdb and friends can get to it through ptrace and /proc/<pid>/mem.
- * But we also want to remove it before the generic code gets to see it
- * during process exit or the unmapping of it would cause total havoc.
- * (the macro is used as remove_vma() is static to mm/mmap.c)
- */
-#define arch_exit_mmap(mm) \
-do { \
- struct vm_area_struct *high_vma = find_vma(mm, 0xffff0000); \
- if (high_vma) { \
- BUG_ON(high_vma->vm_next); /* it should be last */ \
- if (high_vma->vm_prev) \
- high_vma->vm_prev->vm_next = NULL; \
- else \
- mm->mmap = NULL; \
- rb_erase(&high_vma->vm_rb, &mm->mm_rb); \
- mm->mmap_cache = NULL; \
- mm->map_count--; \
- remove_vma(high_vma); \
- } \
-} while (0)
-
-static inline void arch_dup_mmap(struct mm_struct *oldmm,
- struct mm_struct *mm)
-{
-}
-
#endif
diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index 97b440c..5838361 100644
--- a/arch/arm/include/asm/page.h
+++ b/arch/arm/include/asm/page.h
@@ -151,6 +151,8 @@ extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
extern void copy_page(void *to, const void *from);
+#define __HAVE_ARCH_GATE_AREA 1
+
#ifdef CONFIG_ARM_LPAE
#include <asm/pgtable-3level-types.h>
#else
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 971d65c..e11b523 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -526,22 +526,40 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
#ifdef CONFIG_MMU
/*
* The vectors page is always readable from user space for the
- * atomic helpers and the signal restart code. Let's declare a mapping
- * for it so it is visible through ptrace and /proc/<pid>/mem.
+ * atomic helpers and the signal restart code. Insert it into the
+ * gate_vma so that it is visible through ptrace and /proc/<pid>/mem.
*/
+static struct vm_area_struct gate_vma;
-int vectors_user_mapping(void)
+static int __init gate_vma_init(void)
{
- struct mm_struct *mm = current->mm;
- return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
- VM_READ | VM_EXEC |
- VM_MAYREAD | VM_MAYEXEC |
- VM_ALWAYSDUMP | VM_RESERVED,
- NULL);
+ gate_vma.vm_start = 0xffff0000;
+ gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
+ gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
+ gate_vma.vm_flags = VM_READ | VM_EXEC |
+ VM_MAYREAD | VM_MAYEXEC |
+ VM_ALWAYSDUMP;
+ return 0;
+}
+arch_initcall(gate_vma_init);
+
+struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
+{
+ return &gate_vma;
+}
+
+int in_gate_area(struct mm_struct *mm, unsigned long addr)
+{
+ return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
+}
+
+int in_gate_area_no_mm(unsigned long addr)
+{
+ return in_gate_area(NULL, addr);
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
- return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
+ return (vma == &gate_vma) ? "[vectors]" : NULL;
}
#endif
--
1.7.4.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping
2012-01-17 16:50 [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping Will Deacon
@ 2012-01-17 19:11 ` Nicolas Pitre
2012-02-23 9:01 ` Russell King - ARM Linux
0 siblings, 1 reply; 4+ messages in thread
From: Nicolas Pitre @ 2012-01-17 19:11 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, 17 Jan 2012, Will Deacon wrote:
> The current user mapping for the vectors page is inserted as a `horrible
> hack vma' into each task via arch_setup_additional_pages. This causes
> problems with the MM subsystem and vm_normal_page, as described here:
>
> https://lkml.org/lkml/2012/1/14/55
>
> Following the suggestion from Hugh in the above thread, this patch uses
> the gate_vma for the vectors user mapping, therefore consolidating
> the horrible hack VMAs into one.
>
> Cc: Nicolas Pitre <nico@fluxnic.net>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Nicolas Pitre <nico@linaro.org>
> ---
>
> v2: Removed old arch_{exit,dup}_mmap implementations for ARM.
> Tested on vexpress (ctca9x4), PB1176 and AB926.
>
> arch/arm/include/asm/elf.h | 4 ---
> arch/arm/include/asm/mmu_context.h | 29 +--------------------------
> arch/arm/include/asm/page.h | 2 +
> arch/arm/kernel/process.c | 38 ++++++++++++++++++++++++++---------
> 4 files changed, 31 insertions(+), 42 deletions(-)
>
> diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
> index 0e9ce8d..38050b1 100644
> --- a/arch/arm/include/asm/elf.h
> +++ b/arch/arm/include/asm/elf.h
> @@ -130,8 +130,4 @@ struct mm_struct;
> extern unsigned long arch_randomize_brk(struct mm_struct *mm);
> #define arch_randomize_brk arch_randomize_brk
>
> -extern int vectors_user_mapping(void);
> -#define arch_setup_additional_pages(bprm, uses_interp) vectors_user_mapping()
> -#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
> -
> #endif
> diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> index 71605d9..a0b3cac 100644
> --- a/arch/arm/include/asm/mmu_context.h
> +++ b/arch/arm/include/asm/mmu_context.h
> @@ -18,6 +18,7 @@
> #include <asm/cacheflush.h>
> #include <asm/cachetype.h>
> #include <asm/proc-fns.h>
> +#include <asm-generic/mm_hooks.h>
>
> void __check_kvm_seq(struct mm_struct *mm);
>
> @@ -133,32 +134,4 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
> #define deactivate_mm(tsk,mm) do { } while (0)
> #define activate_mm(prev,next) switch_mm(prev, next, NULL)
>
> -/*
> - * We are inserting a "fake" vma for the user-accessible vector page so
> - * gdb and friends can get to it through ptrace and /proc/<pid>/mem.
> - * But we also want to remove it before the generic code gets to see it
> - * during process exit or the unmapping of it would cause total havoc.
> - * (the macro is used as remove_vma() is static to mm/mmap.c)
> - */
> -#define arch_exit_mmap(mm) \
> -do { \
> - struct vm_area_struct *high_vma = find_vma(mm, 0xffff0000); \
> - if (high_vma) { \
> - BUG_ON(high_vma->vm_next); /* it should be last */ \
> - if (high_vma->vm_prev) \
> - high_vma->vm_prev->vm_next = NULL; \
> - else \
> - mm->mmap = NULL; \
> - rb_erase(&high_vma->vm_rb, &mm->mm_rb); \
> - mm->mmap_cache = NULL; \
> - mm->map_count--; \
> - remove_vma(high_vma); \
> - } \
> -} while (0)
> -
> -static inline void arch_dup_mmap(struct mm_struct *oldmm,
> - struct mm_struct *mm)
> -{
> -}
> -
> #endif
> diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
> index 97b440c..5838361 100644
> --- a/arch/arm/include/asm/page.h
> +++ b/arch/arm/include/asm/page.h
> @@ -151,6 +151,8 @@ extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
> #define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
> extern void copy_page(void *to, const void *from);
>
> +#define __HAVE_ARCH_GATE_AREA 1
> +
> #ifdef CONFIG_ARM_LPAE
> #include <asm/pgtable-3level-types.h>
> #else
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index 971d65c..e11b523 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -526,22 +526,40 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
> #ifdef CONFIG_MMU
> /*
> * The vectors page is always readable from user space for the
> - * atomic helpers and the signal restart code. Let's declare a mapping
> - * for it so it is visible through ptrace and /proc/<pid>/mem.
> + * atomic helpers and the signal restart code. Insert it into the
> + * gate_vma so that it is visible through ptrace and /proc/<pid>/mem.
> */
> +static struct vm_area_struct gate_vma;
>
> -int vectors_user_mapping(void)
> +static int __init gate_vma_init(void)
> {
> - struct mm_struct *mm = current->mm;
> - return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
> - VM_READ | VM_EXEC |
> - VM_MAYREAD | VM_MAYEXEC |
> - VM_ALWAYSDUMP | VM_RESERVED,
> - NULL);
> + gate_vma.vm_start = 0xffff0000;
> + gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
> + gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
> + gate_vma.vm_flags = VM_READ | VM_EXEC |
> + VM_MAYREAD | VM_MAYEXEC |
> + VM_ALWAYSDUMP;
> + return 0;
> +}
> +arch_initcall(gate_vma_init);
> +
> +struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
> +{
> + return &gate_vma;
> +}
> +
> +int in_gate_area(struct mm_struct *mm, unsigned long addr)
> +{
> + return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
> +}
> +
> +int in_gate_area_no_mm(unsigned long addr)
> +{
> + return in_gate_area(NULL, addr);
> }
>
> const char *arch_vma_name(struct vm_area_struct *vma)
> {
> - return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
> + return (vma == &gate_vma) ? "[vectors]" : NULL;
> }
> #endif
> --
> 1.7.4.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping
2012-01-17 19:11 ` Nicolas Pitre
@ 2012-02-23 9:01 ` Russell King - ARM Linux
2012-02-23 9:57 ` Will Deacon
0 siblings, 1 reply; 4+ messages in thread
From: Russell King - ARM Linux @ 2012-02-23 9:01 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jan 17, 2012 at 02:11:14PM -0500, Nicolas Pitre wrote:
> On Tue, 17 Jan 2012, Will Deacon wrote:
>
> > The current user mapping for the vectors page is inserted as a `horrible
> > hack vma' into each task via arch_setup_additional_pages. This causes
> > problems with the MM subsystem and vm_normal_page, as described here:
> >
> > https://lkml.org/lkml/2012/1/14/55
> >
> > Following the suggestion from Hugh in the above thread, this patch uses
> > the gate_vma for the vectors user mapping, therefore consolidating
> > the horrible hack VMAs into one.
> >
> > Cc: Nicolas Pitre <nico@fluxnic.net>
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
>
> Acked-by: Nicolas Pitre <nico@linaro.org>
> Tested-by: Nicolas Pitre <nico@linaro.org>
Al Viro has spotted this patch, and commented on it last night:
| static struct vm_area_struct gate_vma;
| static int __init gate_vma_init(void)
| {
| gate_vma.vm_start = 0xffff0000;
| gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
| gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
| gate_vma.vm_flags = VM_READ | VM_EXEC |
| VM_MAYREAD | VM_MAYEXEC |
| VM_ALWAYSDUMP;
| return 0;
| }
| why bother with initcall?
| it's all constant, AFAICS
| IOW, why not initialize it statically and be done with that?
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping
2012-02-23 9:01 ` Russell King - ARM Linux
@ 2012-02-23 9:57 ` Will Deacon
0 siblings, 0 replies; 4+ messages in thread
From: Will Deacon @ 2012-02-23 9:57 UTC (permalink / raw)
To: linux-arm-kernel
Hi Russell,
On Thu, Feb 23, 2012 at 09:01:52AM +0000, Russell King - ARM Linux wrote:
> On Tue, Jan 17, 2012 at 02:11:14PM -0500, Nicolas Pitre wrote:
> > On Tue, 17 Jan 2012, Will Deacon wrote:
> >
> > > The current user mapping for the vectors page is inserted as a `horrible
> > > hack vma' into each task via arch_setup_additional_pages. This causes
> > > problems with the MM subsystem and vm_normal_page, as described here:
> > >
> > > https://lkml.org/lkml/2012/1/14/55
> > >
> > > Following the suggestion from Hugh in the above thread, this patch uses
> > > the gate_vma for the vectors user mapping, therefore consolidating
> > > the horrible hack VMAs into one.
> > >
> > > Cc: Nicolas Pitre <nico@fluxnic.net>
> > > Signed-off-by: Will Deacon <will.deacon@arm.com>
> >
> > Acked-by: Nicolas Pitre <nico@linaro.org>
> > Tested-by: Nicolas Pitre <nico@linaro.org>
>
> Al Viro has spotted this patch, and commented on it last night:
> | static struct vm_area_struct gate_vma;
> | static int __init gate_vma_init(void)
> | {
> | gate_vma.vm_start = 0xffff0000;
> | gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
> | gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
> | gate_vma.vm_flags = VM_READ | VM_EXEC |
> | VM_MAYREAD | VM_MAYEXEC |
> | VM_ALWAYSDUMP;
> | return 0;
> | }
> | why bother with initcall?
> | it's all constant, AFAICS
> | IOW, why not initialize it statically and be done with that?
PAGE_READONLY_EXEC isn't constant - it's constructed from pgprot_user which
is initialised in mmu.c during boot.
Will
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-01-17 16:50 [PATCH v2] ARM: vectors: use gate_vma for vectors user mapping Will Deacon
2012-01-17 19:11 ` Nicolas Pitre
2012-02-23 9:01 ` Russell King - ARM Linux
2012-02-23 9:57 ` Will Deacon
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