Re: [PATCH 2/3] introduce probe_slab_address()
В Вт, 28/10/2014 в 21:12 +0100, Oleg Nesterov пишет:
> On 10/28, Oleg Nesterov wrote:
> >
> > On 10/28, Kirill Tkhai wrote:
> > >
> > > Yes, probe_kernel_read() is in [1/3], but it's not the same as
> > > __probe_kernel_read() for blackfin, for example.
> > >
> > > It's defined as
> > >
> > > long __weak probe_kernel_read(void *dst, const void *src, size_t size)
> > > __attribute__((alias("__probe_kernel_read")));
> > >
> > > But blackfin's probe_kernel_read() redefines this __weak function,
> > > isn't it? Didn't get_freepointer_safe() use to call architecture's
> > > probe_kernel_read() before?
> >
> > I _think_ that __probe_kernel_read(slab_ddr) should be fine.
> >
> > Yes, an architecture may want to reimplement probe_kernel_read() to
> > allow to safely access the special areas, or special addresses.
> >
> > But again, in this case we know that this address points to the
> > "normal" kernel memory, __copy_from_user_inatomic() should work fine.
>
> OTOH, perhaps probe_kernel_address() should use probe_kernel_read(), not
> __probe_kernel_read(). But currently it just calls __copy_inatomic() so
> 1/3 follows this logic.
Ok, thanks for the explanation, Oleg.
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Re: [PATCH 2/3] introduce probe_slab_address()
On 10/28, Oleg Nesterov wrote:
>
> On 10/28, Kirill Tkhai wrote:
> >
> > Yes, probe_kernel_read() is in [1/3], but it's not the same as
> > __probe_kernel_read() for blackfin, for example.
> >
> > It's defined as
> >
> > long __weak probe_kernel_read(void *dst, const void *src, size_t size)
> > __attribute__((alias("__probe_kernel_read")));
> >
> > But blackfin's probe_kernel_read() redefines this __weak function,
> > isn't it? Didn't get_freepointer_safe() use to call architecture's
> > probe_kernel_read() before?
>
> I _think_ that __probe_kernel_read(slab_ddr) should be fine.
>
> Yes, an architecture may want to reimplement probe_kernel_read() to
> allow to safely access the special areas, or special addresses.
>
> But again, in this case we know that this address points to the
> "normal" kernel memory, __copy_from_user_inatomic() should work fine.
OTOH, perhaps probe_kernel_address() should use probe_kernel_read(), not
__probe_kernel_read(). But currently it just calls __copy_inatomic() so
1/3 follows this logic.
Oleg.
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Re: [PATCH 2/3] introduce probe_slab_address()
On 10/28, Kirill Tkhai wrote:
>
> Yes, probe_kernel_read() is in [1/3], but it's not the same as
> __probe_kernel_read() for blackfin, for example.
>
> It's defined as
>
> long __weak probe_kernel_read(void *dst, const void *src, size_t size)
> __attribute__((alias("__probe_kernel_read")));
>
> But blackfin's probe_kernel_read() redefines this __weak function,
> isn't it? Didn't get_freepointer_safe() use to call architecture's
> probe_kernel_read() before?
I _think_ that __probe_kernel_read(slab_ddr) should be fine.
Yes, an architecture may want to reimplement probe_kernel_read() to
allow to safely access the special areas, or special addresses.
But again, in this case we know that this address points to the
"normal" kernel memory, __copy_from_user_inatomic() should work fine.
Oleg.
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Re: [PATCH 2/3] introduce probe_slab_address()
On 28.10.2014 20:56, Kirill Tkhai wrote:
> On 28.10.2014 18:01, Peter Zijlstra wrote:
>> On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote:
>>> В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
>>
+#define probe_slab_address(addr, retval) \
+ probe_kernel_address(addr, retval)
>>>
>>> probe_kernel_read() was arch-dependent on tree platforms:
>>>
>>> arch/blackfin/mm/maccess.c
>>> arch/parisc/lib/memcpy.c
>>> arch/um/kernel/maccess.c
>>>
>>> But now we skip these arch-dependent implementations. Is there no a problem?
>>
>> Nope, see the first patch, it makes probe_kernel_address use
>> __probe_kernel_read().
>>
>
> Yes, probe_kernel_read() is in [1/3], but it's not the same as
> __probe_kernel_read() for blackfin, for example.
Vise versa, I mean __probe_kernel_read() is in [1/3].
> It's defined as
>
> long __weak probe_kernel_read(void *dst, const void *src, size_t size)
> __attribute__((alias("__probe_kernel_read")));
>
> But blackfin's probe_kernel_read() redefines this __weak function,
> isn't it? Didn't get_freepointer_safe() use to call architecture's
> probe_kernel_read() before?
>
> I don't see how it is called now...
>
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Re: [PATCH 2/3] introduce probe_slab_address()
On 28.10.2014 18:01, Peter Zijlstra wrote:
> On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote:
>> В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
>
>>> +#define probe_slab_address(addr, retval) \
>>> + probe_kernel_address(addr, retval)
>>
>> probe_kernel_read() was arch-dependent on tree platforms:
>>
>> arch/blackfin/mm/maccess.c
>> arch/parisc/lib/memcpy.c
>> arch/um/kernel/maccess.c
>>
>> But now we skip these arch-dependent implementations. Is there no a problem?
>
> Nope, see the first patch, it makes probe_kernel_address use
> __probe_kernel_read().
>
Yes, probe_kernel_read() is in [1/3], but it's not the same as
__probe_kernel_read() for blackfin, for example.
It's defined as
long __weak probe_kernel_read(void *dst, const void *src, size_t size)
__attribute__((alias("__probe_kernel_read")));
But blackfin's probe_kernel_read() redefines this __weak function,
isn't it? Didn't get_freepointer_safe() use to call architecture's
probe_kernel_read() before?
I don't see how it is called now...
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Re: [PATCH 2/3] introduce probe_slab_address()
On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote: > В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет: > > +#define probe_slab_address(addr, retval) \ > > + probe_kernel_address(addr, retval) > > probe_kernel_read() was arch-dependent on tree platforms: > > arch/blackfin/mm/maccess.c > arch/parisc/lib/memcpy.c > arch/um/kernel/maccess.c > > But now we skip these arch-dependent implementations. Is there no a problem? Nope, see the first patch, it makes probe_kernel_address use __probe_kernel_read(). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote: В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет: +#define probe_slab_address(addr, retval) \ + probe_kernel_address(addr, retval) probe_kernel_read() was arch-dependent on tree platforms: arch/blackfin/mm/maccess.c arch/parisc/lib/memcpy.c arch/um/kernel/maccess.c But now we skip these arch-dependent implementations. Is there no a problem? Nope, see the first patch, it makes probe_kernel_address use __probe_kernel_read(). -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
On 28.10.2014 18:01, Peter Zijlstra wrote: On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote: В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет: +#define probe_slab_address(addr, retval) \ + probe_kernel_address(addr, retval) probe_kernel_read() was arch-dependent on tree platforms: arch/blackfin/mm/maccess.c arch/parisc/lib/memcpy.c arch/um/kernel/maccess.c But now we skip these arch-dependent implementations. Is there no a problem? Nope, see the first patch, it makes probe_kernel_address use __probe_kernel_read(). Yes, probe_kernel_read() is in [1/3], but it's not the same as __probe_kernel_read() for blackfin, for example. It's defined as long __weak probe_kernel_read(void *dst, const void *src, size_t size) __attribute__((alias(__probe_kernel_read))); But blackfin's probe_kernel_read() redefines this __weak function, isn't it? Didn't get_freepointer_safe() use to call architecture's probe_kernel_read() before? I don't see how it is called now... -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
On 28.10.2014 20:56, Kirill Tkhai wrote: On 28.10.2014 18:01, Peter Zijlstra wrote: On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote: В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет: +#define probe_slab_address(addr, retval) \ + probe_kernel_address(addr, retval) probe_kernel_read() was arch-dependent on tree platforms: arch/blackfin/mm/maccess.c arch/parisc/lib/memcpy.c arch/um/kernel/maccess.c But now we skip these arch-dependent implementations. Is there no a problem? Nope, see the first patch, it makes probe_kernel_address use __probe_kernel_read(). Yes, probe_kernel_read() is in [1/3], but it's not the same as __probe_kernel_read() for blackfin, for example. Vise versa, I mean __probe_kernel_read() is in [1/3]. It's defined as long __weak probe_kernel_read(void *dst, const void *src, size_t size) __attribute__((alias(__probe_kernel_read))); But blackfin's probe_kernel_read() redefines this __weak function, isn't it? Didn't get_freepointer_safe() use to call architecture's probe_kernel_read() before? I don't see how it is called now... -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
On 10/28, Kirill Tkhai wrote: Yes, probe_kernel_read() is in [1/3], but it's not the same as __probe_kernel_read() for blackfin, for example. It's defined as long __weak probe_kernel_read(void *dst, const void *src, size_t size) __attribute__((alias(__probe_kernel_read))); But blackfin's probe_kernel_read() redefines this __weak function, isn't it? Didn't get_freepointer_safe() use to call architecture's probe_kernel_read() before? I _think_ that __probe_kernel_read(slab_ddr) should be fine. Yes, an architecture may want to reimplement probe_kernel_read() to allow to safely access the special areas, or special addresses. But again, in this case we know that this address points to the normal kernel memory, __copy_from_user_inatomic() should work fine. Oleg. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
On 10/28, Oleg Nesterov wrote: On 10/28, Kirill Tkhai wrote: Yes, probe_kernel_read() is in [1/3], but it's not the same as __probe_kernel_read() for blackfin, for example. It's defined as long __weak probe_kernel_read(void *dst, const void *src, size_t size) __attribute__((alias(__probe_kernel_read))); But blackfin's probe_kernel_read() redefines this __weak function, isn't it? Didn't get_freepointer_safe() use to call architecture's probe_kernel_read() before? I _think_ that __probe_kernel_read(slab_ddr) should be fine. Yes, an architecture may want to reimplement probe_kernel_read() to allow to safely access the special areas, or special addresses. But again, in this case we know that this address points to the normal kernel memory, __copy_from_user_inatomic() should work fine. OTOH, perhaps probe_kernel_address() should use probe_kernel_read(), not __probe_kernel_read(). But currently it just calls __copy_inatomic() so 1/3 follows this logic. Oleg. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
В Вт, 28/10/2014 в 21:12 +0100, Oleg Nesterov пишет: On 10/28, Oleg Nesterov wrote: On 10/28, Kirill Tkhai wrote: Yes, probe_kernel_read() is in [1/3], but it's not the same as __probe_kernel_read() for blackfin, for example. It's defined as long __weak probe_kernel_read(void *dst, const void *src, size_t size) __attribute__((alias(__probe_kernel_read))); But blackfin's probe_kernel_read() redefines this __weak function, isn't it? Didn't get_freepointer_safe() use to call architecture's probe_kernel_read() before? I _think_ that __probe_kernel_read(slab_ddr) should be fine. Yes, an architecture may want to reimplement probe_kernel_read() to allow to safely access the special areas, or special addresses. But again, in this case we know that this address points to the normal kernel memory, __copy_from_user_inatomic() should work fine. OTOH, perhaps probe_kernel_address() should use probe_kernel_read(), not __probe_kernel_read(). But currently it just calls __copy_inatomic() so 1/3 follows this logic. Ok, thanks for the explanation, Oleg. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
В Вт, 28/10/2014 в 08:44 +0300, Kirill Tkhai пишет:
> В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
> > Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
> > into the new generic helper, probe_slab_address(). The next patch will add
> > another user.
> >
> > Signed-off-by: Oleg Nesterov
> > ---
> > include/linux/uaccess.h | 15 +++
> > mm/slub.c |6 +-
> > 2 files changed, 16 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> > index effb637..3367396 100644
> > --- a/include/linux/uaccess.h
> > +++ b/include/linux/uaccess.h
> > @@ -71,6 +71,21 @@ static inline unsigned long
> > __copy_from_user_nocache(void *to,
> > __probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval))
> >
> > /*
> > + * Same as probe_kernel_address(), but @addr must be the valid pointer
> > + * to a slab object, potentially freed/reused/unmapped.
> > + */
> > +#ifdef CONFIG_DEBUG_PAGEALLOC
> > +#define probe_slab_address(addr, retval) \
> > + probe_kernel_address(addr, retval)
> > +#else
> > +#define probe_slab_address(addr, retval) \
> > + ({ \
> > + (retval) = *(typeof(retval) *)(addr); \
> > + 0; \
> > + })
> > +#endif
> > +
> > +/*
> > * probe_kernel_read(): safely attempt to read from a location
> > * @dst: pointer to the buffer that shall take the data
> > * @src: address to read from
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 3e8afcc..0467d22 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct
> > kmem_cache *s, void *object)
> > {
> > void *p;
> >
> > -#ifdef CONFIG_DEBUG_PAGEALLOC
> > - probe_kernel_read(, (void **)(object + s->offset), sizeof(p));
> > -#else
> > - p = get_freepointer(s, object);
> > -#endif
> > + probe_slab_address(object + s->offset, p);
> > return p;
> > }
> >
>
> probe_kernel_read() was arch-dependent on tree platforms:
Of course, I mean get_freepointer_safe() used to use arch-dependent
probe_kernel_read() on blackfin, parisc and um.
> arch/blackfin/mm/maccess.c
> arch/parisc/lib/memcpy.c
> arch/um/kernel/maccess.c
>
> But now we skip these arch-dependent implementations. Is there no a problem?
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Re: [PATCH 2/3] introduce probe_slab_address()
В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
> Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
> into the new generic helper, probe_slab_address(). The next patch will add
> another user.
>
> Signed-off-by: Oleg Nesterov
> ---
> include/linux/uaccess.h | 15 +++
> mm/slub.c |6 +-
> 2 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index effb637..3367396 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void
> *to,
> __probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval))
>
> /*
> + * Same as probe_kernel_address(), but @addr must be the valid pointer
> + * to a slab object, potentially freed/reused/unmapped.
> + */
> +#ifdef CONFIG_DEBUG_PAGEALLOC
> +#define probe_slab_address(addr, retval) \
> + probe_kernel_address(addr, retval)
> +#else
> +#define probe_slab_address(addr, retval) \
> + ({ \
> + (retval) = *(typeof(retval) *)(addr); \
> + 0; \
> + })
> +#endif
> +
> +/*
> * probe_kernel_read(): safely attempt to read from a location
> * @dst: pointer to the buffer that shall take the data
> * @src: address to read from
> diff --git a/mm/slub.c b/mm/slub.c
> index 3e8afcc..0467d22 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct
> kmem_cache *s, void *object)
> {
> void *p;
>
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> - probe_kernel_read(, (void **)(object + s->offset), sizeof(p));
> -#else
> - p = get_freepointer(s, object);
> -#endif
> + probe_slab_address(object + s->offset, p);
> return p;
> }
>
probe_kernel_read() was arch-dependent on tree platforms:
arch/blackfin/mm/maccess.c
arch/parisc/lib/memcpy.c
arch/um/kernel/maccess.c
But now we skip these arch-dependent implementations. Is there no a problem?
Kirill
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Re: [PATCH 2/3] introduce probe_slab_address()
On Mon, 27 Oct 2014, Oleg Nesterov wrote: > Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe() > into the new generic helper, probe_slab_address(). The next patch will add > another user. Acked-by: Christoph Lameter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/3] introduce probe_slab_address()
Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
into the new generic helper, probe_slab_address(). The next patch will add
another user.
Signed-off-by: Oleg Nesterov
---
include/linux/uaccess.h | 15 +++
mm/slub.c |6 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index effb637..3367396 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void
*to,
__probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval))
/*
+ * Same as probe_kernel_address(), but @addr must be the valid pointer
+ * to a slab object, potentially freed/reused/unmapped.
+ */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+#define probe_slab_address(addr, retval) \
+ probe_kernel_address(addr, retval)
+#else
+#define probe_slab_address(addr, retval) \
+ ({ \
+ (retval) = *(typeof(retval) *)(addr); \
+ 0; \
+ })
+#endif
+
+/*
* probe_kernel_read(): safely attempt to read from a location
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc..0467d22 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct kmem_cache
*s, void *object)
{
void *p;
-#ifdef CONFIG_DEBUG_PAGEALLOC
- probe_kernel_read(, (void **)(object + s->offset), sizeof(p));
-#else
- p = get_freepointer(s, object);
-#endif
+ probe_slab_address(object + s->offset, p);
return p;
}
--
1.5.5.1
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[PATCH 2/3] introduce probe_slab_address()
Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
into the new generic helper, probe_slab_address(). The next patch will add
another user.
Signed-off-by: Oleg Nesterov o...@redhat.com
---
include/linux/uaccess.h | 15 +++
mm/slub.c |6 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index effb637..3367396 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void
*to,
__probe_kernel_read((retval), (__force void *)(addr), sizeof(retval))
/*
+ * Same as probe_kernel_address(), but @addr must be the valid pointer
+ * to a slab object, potentially freed/reused/unmapped.
+ */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+#define probe_slab_address(addr, retval) \
+ probe_kernel_address(addr, retval)
+#else
+#define probe_slab_address(addr, retval) \
+ ({ \
+ (retval) = *(typeof(retval) *)(addr); \
+ 0; \
+ })
+#endif
+
+/*
* probe_kernel_read(): safely attempt to read from a location
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc..0467d22 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct kmem_cache
*s, void *object)
{
void *p;
-#ifdef CONFIG_DEBUG_PAGEALLOC
- probe_kernel_read(p, (void **)(object + s-offset), sizeof(p));
-#else
- p = get_freepointer(s, object);
-#endif
+ probe_slab_address(object + s-offset, p);
return p;
}
--
1.5.5.1
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Re: [PATCH 2/3] introduce probe_slab_address()
On Mon, 27 Oct 2014, Oleg Nesterov wrote: Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe() into the new generic helper, probe_slab_address(). The next patch will add another user. Acked-by: Christoph Lameter c...@linux.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/3] introduce probe_slab_address()
В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
into the new generic helper, probe_slab_address(). The next patch will add
another user.
Signed-off-by: Oleg Nesterov o...@redhat.com
---
include/linux/uaccess.h | 15 +++
mm/slub.c |6 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index effb637..3367396 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void
*to,
__probe_kernel_read((retval), (__force void *)(addr), sizeof(retval))
/*
+ * Same as probe_kernel_address(), but @addr must be the valid pointer
+ * to a slab object, potentially freed/reused/unmapped.
+ */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+#define probe_slab_address(addr, retval) \
+ probe_kernel_address(addr, retval)
+#else
+#define probe_slab_address(addr, retval) \
+ ({ \
+ (retval) = *(typeof(retval) *)(addr); \
+ 0; \
+ })
+#endif
+
+/*
* probe_kernel_read(): safely attempt to read from a location
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc..0467d22 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct
kmem_cache *s, void *object)
{
void *p;
-#ifdef CONFIG_DEBUG_PAGEALLOC
- probe_kernel_read(p, (void **)(object + s-offset), sizeof(p));
-#else
- p = get_freepointer(s, object);
-#endif
+ probe_slab_address(object + s-offset, p);
return p;
}
probe_kernel_read() was arch-dependent on tree platforms:
arch/blackfin/mm/maccess.c
arch/parisc/lib/memcpy.c
arch/um/kernel/maccess.c
But now we skip these arch-dependent implementations. Is there no a problem?
Kirill
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Re: [PATCH 2/3] introduce probe_slab_address()
В Вт, 28/10/2014 в 08:44 +0300, Kirill Tkhai пишет:
В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe()
into the new generic helper, probe_slab_address(). The next patch will add
another user.
Signed-off-by: Oleg Nesterov o...@redhat.com
---
include/linux/uaccess.h | 15 +++
mm/slub.c |6 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index effb637..3367396 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -71,6 +71,21 @@ static inline unsigned long
__copy_from_user_nocache(void *to,
__probe_kernel_read((retval), (__force void *)(addr), sizeof(retval))
/*
+ * Same as probe_kernel_address(), but @addr must be the valid pointer
+ * to a slab object, potentially freed/reused/unmapped.
+ */
+#ifdef CONFIG_DEBUG_PAGEALLOC
+#define probe_slab_address(addr, retval) \
+ probe_kernel_address(addr, retval)
+#else
+#define probe_slab_address(addr, retval) \
+ ({ \
+ (retval) = *(typeof(retval) *)(addr); \
+ 0; \
+ })
+#endif
+
+/*
* probe_kernel_read(): safely attempt to read from a location
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc..0467d22 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct
kmem_cache *s, void *object)
{
void *p;
-#ifdef CONFIG_DEBUG_PAGEALLOC
- probe_kernel_read(p, (void **)(object + s-offset), sizeof(p));
-#else
- p = get_freepointer(s, object);
-#endif
+ probe_slab_address(object + s-offset, p);
return p;
}
probe_kernel_read() was arch-dependent on tree platforms:
Of course, I mean get_freepointer_safe() used to use arch-dependent
probe_kernel_read() on blackfin, parisc and um.
arch/blackfin/mm/maccess.c
arch/parisc/lib/memcpy.c
arch/um/kernel/maccess.c
But now we skip these arch-dependent implementations. Is there no a problem?
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