[v5,2/6] vmalloc: Add text_alloc() and text_free()
diff mbox series

Message ID 20200724050553.1724168-3-jarkko.sakkinen@linux.intel.com
State New
Headers show
Series
  • arch/x86: kprobes: Remove MODULES dependency
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Commit Message

Jarkko Sakkinen July 24, 2020, 5:05 a.m. UTC
Introduce functions for allocating memory for dynamic trampolines, such
as kprobes. An arch can promote the availability of these functions with
CONFIG_ARCH_HAS_TEXT_ALLOC.

Cc: linux-mm@kvack.org
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 include/linux/vmalloc.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

Comments

Mike Rapoport July 24, 2020, 10:22 a.m. UTC | #1
On Fri, Jul 24, 2020 at 08:05:49AM +0300, Jarkko Sakkinen wrote:
> Introduce functions for allocating memory for dynamic trampolines, such
> as kprobes. An arch can promote the availability of these functions with
> CONFIG_ARCH_HAS_TEXT_ALLOC.

As it was pointed out at the discussion on the previous version [1],
text_alloc() alone won't necessarily suit other architectures.
 
I don't see a point in defining a "generic" interface that apriory could
not be imeplemented by several architectures.

[1] https://lore.kernel.org/lkml/20200714094625.1443261-1-jarkko.sakkinen@linux.intel.com/

> Cc: linux-mm@kvack.org
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  include/linux/vmalloc.h | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 0221f852a7e1..6c151a0ac02a 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -249,4 +249,21 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
>  int register_vmap_purge_notifier(struct notifier_block *nb);
>  int unregister_vmap_purge_notifier(struct notifier_block *nb);
>  
> +/*
> + * These functions can be optionally implemented by an arch in order to
> + * provide specialized functions for allocating trampoline code.
> + */
> +
> +#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
> +/*
> + * Allocate memory to be used for trampoline code.
> + */
> +void *text_alloc(unsigned long size);
> +
> +/*
> + * Free memory returned from text_alloc().
> + */
> +void text_free(void *region);
> +#endif /* CONFIG_ARCH_HAS_TEXT_ALLOC */
> +
>  #endif /* _LINUX_VMALLOC_H */
> -- 
> 2.25.1
>
Jarkko Sakkinen July 25, 2020, 2:20 a.m. UTC | #2
On Fri, Jul 24, 2020 at 01:22:43PM +0300, Mike Rapoport wrote:
> On Fri, Jul 24, 2020 at 08:05:49AM +0300, Jarkko Sakkinen wrote:
> > Introduce functions for allocating memory for dynamic trampolines, such
> > as kprobes. An arch can promote the availability of these functions with
> > CONFIG_ARCH_HAS_TEXT_ALLOC.
> 
> As it was pointed out at the discussion on the previous version [1],
> text_alloc() alone won't necessarily suit other architectures.
>  
> I don't see a point in defining a "generic" interface that apriory could
> not be imeplemented by several architectures.
> 
> [1] https://lore.kernel.org/lkml/20200714094625.1443261-1-jarkko.sakkinen@linux.intel.com/

These changes do actually acknowledge the feedback [1][2][3]. They do not
interfere with module_alloc() and are fully optional.

[1] https://lore.kernel.org/linux-riscv/20200714102826.GB4756@willie-the-truck/
[2] https://lore.kernel.org/linux-riscv/20200714164245.GE1551@shell.armlinux.org.uk/
[3] https://lore.kernel.org/linux-riscv/20200714135651.GA27819@linux-8ccs/

/Jarkko

Patch
diff mbox series

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 0221f852a7e1..6c151a0ac02a 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -249,4 +249,21 @@  pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
 int register_vmap_purge_notifier(struct notifier_block *nb);
 int unregister_vmap_purge_notifier(struct notifier_block *nb);
 
+/*
+ * These functions can be optionally implemented by an arch in order to
+ * provide specialized functions for allocating trampoline code.
+ */
+
+#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
+/*
+ * Allocate memory to be used for trampoline code.
+ */
+void *text_alloc(unsigned long size);
+
+/*
+ * Free memory returned from text_alloc().
+ */
+void text_free(void *region);
+#endif /* CONFIG_ARCH_HAS_TEXT_ALLOC */
+
 #endif /* _LINUX_VMALLOC_H */