diff mbox series

[v3,6/8] linux: Add compatibility definitions to sys/prctl.h for MTE

Message ID 20201123154236.25809-7-rearnsha@arm.com
State Superseded
Headers show
Series Memory tagging support | expand

Commit Message

Richard Earnshaw Nov. 23, 2020, 3:42 p.m. UTC
Older versions of the Linux kernel headers obviously lack support for
memory tagging, but we still want to be able to build in support when
using those (obviously it can't be enabled on such systems).

The linux kernel extensions are made to the platform-independent
header (linux/prctl.h), so this patch takes a similar approach.
---
 sysdeps/unix/sysv/linux/sys/prctl.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Comments

Siddhesh Poyarekar Nov. 25, 2020, 3:26 p.m. UTC | #1
On 11/23/20 9:12 PM, Richard Earnshaw via Libc-alpha wrote:
> 
> Older versions of the Linux kernel headers obviously lack support for
> memory tagging, but we still want to be able to build in support when
> using those (obviously it can't be enabled on such systems).
> 
> The linux kernel extensions are made to the platform-independent
> header (linux/prctl.h), so this patch takes a similar approach.
> ---
>   sysdeps/unix/sysv/linux/sys/prctl.h | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 

The way x86_64 CET support does this is to add an architecture-specific 
prctl.h that includes the next prctl.h and adds its own definitions 
under it, thus keeping these changes separate.  It may be more 
consistent to stay with that approach within glibc.

Siddhesh
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/sys/prctl.h b/sysdeps/unix/sysv/linux/sys/prctl.h
index 7f748ebeeb..4d01379c23 100644
--- a/sysdeps/unix/sysv/linux/sys/prctl.h
+++ b/sysdeps/unix/sysv/linux/sys/prctl.h
@@ -21,6 +21,24 @@ 
 #include <features.h>
 #include <linux/prctl.h>  /*  The magic values come from here  */
 
+/* Recent extensions to linux which may post-date the kernel headers
+   we're picking up...  */
+
+/* Memory tagging control operations (for AArch64).  */
+#ifndef PR_TAGGED_ADDR_ENABLE
+# define PR_TAGGED_ADDR_ENABLE	(1UL << 8)
+#endif
+
+#ifndef PR_MTE_TCF_SHIFT
+# define PR_MTE_TCF_SHIFT	1
+# define PR_MTE_TCF_NONE	(0UL << PR_MTE_TCF_SHIFT)
+# define PR_MTE_TCF_SYNC	(1UL << PR_MTE_TCF_SHIFT)
+# define PR_MTE_TCF_ASYNC	(2UL << PR_MTE_TCF_SHIFT)
+# define PR_MTE_TCF_MASK	(3UL << PR_MTE_TCF_SHIFT)
+# define PR_MTE_TAG_SHIFT	3
+# define PR_MTE_TAG_MASK	(0xffffUL << PR_MTE_TAG_SHIFT)
+#endif
+
 __BEGIN_DECLS
 
 /* Control process execution.  */