Re: [RFC] making HAVE_SYSCALL_WRAPPERS universal (Re: Issues with"x86, um: switch to generic fork/vfork/clone" commit)

[James Hogan]

On 21/01/13 22:55, Al Viro wrote:
> I've tried to sanitize cond_syscall/SYSCALL_ALIAS situation; the tree is in
> git.kernel.org/pub/scm/linux/kernel/git/viro/signal experimental-syscalls
> NOTE: this is absolutely untested and might very well blow up
> on any number of architectures.
> 
> Review and comments would be very welcome.

Looking at "consolidate cond_syscall and SYSCALL_ALIAS declarations",
is it worth having the default __SYMBOL_NAME declaration in
include/linux/linkage.h make use of CONFIG_SYMBOL_PREFIX?

E.g. in the metag patchset we currently have the patch below.

Admittedly CONFIG_SYMBOL_PREFIX is a string which would make it's use in
SYMBOL_NAME a bit awkward.

Cheers
James


Subject: [PATCH v3 02/44] asm-generic/unistd.h: handle symbol prefixes in
 cond_syscall

Some architectures have symbol prefixes and set CONFIG_SYMBOL_PREFIX,
but this wasn't taken into account by the generic cond_syscall. It's
easy enough to fix in a generic fashion, so add the symbol prefix to
symbol names in cond_syscall when CONFIG_SYMBOL_PREFIX is set.

Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Mike Frysinger <vapier@xxxxxxxxxx>
---
 include/asm-generic/unistd.h |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/include/asm-generic/unistd.h b/include/asm-generic/unistd.h
index 257c55e..4077b5d 100644
--- a/include/asm-generic/unistd.h
+++ b/include/asm-generic/unistd.h
@@ -17,5 +17,12 @@
  * but it doesn't work on all toolchains, so we just do it by hand
  */
 #ifndef cond_syscall
-#define cond_syscall(x) asm(".weak\t" #x "\n\t.set\t" #x ",sys_ni_syscall")
+#ifdef CONFIG_SYMBOL_PREFIX
+#define __SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
+#else
+#define __SYMBOL_PREFIX
+#endif
+#define cond_syscall(x) asm(".weak\t" __SYMBOL_PREFIX #x "\n\t" \
+			    ".set\t" __SYMBOL_PREFIX #x "," \
+			    __SYMBOL_PREFIX "sys_ni_syscall")
 #endif
-- 
1.7.7.6

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