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Subject[RFC][PATCH 1/3] powerpc: Don't force ENOSYS as error on syscall fail
Date
In certain scenarios - e.g. seccomp filtering with ERRNO as default action -
the system call fails for other reasons than the syscall not being available.
The seccomp filter can be configured to store a user-defined error code on
return from a blacklisted syscall.

The RFC is this: are there currently any user-space scenarios where it is
required that the system call return ENOSYS as error code on failure, no matter
the circumstances? I don't want to break userspace requirements. I have not
added code to force this error code in situations different than
secure_computing failure, in order to keep overhead at a minimum.

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com>
---
arch/powerpc/kernel/entry_32.S | 3 ++-
arch/powerpc/kernel/entry_64.S | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 59848e5..52e48dd 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -425,7 +425,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
b 1b
#endif /* CONFIG_44x */

-66: li r3,-ENOSYS
+66:
+# li r3,-ENOSYS
b ret_from_syscall

.globl ret_from_fork
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e6bfe8e..80db02e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -269,7 +269,7 @@ syscall_dotrace:
b .Lsyscall_dotrace_cont

syscall_enosys:
- li r3,-ENOSYS
+# li r3,-ENOSYS
b syscall_exit

syscall_exit_work:
--
2.1.4


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