From: Al Viro viro@zeniv.linux.org.uk
commit fd0c153daad135d0ec1a53c5dbe6936a724d6ae1 upstream.
If we use the ancient SysV syscall ABI, we'd better have tell the kernel how to claim that a negative return value is a success. Use ->orig_r2 for that - it's inaccessible via ptrace, so it's a fair game for changes and it's normally[*] non-negative on return from syscall. Set to -1; syscall is not going to be restart-worthy by definition, so we won't interfere with that use either.
[*] the only exception is rt_sigreturn(), where we skip the entire messing with r1/r2 anyway.
Fixes: 82ed08dd1b0e ("nios2: Exception handling") Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Dinh Nguyen dinguyen@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/nios2/include/asm/ptrace.h | 2 ++ arch/nios2/kernel/entry.S | 6 ++++++ 2 files changed, 8 insertions(+)
--- a/arch/nios2/include/asm/ptrace.h +++ b/arch/nios2/include/asm/ptrace.h @@ -74,6 +74,8 @@ extern void show_regs(struct pt_regs *); ((struct pt_regs *)((unsigned long)current_thread_info() + THREAD_SIZE)\ - 1)
+#define force_successful_syscall_return() (current_pt_regs()->orig_r2 = -1) + int do_syscall_trace_enter(void); void do_syscall_trace_exit(void); #endif /* __ASSEMBLY__ */ --- a/arch/nios2/kernel/entry.S +++ b/arch/nios2/kernel/entry.S @@ -213,6 +213,9 @@ local_restart: translate_rc_and_ret: movi r1, 0 bge r2, zero, 3f + ldw r1, PT_ORIG_R2(sp) + addi r1, r1, 1 + beq r1, zero, 3f sub r2, zero, r2 movi r1, 1 3: @@ -276,6 +279,9 @@ traced_system_call: translate_rc_and_ret2: movi r1, 0 bge r2, zero, 4f + ldw r1, PT_ORIG_R2(sp) + addi r1, r1, 1 + beq r1, zero, 4f sub r2, zero, r2 movi r1, 1 4: