On 05/23/2011 08:50 PM, H. Peter Anvin wrote: I actually have a followup patch which does this, but which simultaneously fixes all arches. It's bigger than this specific problem though. I guess we can see this as 2 problems. 1) The audit_syscall_exit function expects a long. But if you chop off the upper 32 bits you can't tell positive from negative. Thus when it prints to userspace using %ld we have a problem: Aka printf("%ld", (long)(u32)(-13)) = "4294967283" vs printf("%ld", (long)(-13)) = "-13" 2) The current code uses pos/neg to determine 'success' on many arches. It should use >= -MAX_ERRNO I had patches briefly which truncated rax to 32 bits. Checked if it was an errno, then if so, sign extended it back to 64 bits for the call to audit_syscall_exit. Although that logically made sense it wasted instructions doing truncation of rax->eax and then sometimes expansion back when rax had the right upper 32 bits all along. diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index b2bea0a..d9170de 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -14,6 +14,7 @@ #include <asm/segment.h> #include <asm/irqflags.h> #include <linux/linkage.h> +#include <linux/err.h> /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ #include <linux/elf-em.h> @@ -210,11 +211,10 @@ sysexit_from_sys_call: TRACE_IRQS_ON sti movq %rax,%rsi /* second arg, syscall return value */ - cmpq $0,%rax /* is it < 0? */ + cmpq $-MAX_ERRNO,%rax /* is it < 0? */