Re: sys_times() return value
On Sat, Jul 23, 2005 at 03:35:31PM +1000, Andrew Morton wrote: > Russell King <[EMAIL PROTECTED]> wrote: > > ARM folk have recently pointed out a problem with sys_times(). > > When the kernel boots, we set jiffies to -5 minutes. This causes > > sys_times() to return a negative number, which increments through > > zero. > > > > However, some negative numbers are used to return error codes. > > Hence, there's a period of time when sys_times() returns values > > which are indistinguishable from error codes shortly after boot. > > What a strange system call. > > > This probably only affects 32-bit architectures. However, one > > wonders whether sys_times() needs force_successful_syscall_return(). > > I'd say so, yes. But lots of architectures seem to have a no-op there. As I mentioned below, these other architectures need glibc to be fixed. > > Also, it appears that glibc does indeed interpret the return value > > from sys_times in the way I describe above on at least ARM and x86. > > Other architectures may be similarly affected. Hopefully the ARM > > glibc folk will raise a cross-architecture bug in glibc for this. -- Russell King Linux kernel2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: sys_times() return value
On Sat, Jul 23, 2005 at 03:35:31PM +1000, Andrew Morton wrote: Russell King [EMAIL PROTECTED] wrote: ARM folk have recently pointed out a problem with sys_times(). When the kernel boots, we set jiffies to -5 minutes. This causes sys_times() to return a negative number, which increments through zero. However, some negative numbers are used to return error codes. Hence, there's a period of time when sys_times() returns values which are indistinguishable from error codes shortly after boot. What a strange system call. This probably only affects 32-bit architectures. However, one wonders whether sys_times() needs force_successful_syscall_return(). I'd say so, yes. But lots of architectures seem to have a no-op there. As I mentioned below, these other architectures need glibc to be fixed. Also, it appears that glibc does indeed interpret the return value from sys_times in the way I describe above on at least ARM and x86. Other architectures may be similarly affected. Hopefully the ARM glibc folk will raise a cross-architecture bug in glibc for this. -- Russell King Linux kernel2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: sys_times() return value
Russell King <[EMAIL PROTECTED]> wrote: > > Guys, > > ARM folk have recently pointed out a problem with sys_times(). > When the kernel boots, we set jiffies to -5 minutes. This causes > sys_times() to return a negative number, which increments through > zero. > > However, some negative numbers are used to return error codes. > Hence, there's a period of time when sys_times() returns values > which are indistinguishable from error codes shortly after boot. What a strange system call. > This probably only affects 32-bit architectures. However, one > wonders whether sys_times() needs force_successful_syscall_return(). I'd say so, yes. But lots of architectures seem to have a no-op there. > Also, it appears that glibc does indeed interpret the return value > from sys_times in the way I describe above on at least ARM and x86. > Other architectures may be similarly affected. Hopefully the ARM > glibc folk will raise a cross-architecture bug in glibc for this. > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: sys_times() return value
Russell King [EMAIL PROTECTED] wrote: Guys, ARM folk have recently pointed out a problem with sys_times(). When the kernel boots, we set jiffies to -5 minutes. This causes sys_times() to return a negative number, which increments through zero. However, some negative numbers are used to return error codes. Hence, there's a period of time when sys_times() returns values which are indistinguishable from error codes shortly after boot. What a strange system call. This probably only affects 32-bit architectures. However, one wonders whether sys_times() needs force_successful_syscall_return(). I'd say so, yes. But lots of architectures seem to have a no-op there. Also, it appears that glibc does indeed interpret the return value from sys_times in the way I describe above on at least ARM and x86. Other architectures may be similarly affected. Hopefully the ARM glibc folk will raise a cross-architecture bug in glibc for this. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
sys_times() return value
Guys, ARM folk have recently pointed out a problem with sys_times(). When the kernel boots, we set jiffies to -5 minutes. This causes sys_times() to return a negative number, which increments through zero. However, some negative numbers are used to return error codes. Hence, there's a period of time when sys_times() returns values which are indistinguishable from error codes shortly after boot. This probably only affects 32-bit architectures. However, one wonders whether sys_times() needs force_successful_syscall_return(). Also, it appears that glibc does indeed interpret the return value from sys_times in the way I describe above on at least ARM and x86. Other architectures may be similarly affected. Hopefully the ARM glibc folk will raise a cross-architecture bug in glibc for this. -- Russell King Linux kernel2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
sys_times() return value
Guys, ARM folk have recently pointed out a problem with sys_times(). When the kernel boots, we set jiffies to -5 minutes. This causes sys_times() to return a negative number, which increments through zero. However, some negative numbers are used to return error codes. Hence, there's a period of time when sys_times() returns values which are indistinguishable from error codes shortly after boot. This probably only affects 32-bit architectures. However, one wonders whether sys_times() needs force_successful_syscall_return(). Also, it appears that glibc does indeed interpret the return value from sys_times in the way I describe above on at least ARM and x86. Other architectures may be similarly affected. Hopefully the ARM glibc folk will raise a cross-architecture bug in glibc for this. -- Russell King Linux kernel2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
