signal/mips: Document a conflict with SI_USER with SIGFPE (ea1b75cf) · Commits · 戴 / test

Setting si_code to __SI_FAULT results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. This use of of __SI_FAULT is only a decade old. Which compared to the other pieces of kernel code that has made this mistake is almost yesterday. This is probably worth fixing but I don't know mips well enough to know what si_code to would be the proper one to use. Cc: Ralf Baechle <ralf@linux-mips.org> Ref: ("[MIPS] Maintain si_code field properly for FP exceptions") Signed-off-by:

"Eric W. Biederman" <ebiederm@xmission.com>

arch/mips/include/uapi/asm/siginfo.h

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -123,4 +123,11 @@ typedef struct siginfo {
	#define SI_TIMER __SI_CODE(__SI_TIMER, -3) /* sent by timer expiration */		#define SI_TIMER __SI_CODE(__SI_TIMER, -3) /* sent by timer expiration */
	#define SI_MESGQ __SI_CODE(__SI_MESGQ, -4) /* sent by real time mesq state change */		#define SI_MESGQ __SI_CODE(__SI_MESGQ, -4) /* sent by real time mesq state change */

			/*
			* SIGFPE si_codes
			*/
			#ifdef __KERNEL__
			#define FPE_FIXME (__SI_FAULT\|0) /* Broken dup of SI_USER */
			#endif /* __KERNEL__ */

	#endif /* _UAPI_ASM_SIGINFO_H */		#endif /* _UAPI_ASM_SIGINFO_H */

arch/mips/kernel/traps.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -735,7 +735,7 @@ void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr,
	else if (fcr31 & FPU_CSR_INE_X)		else if (fcr31 & FPU_CSR_INE_X)
	si.si_code = FPE_FLTRES;		si.si_code = FPE_FLTRES;
	else		else
	si.si_code = __SI_FAULT;		si.si_code = FPE_FIXME;
	force_sig_info(SIGFPE, &si, tsk);		force_sig_info(SIGFPE, &si, tsk);
	}		}

Admin message