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Subject: Re: [REVIEW][PATCH 13/22] signal/parisc: Use force_sig_fault where
 appropriate
To:     "Eric W. Biederman" <ebiederm@xmission.com>,
        linux-arch@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        James Bottomley <jejb@parisc-linux.org>,
        linux-parisc@vger.kernel.org
References: <87604mhrnb.fsf@xmission.com>
 <20180420143811.9994-13-ebiederm@xmission.com>
From:   Helge Deller <deller@gmx.de>
Message-ID: <0c19d397-57d2-9b39-19f3-f989b34e1580@gmx.de>
Date:   Sat, 21 Apr 2018 19:24:06 +0200
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On 20.04.2018 16:38, Eric W. Biederman wrote:
> Filling in struct siginfo before calling force_sig_info a tedious and
> error prone process, where once in a great while the wrong fields
> are filled out, and siginfo has been inconsistently cleared.
> 
> Simplify this process by using the helper force_sig_fault.  Which
> takes as a parameters all of the information it needs, ensures
> all of the fiddly bits of filling in struct siginfo are done properly
> and then calls force_sig_info.
> 
> In short about a 5 line reduction in code for every time force_sig_info
> is called, which makes the calling function clearer.
> 
> Cc: James Bottomley <jejb@parisc-linux.org>
> Cc: Helge Deller <deller@gmx.de>
> Cc: linux-parisc@vger.kernel.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

I pulled this whole patch series from your git tree and 
booted it on 32- and 64-bit parisc kernels.
 
Acked-by: Helge Deller <deller@gmx.de>   # parisc

Thanks!
Helge

> ---
>  arch/parisc/kernel/ptrace.c    | 11 ++------
>  arch/parisc/kernel/traps.c     | 63 ++++++++++++++----------------------------
>  arch/parisc/kernel/unaligned.c | 16 +++--------
>  arch/parisc/math-emu/driver.c  |  9 ++----
>  arch/parisc/mm/fault.c         | 25 +++++++----------
>  5 files changed, 39 insertions(+), 85 deletions(-)
> 
> diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
> index b1c12ceb1c88..7aa1d4d0d444 100644
> --- a/arch/parisc/kernel/ptrace.c
> +++ b/arch/parisc/kernel/ptrace.c
> @@ -76,8 +76,6 @@ void user_enable_single_step(struct task_struct *task)
>  	set_tsk_thread_flag(task, TIF_SINGLESTEP);
>  
>  	if (pa_psw(task)->n) {
> -		struct siginfo si;
> -
>  		/* Nullified, just crank over the queue. */
>  		task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
>  		task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
> @@ -90,12 +88,9 @@ void user_enable_single_step(struct task_struct *task)
>  		ptrace_disable(task);
>  		/* Don't wake up the task, but let the
>  		   parent know something happened. */
> -		clear_siginfo(&si);
> -		si.si_code = TRAP_TRACE;
> -		si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
> -		si.si_signo = SIGTRAP;
> -		si.si_errno = 0;
> -		force_sig_info(SIGTRAP, &si, task);
> +		force_sig_fault(SIGTRAP, TRAP_TRACE,
> +				(void __user *) (task_regs(task)->iaoq[0] & ~3),
> +				task);
>  		/* notify_parent(task, SIGCHLD); */
>  		return;
>  	}
> diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
> index 98f9f2f85940..132b09c657ff 100644
> --- a/arch/parisc/kernel/traps.c
> +++ b/arch/parisc/kernel/traps.c
> @@ -297,14 +297,8 @@ void die_if_kernel(char *str, struct pt_regs *regs, long err)
>  #define GDB_BREAK_INSN 0x10004
>  static void handle_gdb_break(struct pt_regs *regs, int wot)
>  {
> -	struct siginfo si;
> -
> -	clear_siginfo(&si);
> -	si.si_signo = SIGTRAP;
> -	si.si_errno = 0;
> -	si.si_code = wot;
> -	si.si_addr = (void __user *) (regs->iaoq[0] & ~3);
> -	force_sig_info(SIGTRAP, &si, current);
> +	force_sig_fault(SIGTRAP, wot,
> +			(void __user *) (regs->iaoq[0] & ~3), current);
>  }
>  
>  static void handle_break(struct pt_regs *regs)
> @@ -488,9 +482,8 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  {
>  	unsigned long fault_address = 0;
>  	unsigned long fault_space = 0;
> -	struct siginfo si;
> +	int si_code;
>  
> -	clear_siginfo(&si);
>  	if (code == 1)
>  	    pdc_console_restart();  /* switch back to pdc if HPMC */
>  	else
> @@ -573,7 +566,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  	case  8:
>  		/* Illegal instruction trap */
>  		die_if_kernel("Illegal instruction", regs, code);
> -		si.si_code = ILL_ILLOPC;
> +		si_code = ILL_ILLOPC;
>  		goto give_sigill;
>  
>  	case  9:
> @@ -584,7 +577,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  	case 10:
>  		/* Privileged operation trap */
>  		die_if_kernel("Privileged operation", regs, code);
> -		si.si_code = ILL_PRVOPC;
> +		si_code = ILL_PRVOPC;
>  		goto give_sigill;
>  
>  	case 11:
> @@ -607,20 +600,16 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  		}
>  
>  		die_if_kernel("Privileged register usage", regs, code);
> -		si.si_code = ILL_PRVREG;
> +		si_code = ILL_PRVREG;
>  	give_sigill:
> -		si.si_signo = SIGILL;
> -		si.si_errno = 0;
> -		si.si_addr = (void __user *) regs->iaoq[0];
> -		force_sig_info(SIGILL, &si, current);
> +		force_sig_fault(SIGILL, si_code,
> +				(void __user *) regs->iaoq[0], current);
>  		return;
>  
>  	case 12:
>  		/* Overflow Trap, let the userland signal handler do the cleanup */
> -		si.si_signo = SIGFPE;
> -		si.si_code = FPE_INTOVF;
> -		si.si_addr = (void __user *) regs->iaoq[0];
> -		force_sig_info(SIGFPE, &si, current);
> +		force_sig_fault(SIGFPE, FPE_INTOVF,
> +				(void __user *) regs->iaoq[0], current);
>  		return;
>  		
>  	case 13:
> @@ -628,13 +617,11 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  		   The condition succeeds in an instruction which traps
>  		   on condition  */
>  		if(user_mode(regs)){
> -			si.si_signo = SIGFPE;
>  			/* Let userspace app figure it out from the insn pointed
>  			 * to by si_addr.
>  			 */
> -			si.si_code = FPE_CONDTRAP;
> -			si.si_addr = (void __user *) regs->iaoq[0];
> -			force_sig_info(SIGFPE, &si, current);
> +			force_sig_fault(SIGFPE, FPE_CONDTRAP,
> +					(void __user *) regs->iaoq[0], current);
>  			return;
>  		} 
>  		/* The kernel doesn't want to handle condition codes */
> @@ -743,14 +730,10 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  			return;
>  
>  		die_if_kernel("Protection id trap", regs, code);
> -		si.si_code = SEGV_MAPERR;
> -		si.si_signo = SIGSEGV;
> -		si.si_errno = 0;
> -		if (code == 7)
> -		    si.si_addr = (void __user *) regs->iaoq[0];
> -		else
> -		    si.si_addr = (void __user *) regs->ior;
> -		force_sig_info(SIGSEGV, &si, current);
> +		force_sig_fault(SIGSEGV, SEGV_MAPERR,
> +				(code == 7)?
> +				((void __user *) regs->iaoq[0]) :
> +				((void __user *) regs->ior), current);
>  		return;
>  
>  	case 28: 
> @@ -764,11 +747,8 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  				"handle_interruption() pid=%d command='%s'\n",
>  				task_pid_nr(current), current->comm);
>  			/* SIGBUS, for lack of a better one. */
> -			si.si_signo = SIGBUS;
> -			si.si_code = BUS_OBJERR;
> -			si.si_errno = 0;
> -			si.si_addr = (void __user *) regs->ior;
> -			force_sig_info(SIGBUS, &si, current);
> +			force_sig_fault(SIGBUS, BUS_OBJERR,
> +					(void __user *)regs->ior, current);
>  			return;
>  		}
>  		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
> @@ -783,11 +763,8 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
>  				"User fault %d on space 0x%08lx, pid=%d command='%s'\n",
>  				code, fault_space,
>  				task_pid_nr(current), current->comm);
> -		si.si_signo = SIGSEGV;
> -		si.si_errno = 0;
> -		si.si_code = SEGV_MAPERR;
> -		si.si_addr = (void __user *) regs->ior;
> -		force_sig_info(SIGSEGV, &si, current);
> +		force_sig_fault(SIGSEGV, SEGV_MAPERR,
> +				(void __user *)regs->ior, current);
>  		return;
>  	    }
>  	}
> diff --git a/arch/parisc/kernel/unaligned.c b/arch/parisc/kernel/unaligned.c
> index 30b7c7f6c471..932bfc0b7cd8 100644
> --- a/arch/parisc/kernel/unaligned.c
> +++ b/arch/parisc/kernel/unaligned.c
> @@ -452,10 +452,8 @@ void handle_unaligned(struct pt_regs *regs)
>  	unsigned long newbase = R1(regs->iir)?regs->gr[R1(regs->iir)]:0;
>  	int modify = 0;
>  	int ret = ERR_NOTHANDLED;
> -	struct siginfo si;
>  	register int flop=0;	/* true if this is a flop */
>  
> -	clear_siginfo(&si);
>  	__inc_irq_stat(irq_unaligned_count);
>  
>  	/* log a message with pacing */
> @@ -691,21 +689,15 @@ void handle_unaligned(struct pt_regs *regs)
>  
>  		if (ret == ERR_PAGEFAULT)
>  		{
> -			si.si_signo = SIGSEGV;
> -			si.si_errno = 0;
> -			si.si_code = SEGV_MAPERR;
> -			si.si_addr = (void __user *)regs->ior;
> -			force_sig_info(SIGSEGV, &si, current);
> +			force_sig_fault(SIGSEGV, SEGV_MAPERR,
> +					(void __user *)regs->ior, current);
>  		}
>  		else
>  		{
>  force_sigbus:
>  			/* couldn't handle it ... */
> -			si.si_signo = SIGBUS;
> -			si.si_errno = 0;
> -			si.si_code = BUS_ADRALN;
> -			si.si_addr = (void __user *)regs->ior;
> -			force_sig_info(SIGBUS, &si, current);
> +			force_sig_fault(SIGBUS, BUS_ADRALN,
> +					(void __user *)regs->ior, current);
>  		}
>  		
>  		return;
> diff --git a/arch/parisc/math-emu/driver.c b/arch/parisc/math-emu/driver.c
> index 0d10efb53361..0590e05571d1 100644
> --- a/arch/parisc/math-emu/driver.c
> +++ b/arch/parisc/math-emu/driver.c
> @@ -81,7 +81,6 @@ int
>  handle_fpe(struct pt_regs *regs)
>  {
>  	extern void printbinary(unsigned long x, int nbits);
> -	struct siginfo si;
>  	unsigned int orig_sw, sw;
>  	int signalcode;
>  	/* need an intermediate copy of float regs because FPU emulation
> @@ -93,7 +92,6 @@ handle_fpe(struct pt_regs *regs)
>  	 */
>  	__u64 frcopy[36];
>  
> -	clear_siginfo(&si);
>  	memcpy(frcopy, regs->fr, sizeof regs->fr);
>  	frcopy[32] = 0;
>  
> @@ -118,11 +116,8 @@ handle_fpe(struct pt_regs *regs)
>  
>  	memcpy(regs->fr, frcopy, sizeof regs->fr);
>  	if (signalcode != 0) {
> -	    si.si_signo = signalcode >> 24;
> -	    si.si_errno = 0;
> -	    si.si_code = signalcode & 0xffffff;
> -	    si.si_addr = (void __user *) regs->iaoq[0];
> -	    force_sig_info(si.si_signo, &si, current);
> +	    force_sig_fault(signalcode >> 24, signalcode & 0xffffff,
> +			    (void __user *) regs->iaoq[0], current);
>  	    return -1;
>  	}
>  
> diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
> index 51215b0048ef..a80117980fc2 100644
> --- a/arch/parisc/mm/fault.c
> +++ b/arch/parisc/mm/fault.c
> @@ -353,23 +353,22 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
>  	up_read(&mm->mmap_sem);
>  
>  	if (user_mode(regs)) {
> -		struct siginfo si;
> +		int signo, si_code;
>  
> -		clear_siginfo(&si);
>  		switch (code) {
>  		case 15:	/* Data TLB miss fault/Data page fault */
>  			/* send SIGSEGV when outside of vma */
>  			if (!vma ||
>  			    address < vma->vm_start || address >= vma->vm_end) {
> -				si.si_signo = SIGSEGV;
> -				si.si_code = SEGV_MAPERR;
> +				signo = SIGSEGV;
> +				si_code = SEGV_MAPERR;
>  				break;
>  			}
>  
>  			/* send SIGSEGV for wrong permissions */
>  			if ((vma->vm_flags & acc_type) != acc_type) {
> -				si.si_signo = SIGSEGV;
> -				si.si_code = SEGV_ACCERR;
> +				signo = SIGSEGV;
> +				si_code = SEGV_ACCERR;
>  				break;
>  			}
>  
> @@ -377,17 +376,16 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
>  			/* fall through */
>  		case 17:	/* NA data TLB miss / page fault */
>  		case 18:	/* Unaligned access - PCXS only */
> -			si.si_signo = SIGBUS;
> -			si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
> +			signo = SIGBUS;
> +			si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
>  			break;
>  		case 16:	/* Non-access instruction TLB miss fault */
>  		case 26:	/* PCXL: Data memory access rights trap */
>  		default:
> -			si.si_signo = SIGSEGV;
> -			si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
> +			signo = SIGSEGV;
> +			si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
>  			break;
>  		}
> -
>  #ifdef CONFIG_MEMORY_FAILURE
>  		if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
>  			unsigned int lsb = 0;
> @@ -409,12 +407,9 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
>  			return;
>  		}
>  #endif
> -
>  		show_signal_msg(regs, code, address, tsk, vma);
>  
> -		si.si_errno = 0;
> -		si.si_addr = (void __user *) address;
> -		force_sig_info(si.si_signo, &si, current);
> +		force_sig_fault(signo, si_code, (void __user *) address, current);
>  		return;
>  	}
>  
>