Commit b35f549d authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt (VMware)
Browse files

syscalls: Remove start and number from syscall_get_arguments() args 

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86 was horribly
written and not optimized for the standard case of passing in 0 and 6 for
the starting index and the number of system calls to get. When looking at
all the users of this function, I discovered that all instances pass in only
0 and 6 for these arguments. Instead of having this function handle
different cases that are never used, simply rewrite it to return the first 6
arguments of a system call.

This should help out the performance of tracing system calls by ptrace,
ftrace and perf.

Link: http://lkml.kernel.org/r/20161107213233.754809394@goodmis.org



Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Dave Martin <dave.martin@arm.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Acked-by: Paul Burton <paul.burton@mips.com> # MIPS parts
Acked-by: Max Filippov <jcmvbkbc@gmail.com> # For xtensa changes
Acked-by: Will Deacon <will.deacon@arm.com> # For the arm64 bits
Reviewed-by: Thomas Gleixner <tglx@linutronix.de> # for x86
Reviewed-by: default avatarDmitry V. Levin <ldv@altlinux.org>
Reported-by: default avatarAndy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent ed3bb007

arch/arc/include/asm/syscall.h

+3 −4
Original line number Diff line number Diff line
@@ -55,12 +55,11 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, 
 */

static inline void

syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,

		      unsigned int i, unsigned int n, unsigned long *args)

		      unsigned long *args)

{

	unsigned long *inside_ptregs = &(regs->r0);

	inside_ptregs -= i;



	BUG_ON((i + n) > 6);

	unsigned int n = 6;

	unsigned int i = 0;



	while (n--) {

		args[i++] = (*inside_ptregs);

arch/arm/include/asm/syscall.h

+3 −20
Original line number Diff line number Diff line
@@ -55,29 +55,12 @@ static inline void syscall_set_return_value(struct task_struct *task, 


static inline void syscall_get_arguments(struct task_struct *task,

					 struct pt_regs *regs,

					 unsigned int i, unsigned int n,

					 unsigned long *args)

{

	if (n == 0)

		return;



	if (i + n > SYSCALL_MAX_ARGS) {

		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;

		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;

		pr_warn("%s called with max args %d, handling only %d\n",

			__func__, i + n, SYSCALL_MAX_ARGS);

		memset(args_bad, 0, n_bad * sizeof(args[0]));

		n = SYSCALL_MAX_ARGS - i;

	}



	if (i == 0) {

	args[0] = regs->ARM_ORIG_r0;

	args++;

		i++;

		n--;

	}



	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));

	memcpy(args, &regs->ARM_r0 + 1, 5 * sizeof(args[0]));

}



static inline void syscall_set_arguments(struct task_struct *task,

arch/arm64/include/asm/syscall.h

+3 −19
Original line number Diff line number Diff line
@@ -65,28 +65,12 @@ static inline void syscall_set_return_value(struct task_struct *task, 


static inline void syscall_get_arguments(struct task_struct *task,

					 struct pt_regs *regs,

					 unsigned int i, unsigned int n,

					 unsigned long *args)

{

	if (n == 0)

		return;



	if (i + n > SYSCALL_MAX_ARGS) {

		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;

		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;

		pr_warning("%s called with max args %d, handling only %d\n",

			   __func__, i + n, SYSCALL_MAX_ARGS);

		memset(args_bad, 0, n_bad * sizeof(args[0]));

	}



	if (i == 0) {

	args[0] = regs->orig_x0;

	args++;

		i++;

		n--;

	}



	memcpy(args, &regs->regs[i], n * sizeof(args[0]));

	memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));

}



static inline void syscall_set_arguments(struct task_struct *task,

arch/c6x/include/asm/syscall.h

+8 −33
Original line number Diff line number Diff line
@@ -46,40 +46,15 @@ static inline void syscall_set_return_value(struct task_struct *task, 
}



static inline void syscall_get_arguments(struct task_struct *task,

					 struct pt_regs *regs, unsigned int i,

					 unsigned int n, unsigned long *args)

					 struct pt_regs *regs,

					 unsigned long *args)

{

	switch (i) {

	case 0:

		if (!n--)

			break;

	*args++ = regs->a4;

	case 1:

		if (!n--)

			break;

	*args++ = regs->b4;

	case 2:

		if (!n--)

			break;

	*args++ = regs->a6;

	case 3:

		if (!n--)

			break;

	*args++ = regs->b6;

	case 4:

		if (!n--)

			break;

	*args++ = regs->a8;

	case 5:

		if (!n--)

			break;

		*args++ = regs->b8;

	case 6:

		if (!n--)

			break;

	default:

		BUG();

	}

	*args   = regs->b8;

}



static inline void syscall_set_arguments(struct task_struct *task,

arch/csky/include/asm/syscall.h

+4 −10
Original line number Diff line number Diff line
@@ -43,17 +43,11 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, 


static inline void

syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,

		      unsigned int i, unsigned int n, unsigned long *args)

		      unsigned long *args)

{

	BUG_ON(i + n > 6);

	if (i == 0) {

	args[0] = regs->orig_a0;

	args++;

		n--;

	} else {

		i--;

	}

	memcpy(args, &regs->a1 + i, n * sizeof(args[0]));

	memcpy(args, &regs->a1, 5 * sizeof(args[0]));

}



static inline void

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