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Commit ad722541 authored by Will Deacon's avatar Will Deacon Committed by Russell King
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ARM: 7456/1: ptrace: provide separate functions for tracing syscall {entry,exit} 



The syscall_trace on ARM takes a `why' parameter to indicate whether or
not we are entering or exiting a system call. This can be confusing for
people looking at the code since (a) it conflicts with the why register
alias in the entry assembly code and (b) it is not immediately clear
what it represents.

This patch splits up the syscall_trace function into separate wrappers
for syscall entry and exit, allowing the low-level syscall handling
code to branch to the appropriate function.

Reported-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 5125430c

arch/arm/kernel/entry-common.S

+6 −8
Original line number Original line Diff line number Diff line
@@ -442,10 +442,9 @@ ENDPROC(vector_swi) 
	 * context switches, and waiting for our parent to respond.

	 * context switches, and waiting for our parent to respond.

	 */

	 */

__sys_trace:

__sys_trace:

	mov	r2, scno

	mov	r1, scno

	add	r1, sp, #S_OFF

	add	r0, sp, #S_OFF

	mov	r0, #0				@ trace entry [IP = 0]

	bl	syscall_trace_enter

	bl	syscall_trace





	adr	lr, BSYM(__sys_trace_return)	@ return address

	adr	lr, BSYM(__sys_trace_return)	@ return address

	mov	scno, r0			@ syscall number (possibly new)

	mov	scno, r0			@ syscall number (possibly new)
@@ -457,10 +456,9 @@ __sys_trace: 




__sys_trace_return:

__sys_trace_return:

	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0

	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0

	mov	r2, scno

	mov	r1, scno

	mov	r1, sp

	mov	r0, sp

	mov	r0, #1				@ trace exit [IP = 1]

	bl	syscall_trace_exit

	bl	syscall_trace

	b	ret_slow_syscall

	b	ret_slow_syscall





	.align	5

	.align	5

arch/arm/kernel/ptrace.c

+25 −12
Original line number Original line Diff line number Diff line
@@ -907,12 +907,18 @@ long arch_ptrace(struct task_struct *child, long request, 
	return ret;

	return ret;

}

}





asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)

enum ptrace_syscall_dir {

	PTRACE_SYSCALL_ENTER = 0,

	PTRACE_SYSCALL_EXIT,

};



static int ptrace_syscall_trace(struct pt_regs *regs, int scno,

				enum ptrace_syscall_dir dir)

{

{

	unsigned long ip;

	unsigned long ip;





	if (!test_thread_flag(TIF_SYSCALL_TRACE))

	if (!test_thread_flag(TIF_SYSCALL_TRACE))

		goto out_no_trace;

		return scno;





	current_thread_info()->syscall = scno;

	current_thread_info()->syscall = scno;
@@ -921,21 +927,28 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno) 
	 * IP = 0 -> entry, =1 -> exit

	 * IP = 0 -> entry, =1 -> exit

	 */

	 */

	ip = regs->ARM_ip;

	ip = regs->ARM_ip;

	regs->ARM_ip = why;

	regs->ARM_ip = dir;





	if (why)

	if (dir == PTRACE_SYSCALL_EXIT)

		tracehook_report_syscall_exit(regs, 0);

		tracehook_report_syscall_exit(regs, 0);

	else if (tracehook_report_syscall_entry(regs))

	else if (tracehook_report_syscall_entry(regs))

		current_thread_info()->syscall = -1;

		current_thread_info()->syscall = -1;





	regs->ARM_ip = ip;

	regs->ARM_ip = ip;

	scno = current_thread_info()->syscall;

	return current_thread_info()->syscall;

}



asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)

{

	int ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_ENTER);

	audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0, regs->ARM_r1,

			    regs->ARM_r2, regs->ARM_r3);

	return ret;

}





out_no_trace:

asmlinkage int syscall_trace_exit(struct pt_regs *regs, int scno)

	if (why)

{

	int ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_EXIT);

	audit_syscall_exit(regs);

	audit_syscall_exit(regs);

	else

	return ret;

		audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0,

				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);

	return scno;

}
 
}