Commit 02ce94c2 authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: fix system_call interaction with ptrace 



Don't overwrite return value if system call was cancelled at entry by
ptrace. Return status code from do_syscall_trace_enter so that
pt_regs::syscall doesn't need to be changed to skip syscall.

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent ba9c1d65

arch/xtensa/kernel/entry.S

+2 −2
Original line number Diff line number Diff line
@@ -1892,6 +1892,7 @@ ENTRY(system_call) 


	mov	a6, a2

	call4	do_syscall_trace_enter

	beqz	a6, .Lsyscall_exit

	l32i	a7, a2, PT_SYSCALL



1:
@@ -1904,8 +1905,6 @@ ENTRY(system_call) 


	addx4	a4, a7, a4

	l32i	a4, a4, 0

	movi	a5, sys_ni_syscall;

	beq	a4, a5, 1f



	/* Load args: arg0 - arg5 are passed via regs. */
@@ -1925,6 +1924,7 @@ ENTRY(system_call) 


	s32i	a6, a2, PT_AREG2

	bnez	a3, 1f

.Lsyscall_exit:

	abi_ret(4)



1:

arch/xtensa/kernel/ptrace.c

+16 −2
Original line number Diff line number Diff line
@@ -542,14 +542,28 @@ long arch_ptrace(struct task_struct *child, long request, 
	return ret;

}



void do_syscall_trace_enter(struct pt_regs *regs)

void do_syscall_trace_leave(struct pt_regs *regs);

int do_syscall_trace_enter(struct pt_regs *regs)

{

	if (regs->syscall == NO_SYSCALL)

		regs->areg[2] = -ENOSYS;



	if (test_thread_flag(TIF_SYSCALL_TRACE) &&

	    tracehook_report_syscall_entry(regs))

	    tracehook_report_syscall_entry(regs)) {

		regs->areg[2] = -ENOSYS;

		regs->syscall = NO_SYSCALL;

		return 0;

	}



	if (regs->syscall == NO_SYSCALL) {

		do_syscall_trace_leave(regs);

		return 0;

	}



	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))

		trace_sys_enter(regs, syscall_get_nr(current, regs));



	return 1;

}



void do_syscall_trace_leave(struct pt_regs *regs)

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