From: Max Filippov jcmvbkbc@gmail.com
[ Upstream commit 02ce94c229251555ac726ecfebe3458ef5905fa9 ]
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: Max Filippov jcmvbkbc@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/xtensa/kernel/entry.S | 4 ++-- arch/xtensa/kernel/ptrace.c | 18 ++++++++++++++++-- 2 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 59671603c9c62..1f07876ea2ed7 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -1897,6 +1897,7 @@ ENTRY(system_call)
mov a6, a2 call4 do_syscall_trace_enter + beqz a6, .Lsyscall_exit l32i a7, a2, PT_SYSCALL
1: @@ -1911,8 +1912,6 @@ 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. */
@@ -1932,6 +1931,7 @@ ENTRY(system_call)
s32i a6, a2, PT_AREG2 bnez a3, 1f +.Lsyscall_exit: abi_ret(4)
1: diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c index b964f0b2d8864..145742d70a9f2 100644 --- a/arch/xtensa/kernel/ptrace.c +++ b/arch/xtensa/kernel/ptrace.c @@ -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)