From de7ea4e414fe84bc9917c99c9faeca20baea3318 Mon Sep 17 00:00:00 2001
From: Edward Tomasz Napierala <trasz@FreeBSD.org>
Date: Thu, 4 Jul 2019 19:44:13 +0000
Subject: [PATCH] Implement PTRACE_GETSIGINFO.  This makes Linux strace(1)
 quieter in some cases (strace -f man id > /dev/null).

Reviewed by:	dchagin
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20691
---
 sys/amd64/linux/linux_ptrace.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/sys/amd64/linux/linux_ptrace.c b/sys/amd64/linux/linux_ptrace.c
index 054fad19334..ae7251899e3 100644
--- a/sys/amd64/linux/linux_ptrace.c
+++ b/sys/amd64/linux/linux_ptrace.c
@@ -68,6 +68,7 @@ __FBSDID("$FreeBSD$");
 #define	LINUX_PTRACE_DETACH		17
 #define	LINUX_PTRACE_SYSCALL		24
 #define	LINUX_PTRACE_SETOPTIONS		0x4200
+#define	LINUX_PTRACE_GETSIGINFO		0x4202
 #define	LINUX_PTRACE_GETREGSET		0x4204
 #define	LINUX_PTRACE_SEIZE		0x4206
 
@@ -366,6 +367,31 @@ linux_ptrace_setoptions(struct thread *td, pid_t pid, l_ulong data)
 	return (kern_ptrace(td, PT_SET_EVENT_MASK, pid, &mask, sizeof(mask)));
 }
 
+static int
+linux_ptrace_getsiginfo(struct thread *td, pid_t pid, l_ulong data)
+{
+	struct ptrace_lwpinfo lwpinfo;
+	l_siginfo_t l_siginfo;
+	int error, sig;
+
+	error = kern_ptrace(td, PT_LWPINFO, pid, &lwpinfo, sizeof(lwpinfo));
+	if (error != 0) {
+		linux_msg(td, "PT_LWPINFO failed with error %d", error);
+		return (error);
+	}
+
+	if ((lwpinfo.pl_flags & PL_FLAG_SI) == 0) {
+		error = EINVAL;
+		linux_msg(td, "no PL_FLAG_SI, returning %d", error);
+		return (error);
+	}
+
+	sig = bsd_to_linux_signal(lwpinfo.pl_siginfo.si_signo);
+	siginfo_to_lsiginfo(&lwpinfo.pl_siginfo, &l_siginfo, sig);
+	error = copyout(&l_siginfo, (void *)data, sizeof(l_siginfo));
+	return (error);
+}
+
 static int
 linux_ptrace_getregs(struct thread *td, pid_t pid, void *data)
 {
@@ -580,6 +606,9 @@ linux_ptrace(struct thread *td, struct linux_ptrace_args *uap)
 	case LINUX_PTRACE_SETOPTIONS:
 		error = linux_ptrace_setoptions(td, pid, uap->data);
 		break;
+	case LINUX_PTRACE_GETSIGINFO:
+		error = linux_ptrace_getsiginfo(td, pid, uap->data);
+		break;
 	case LINUX_PTRACE_GETREGSET:
 		error = linux_ptrace_getregset(td, pid, uap->addr, uap->data);
 		break;