Date: Tue, 26 Nov 2013 10:09:53 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: FreeBSD Current <freebsd-current@FreeBSD.org>, Luca Pizzamiglio <luca.pizzamiglio@gmail.com> Subject: Re: gdb has outdated knowledge of signal trampolines Message-ID: <20131126080953.GS59496@kib.kiev.ua> In-Reply-To: <20131125173527.GP59496@kib.kiev.ua> References: <529322E1.1060105@FreeBSD.org> <20131125173527.GP59496@kib.kiev.ua>
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On Mon, Nov 25, 2013 at 07:35:27PM +0200, Konstantin Belousov wrote:
> Could you update your gdb patch to use the KERN_PROC_SIGTRAMP from
> the patch below ? If this works out, I will add initialization of
> sv_szsigcode for ABIs which do not use shared page.
Below is the complete patch. With it applied, I get
(gdb) bt
#0 sighandler (signo=3D1, info=3D0x7fffffffd2b0, context=3DUnhandled dwarf=
expression opcode 0xf3
) at siginfo.c:34
#1 <signal handler called>
#2 0x000000080088849a in sigsuspend () from /lib/libc.so.7
#3 0x000000000040093a in main (argc=3DUnhandled dwarf expression opcode 0x=
f3
) at siginfo.c:54
diff --git a/contrib/gdb/gdb/amd64fbsd-nat.c b/contrib/gdb/gdb/amd64fbsd-na=
t.c
index f083734..dacd4a3 100644
--- a/contrib/gdb/gdb/amd64fbsd-nat.c
+++ b/contrib/gdb/gdb/amd64fbsd-nat.c
@@ -29,6 +29,7 @@
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
+#include <sys/user.h>
#include <machine/reg.h>
=20
#ifdef HAVE_SYS_PROCFS_H
@@ -212,24 +213,23 @@ Please report this to <bug-gdb@gnu.org>.",
=20
SC_RBP_OFFSET =3D offset;
=20
- /* FreeBSD provides a kern.ps_strings sysctl that we can use to
+ /* FreeBSD provides a kern.proc.sigtramp sysctl that we can use to
locate the sigtramp. That way we can still recognize a sigtramp
- if its location is changed in a new kernel. Of course this is
- still based on the assumption that the sigtramp is placed
- directly under the location where the program arguments and
- environment can be found. */
+ if its location is changed in a new kernel. */
{
- int mib[2];
- long ps_strings;
+ int mib[4];
+ struct kinfo_sigtramp kst;
size_t len;
=20
mib[0] =3D CTL_KERN;
- mib[1] =3D KERN_PS_STRINGS;
- len =3D sizeof (ps_strings);
- if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) =3D=3D 0)
+ mib[1] =3D KERN_PROC;
+ mib[2] =3D KERN_PROC_SIGTRAMP;
+ mib[3] =3D getpid();
+ len =3D sizeof (kst);
+ if (sysctl (mib, sizeof(mib) / sizeof(mib[0]), &kst, &len, NULL, 0) =
=3D=3D 0)
{
- amd64fbsd_sigtramp_start_addr =3D ps_strings - 32;
- amd64fbsd_sigtramp_end_addr =3D ps_strings;
+ amd64fbsd_sigtramp_start_addr =3D kst.ksigtramp_start;
+ amd64fbsd_sigtramp_end_addr =3D kst.ksigtramp_end;
}
}
}
diff --git a/sys/amd64/include/pcb.h b/sys/amd64/include/pcb.h
index c106edc..80aff86 100644
--- a/sys/amd64/include/pcb.h
+++ b/sys/amd64/include/pcb.h
@@ -43,6 +43,7 @@
#include <machine/fpu.h>
#include <machine/segments.h>
=20
+#ifdef __amd64__
struct pcb {
register_t pcb_r15;
register_t pcb_r14;
@@ -105,6 +106,7 @@ struct pcb {
=20
uint64_t pcb_pad[3];
};
+#endif
=20
#ifdef _KERNEL
struct trapframe;
diff --git a/sys/amd64/include/segments.h b/sys/amd64/include/segments.h
index d9f4280..6bcadc7 100644
--- a/sys/amd64/include/segments.h
+++ b/sys/amd64/include/segments.h
@@ -82,8 +82,8 @@ struct soft_segment_descriptor {
* region descriptors, used to load gdt/idt tables before segments yet exi=
st.
*/
struct region_descriptor {
- unsigned long rd_limit:16; /* segment extent */
- unsigned long rd_base:64 __packed; /* base address */
+ uint64_t rd_limit:16; /* segment extent */
+ uint64_t rd_base:64 __packed; /* base address */
} __packed;
=20
#ifdef _KERNEL
diff --git a/sys/compat/freebsd32/freebsd32.h b/sys/compat/freebsd32/freebs=
d32.h
index 8376e95..94f886e 100644
--- a/sys/compat/freebsd32/freebsd32.h
+++ b/sys/compat/freebsd32/freebsd32.h
@@ -362,6 +362,12 @@ struct kinfo_proc32 {
int ki_tdflags;
};
=20
+struct kinfo_sigtramp32 {
+ uint32_t ksigtramp_start;
+ uint32_t ksigtramp_end;
+ uint32_t ksigtramp_spare[4];
+};
+
struct kld32_file_stat_1 {
int version; /* set to sizeof(struct kld_file_stat_1) */
char name[MAXPATHLEN];
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index 9968e76..2e6bc32 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -2632,6 +2632,60 @@ errout:
return (error);
}
=20
+static int
+sysctl_kern_proc_sigtramp(SYSCTL_HANDLER_ARGS)
+{
+ int *name =3D (int *)arg1;
+ u_int namelen =3D arg2;
+ struct proc *p;
+ struct kinfo_sigtramp kst;
+ const struct sysentvec *sv;
+ int error;
+#ifdef COMPAT_FREEBSD32
+ struct kinfo_sigtramp32 kst32;
+#endif
+
+ if (namelen !=3D 1)
+ return (EINVAL);
+
+ error =3D pget((pid_t)name[0], PGET_CANDEBUG, &p);
+ if (error !=3D 0)
+ return (error);
+ sv =3D p->p_sysent;
+#ifdef COMPAT_FREEBSD32
+ if ((req->flags & SCTL_MASK32) !=3D 0) {
+ bzero(&kst32, sizeof(kst32));
+ if (SV_PROC_FLAG(p, SV_ILP32)) {
+ if (sv->sv_sigcode_base !=3D 0) {
+ kst32.ksigtramp_start =3D sv->sv_sigcode_base;
+ kst32.ksigtramp_end =3D sv->sv_sigcode_base +
+ *sv->sv_szsigcode;
+ } else {
+ kst32.ksigtramp_start =3D sv->sv_psstrings -
+ *sv->sv_szsigcode;
+ kst32.ksigtramp_end =3D sv->sv_psstrings;
+ }
+ }
+ PROC_UNLOCK(p);
+ error =3D SYSCTL_OUT(req, &kst32, sizeof(kst32));
+ return (error);
+ }
+#endif
+ bzero(&kst, sizeof(kst));
+ if (sv->sv_sigcode_base !=3D 0) {
+ kst.ksigtramp_start =3D (char *)sv->sv_sigcode_base;
+ kst.ksigtramp_end =3D (char *)sv->sv_sigcode_base +
+ *sv->sv_szsigcode;
+ } else {
+ kst.ksigtramp_start =3D (char *)sv->sv_psstrings -
+ *sv->sv_szsigcode;
+ kst.ksigtramp_end =3D (char *)sv->sv_psstrings;
+ }
+ PROC_UNLOCK(p);
+ error =3D SYSCTL_OUT(req, &kst, sizeof(kst));
+ return (error);
+}
+
SYSCTL_NODE(_kern, KERN_PROC, proc, CTLFLAG_RD, 0, "Process table");
=20
SYSCTL_PROC(_kern_proc, KERN_PROC_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT|
@@ -2740,3 +2794,7 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC_UMASK, umask=
, CTLFLAG_RD |
static SYSCTL_NODE(_kern_proc, KERN_PROC_OSREL, osrel, CTLFLAG_RW |
CTLFLAG_ANYBODY | CTLFLAG_MPSAFE, sysctl_kern_proc_osrel,
"Process binary osreldate");
+
+static SYSCTL_NODE(_kern_proc, KERN_PROC_SIGTRAMP, sigtramp, CTLFLAG_RD |
+ CTLFLAG_MPSAFE, sysctl_kern_proc_sigtramp,
+ "Process signal trampoline location");
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index 64292ba..8e70a12 100644
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -530,6 +530,7 @@ SYSCTL_ALLOWED_TYPES(UINT64, uint64_t *a; unsigned long=
long *b; );
#define KERN_PROC_PS_STRINGS 38 /* get ps_strings location */
#define KERN_PROC_UMASK 39 /* process umask */
#define KERN_PROC_OSREL 40 /* osreldate for process binary */
+#define KERN_PROC_SIGTRAMP 41 /* signal trampoline location */
=20
/*
* KERN_IPC identifiers
diff --git a/sys/sys/user.h b/sys/sys/user.h
index d2e2b6e..e926fe8 100644
--- a/sys/sys/user.h
+++ b/sys/sys/user.h
@@ -498,6 +498,12 @@ struct kinfo_kstack {
int _kkst_ispare[16]; /* Space for more stuff. */
};
=20
+struct kinfo_sigtramp {
+ void *ksigtramp_start;
+ void *ksigtramp_end;
+ void *ksigtramp_spare[4];
+};
+
#ifdef _KERNEL
/* Flags for kern_proc_out function. */
#define KERN_PROC_NOTHREADS 0x1
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