Add the ability for GDB to printout the thread name along with other

thread specific informations.

In order to do that, and in order to avoid KBI breakage with existing
infrastructure the following semantic is implemented:
- For live programs, a new member to the PT_LWPINFO is added (pl_tdname)
- For cores, a new ELF note is added (NT_THRMISC) that can be used for
  storing thread specific, miscellaneous, informations. Right now it is
  just popluated with a thread name.

GDB, then, retrieves the correct informations from the corefile via the
BFD interface, as it groks the ELF notes and create appropriate
pseudo-sections.

Sponsored by:	Sandvine Incorporated
Tested by:	gianni
Discussed with:	dim, kan, kib
MFC after:	2 weeks

2 files changed, 13 insertions, 0 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index e29ddfa..42f5573 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -1316,12 +1316,14 @@ typedef struct prpsinfo32 elf_prpsinfo_t;
 typedef struct fpreg32 elf_prfpregset_t;
 typedef struct fpreg32 elf_fpregset_t;
 typedef struct reg32 elf_gregset_t;
+typedef struct thrmisc32 elf_thrmisc_t;
 #else
 typedef prstatus_t elf_prstatus_t;
 typedef prpsinfo_t elf_prpsinfo_t;
 typedef prfpregset_t elf_prfpregset_t;
 typedef prfpregset_t elf_fpregset_t;
 typedef gregset_t elf_gregset_t;
+typedef thrmisc_t elf_thrmisc_t;
 #endif
 
 static void
@@ -1331,10 +1333,12 @@ __elfN(puthdr)(struct thread *td, void *dst, size_t *off, int numsegs)
 		elf_prstatus_t status;
 		elf_prfpregset_t fpregset;
 		elf_prpsinfo_t psinfo;
+		elf_thrmisc_t thrmisc;
 	} *tempdata;
 	elf_prstatus_t *status;
 	elf_prfpregset_t *fpregset;
 	elf_prpsinfo_t *psinfo;
+	elf_thrmisc_t *thrmisc;
 	struct proc *p;
 	struct thread *thr;
 	size_t ehoff, noteoff, notesz, phoff;
@@ -1357,11 +1361,13 @@ __elfN(puthdr)(struct thread *td, void *dst, size_t *off, int numsegs)
 		status = &tempdata->status;
 		fpregset = &tempdata->fpregset;
 		psinfo = &tempdata->psinfo;
+		thrmisc = &tempdata->thrmisc;
 	} else {
 		tempdata = NULL;
 		status = NULL;
 		fpregset = NULL;
 		psinfo = NULL;
+		thrmisc = NULL;
 	}
 
 	if (dst != NULL) {
@@ -1401,11 +1407,15 @@ __elfN(puthdr)(struct thread *td, void *dst, size_t *off, int numsegs)
 			fill_regs(thr, &status->pr_reg);
 			fill_fpregs(thr, fpregset);
 #endif
+			memset(&thrmisc->_pad, 0, sizeof (thrmisc->_pad));
+			strcpy(thrmisc->pr_tname, thr->td_name);
 		}
 		__elfN(putnote)(dst, off, "FreeBSD", NT_PRSTATUS, status,
 		    sizeof *status);
 		__elfN(putnote)(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
 		    sizeof *fpregset);
+		__elfN(putnote)(dst, off, "FreeBSD", NT_THRMISC, thrmisc,
+		    sizeof *thrmisc);
 		/*
 		 * Allow for MD specific notes, as well as any MD
 		 * specific preparations for writing MI notes.
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index af6b298..e5d9842 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -93,6 +93,7 @@ struct ptrace_lwpinfo32 {
 	sigset_t	pl_sigmask;	/* LWP signal mask */
 	sigset_t	pl_siglist;	/* LWP pending signal */
 	struct siginfo32 pl_siginfo;	/* siginfo for signal */
+	char	pl_tdname[MAXCOMLEN + 1];	/* LWP name. */
 };
 
 #endif
@@ -520,6 +521,7 @@ ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl,
 	pl32->pl_sigmask = pl->pl_sigmask;
 	pl32->pl_siglist = pl->pl_siglist;
 	siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
+	strcpy(pl32->pl_tdname, pl->pl_tdname);
 }
 #endif /* COMPAT_FREEBSD32 */
 
@@ -1164,6 +1166,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 			pl->pl_flags |= PL_FLAG_EXEC;
 		pl->pl_sigmask = td2->td_sigmask;
 		pl->pl_siglist = td2->td_siglist;
+		strcpy(pl->pl_tdname, td2->td_name);
 #ifdef COMPAT_FREEBSD32
 		if (wrap32)
 			ptrace_lwpinfo_to32(pl, pl32);