git: 895080484248 - main - rtld: allow to use tls_get_addr_slow() from context where rtld_bind_lock is locked

[Konstantin Belousov]

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=89508048424837ffdb32c8444dab02261711f77d

commit 89508048424837ffdb32c8444dab02261711f77d
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-04-06 18:56:58 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-04-09 20:46:24 +0000

    rtld: allow to use tls_get_addr_slow() from context where rtld_bind_lock is locked
    
    Explicit locked parameter is added
    
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
    Differential revision:  https://reviews.freebsd.org/D29623
---
 libexec/rtld-elf/rtld.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 8b03616993d2..8c8271abc93e 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -166,6 +166,7 @@ static int symlook_list(SymLook *, const Objlist *, DoneList *);
 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
 static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
 static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
+static void *tls_get_addr_slow(Elf_Addr **, int, size_t, bool) __noinline;
 static void trace_loaded_objects(Obj_Entry *);
 static void unlink_object(Obj_Entry *);
 static void unload_object(Obj_Entry *, RtldLockState *lockstate);
@@ -4871,9 +4872,8 @@ unref_dag(Obj_Entry *root)
 /*
  * Common code for MD __tls_get_addr().
  */
-static void *tls_get_addr_slow(Elf_Addr **, int, size_t) __noinline;
 static void *
-tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
+tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset, bool locked)
 {
 	Elf_Addr *newdtv, *dtv;
 	RtldLockState lockstate;
@@ -4882,7 +4882,8 @@ tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
 	dtv = *dtvp;
 	/* Check dtv generation in case new modules have arrived */
 	if (dtv[0] != tls_dtv_generation) {
-		wlock_acquire(rtld_bind_lock, &lockstate);
+		if (!locked)
+			wlock_acquire(rtld_bind_lock, &lockstate);
 		newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
 		to_copy = dtv[1];
 		if (to_copy > tls_max_index)
@@ -4891,17 +4892,20 @@ tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
 		newdtv[0] = tls_dtv_generation;
 		newdtv[1] = tls_max_index;
 		free(dtv);
-		lock_release(rtld_bind_lock, &lockstate);
+		if (!locked)
+			lock_release(rtld_bind_lock, &lockstate);
 		dtv = *dtvp = newdtv;
 	}
 
 	/* Dynamically allocate module TLS if necessary */
 	if (dtv[index + 1] == 0) {
 		/* Signal safe, wlock will block out signals. */
-		wlock_acquire(rtld_bind_lock, &lockstate);
+		if (!locked)
+			wlock_acquire(rtld_bind_lock, &lockstate);
 		if (!dtv[index + 1])
 			dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
-		lock_release(rtld_bind_lock, &lockstate);
+		if (!locked)
+			lock_release(rtld_bind_lock, &lockstate);
 	}
 	return ((void *)(dtv[index + 1] + offset));
 }
@@ -4916,7 +4920,7 @@ tls_get_addr_common(Elf_Addr **dtvp, int index, size_t offset)
 	if (__predict_true(dtv[0] == tls_dtv_generation &&
 	    dtv[index + 1] != 0))
 		return ((void *)(dtv[index + 1] + offset));
-	return (tls_get_addr_slow(dtvp, index, offset));
+	return (tls_get_addr_slow(dtvp, index, offset, false));
 }
 
 #if defined(__aarch64__) || defined(__arm__) || defined(__mips__) || \