[PATCH v3] ldso: fix GDB dynamic linker info on MIPS

[Felix Fietkau <nbd@openwrt.org>]

GDB is looking for a pointer to the ldso debug info in the data of the
.rld_map section.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 arch/mips/reloc.h      |  2 +-
 ldso/dynlink.c         | 11 +++++++----
 src/internal/dynlink.h |  4 ++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/mips/reloc.h b/arch/mips/reloc.h
index 9b40e3d..8c52df0 100644
--- a/arch/mips/reloc.h
+++ b/arch/mips/reloc.h
@@ -24,7 +24,7 @@
 #define REL_TPOFF       R_MIPS_TLS_TPREL32
 
 #define NEED_MIPS_GOT_RELOCS 1
-#define DYNAMIC_IS_RO 1
+#define DT_DEBUG_INDIRECT DT_MIPS_RLD_MAP
 #define ARCH_SYM_REJECT_UND(s) (!((s)->st_other & STO_MIPS_PLT))
 
 #define CRTJMP(pc,sp) __asm__ __volatile__( \
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index f497542..87f3b7f 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1582,11 +1582,14 @@ _Noreturn void __dls3(size_t *sp)
 	load_deps(&app);
 	make_global(&app);
 
-#ifndef DYNAMIC_IS_RO
-	for (i=0; app.dynv[i]; i+=2)
-		if (app.dynv[i]==DT_DEBUG)
+	for (i=0; app.dynv[i]; i+=2) {
+		if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
 			app.dynv[i+1] = (size_t)&debug;
-#endif
+		if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
+			size_t *ptr = (size_t *) app.dynv[i+1];
+			*ptr = (size_t)&debug;
+		}
+	}
 
 	/* The main program must be relocated LAST since it may contin
 	 * copy relocations which depend on libraries' relocations. */
diff --git a/src/internal/dynlink.h b/src/internal/dynlink.h
index 9c494e4..48890b2 100644
--- a/src/internal/dynlink.h
+++ b/src/internal/dynlink.h
@@ -83,6 +83,10 @@ struct fdpic_dummy_loadmap {
 #define NEED_MIPS_GOT_RELOCS 0
 #endif
 
+#ifndef DT_DEBUG_INDIRECT
+#define DT_DEBUG_INDIRECT 0
+#endif
+
 #define AUX_CNT 32
 #define DYN_CNT 32
 
-- 
2.2.2