musl: fix GDB debugging on mips (local, remote)

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 48575

toolchain/musl/patches/020-ldso-fix-GDB-dynamic-linker-info-on-MIPS.patch

@@ -0,0 +1,55 @@
+From: Felix Fietkau <nbd@openwrt.org>
+Date: Sat, 30 Jan 2016 19:19:08 +0100
+Subject: [PATCH] ldso: fix GDB dynamic linker info on MIPS
+
+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>
+---
+
+--- 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__( \
+--- 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. */
+--- 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
+