fix debugger tracking of shared libraries on mips with PIE main program

mips has its own mechanisms for DT_DEBUG because it makes _DYNAMIC
read-only, and the original mechanism, DT_MIPS_RLD_MAP, was
PIE-incompatible. DT_MIPS_RLD_MAP_REL was added to remedy this, but we
never implemented support for it. add it now using the same idioms for
mips-specific ldso logic.

arch/mips/reloc.h

@@ -29,6 +29,7 @@
 
 #define NEED_MIPS_GOT_RELOCS 1
 #define DT_DEBUG_INDIRECT DT_MIPS_RLD_MAP
+#define DT_DEBUG_INDIRECT_REL DT_MIPS_RLD_MAP_REL
 #define ARCH_SYM_REJECT_UND(s) (!((s)->st_other & STO_MIPS_PLT))
 
 #define CRTJMP(pc,sp) __asm__ __volatile__( \

arch/mips64/reloc.h

@@ -38,6 +38,7 @@
 
 #define NEED_MIPS_GOT_RELOCS 1
 #define DT_DEBUG_INDIRECT DT_MIPS_RLD_MAP
+#define DT_DEBUG_INDIRECT_REL DT_MIPS_RLD_MAP_REL
 #define ARCH_SYM_REJECT_UND(s) (!((s)->st_other & STO_MIPS_PLT))
 
 #define CRTJMP(pc,sp) __asm__ __volatile__( \

arch/mipsn32/reloc.h

@@ -29,6 +29,7 @@
 
 #define NEED_MIPS_GOT_RELOCS 1
 #define DT_DEBUG_INDIRECT DT_MIPS_RLD_MAP
+#define DT_DEBUG_INDIRECT_REL DT_MIPS_RLD_MAP_REL
 #define ARCH_SYM_REJECT_UND(s) (!((s)->st_other & STO_MIPS_PLT))
 
 #define CRTJMP(pc,sp) __asm__ __volatile__( \

ldso/dynlink.c

@@ -1992,6 +1992,10 @@ void __dls3(size_t *sp, size_t *auxv)
 			size_t *ptr = (size_t *) app.dynv[i+1];
 			*ptr = (size_t)&debug;
 		}
+		if (app.dynv[i]==DT_DEBUG_INDIRECT_REL) {
+			size_t *ptr = (size_t *)((size_t)&app.dynv[i] + app.dynv[i+1]);
+			*ptr = (size_t)&debug;
+		}
 	}
 
 	/* This must be done before final relocations, since it calls

src/internal/dynlink.h

@@ -92,6 +92,10 @@ struct fdpic_dummy_loadmap {
 #define DT_DEBUG_INDIRECT 0
 #endif
 
+#ifndef DT_DEBUG_INDIRECT_REL
+#define DT_DEBUG_INDIRECT_REL 0
+#endif
+
 #define AUX_CNT 32
 #define DYN_CNT 37