2015-11-15 Helge Deller John David Anglin PR libc/19170 * sysdeps/hppa/crti.S (gmon_initializer): New. Use .init_array support to call gmon_initializer. Only call __gmon_start__ when symbol is defined at runtime. * sysdeps/hppa/crtn.S (__gmon_start__): Delete. * sysdeps/hppa/dl-lookupcfg.h (DL_FIXUP_MAKE_VALUE): Provide null function descriptor when MAP argument is null. * sysdeps/hppa/dl-trampoline.S (_dl_runtime_resolve): Return directly to previous function when function is undefined. diff --git a/sysdeps/hppa/crti.S b/sysdeps/hppa/crti.S index 98f1af5..568a999 100644 --- a/sysdeps/hppa/crti.S +++ b/sysdeps/hppa/crti.S @@ -49,6 +49,95 @@ # define PREINIT_FUNCTION_WEAK 1 #endif +#if PREINIT_FUNCTION_WEAK + weak_extern (PREINIT_FUNCTION) +#else + .hidden PREINIT_FUNCTION +#endif + + +/* If we have working .init_array support, we want to keep the .init + section empty (apart from the mandatory prologue/epilogue. This + ensures that the default unwind conventions (return-pointer in b0, + frame state in ar.pfs, etc.) will do the Right Thing. To ensure + an empty .init section, we register gmon_initializer() via the + .init_array. + + --davidm 02/10/29 */ + +#if PREINIT_FUNCTION_WEAK +/* This blob of assembly code is one simple C function: + +static void +__attribute__ ((used)) +gmon_initializer (void) +{ + extern void weak_function __gmon_start__ (void); + + if (__gmon_start__) + (*__gmon_start__)(); +} + +In a final executable, PLABEL32 relocations for function pointers are +resolved at link time. Typically, binutils/ld resolves __gmon_start__ +using an external shared library. __gmon_start__ is always called if +it is found at link time. If __gmon_start__ is not found at runtime +due to a library update, then the function pointer will point at a null +function descriptor and calling it will cause a segmentation fault. +So, we call __canonicalize_funcptr_for_compare to obtain the canonicalized +address of __gmon_start__ and skip calling __gmon_start__ if it is zero. + + */ + .type __canonicalize_funcptr_for_compare,@function + .type $$dyncall,@function + + .section .data.rel.ro,"aw",@progbits + .align 4 +.LC0: + .type __gmon_start__,@function + .word P%__gmon_start__ + + .text + .align 4 + .type gmon_initializer,@function +gmon_initializer: + .PROC + .CALLINFO FRAME=64,CALLS,SAVE_RP,ENTRY_GR=4 + .ENTRY + stw %r2,-20(%r30) + stwm %r4,64(%r30) + stw %r3,-60(%r30) + addil LT'.LC0,%r19 + ldw RT'.LC0(%r1),%r28 + ldw 0(%r28),%r3 + comib,= 0,%r3,1f + copy %r19,%r4 + stw %r19,-32(%r30) + bl __canonicalize_funcptr_for_compare,%r2 + copy %r3,%r26 + comib,= 0,%r28,1f + copy %r4,%r19 + copy %r3,%r22 + .CALL ARGW0=GR + bl $$dyncall,%r31 + copy %r31,%r2 +1: + ldw -84(%r30),%r2 + ldw -60(%r30),%r3 + bv %r0(%r2) + ldwm -64(%r30),%r4 + .EXIT + .PROCEND + .size gmon_initializer, .-gmon_initializer + +# undef PREINIT_FUNCTION +# define PREINIT_FUNCTION gmon_initializer +#endif + + .section .init_array, "aw" + .word P% PREINIT_FUNCTION + + /* _init prologue. */ .section .init, "ax", %progbits .align 4 @@ -58,14 +147,6 @@ _init: stw %rp,-20(%sp) stwm %r4,64(%sp) stw %r19,-32(%sp) -#if PREINIT_FUNCTION_WEAK - bl PREINIT_FUNCTION,%rp - copy %r19,%r4 /* delay slot */ -#else - bl PREINIT_FUNCTION,%rp - copy %r19,%r4 /* delay slot */ -#endif - copy %r4,%r19 /* _fini prologue. */ .section .fini,"ax",%progbits diff --git a/sysdeps/hppa/crtn.S b/sysdeps/hppa/crtn.S index e0d345f..a410425 100644 --- a/sysdeps/hppa/crtn.S +++ b/sysdeps/hppa/crtn.S @@ -38,27 +38,6 @@ /* crtn.S puts function epilogues in the .init and .fini sections corresponding to the prologues in crti.S. */ -/* Note that we cannot have a weak undefined __gmon_start__, because - that would require this to be PIC, and the linker is currently not - able to generate a proper procedure descriptor for _init. Sad but - true. Anyway, HPPA is one of those horrible architectures where - making the comparison and indirect call is quite expensive (see the - comment in sysdeps/generic/initfini.c). */ - .text - .align 4 - .weak __gmon_start__ - .type __gmon_start__,@function -__gmon_start__: - .proc - .callinfo - .entry - bv,n %r0(%r2) - .exit - .procend - -/* Here is the tail end of _init. We put __gmon_start before this so - that the assembler creates the .PARISC.unwind section for us, ie. - with the right attributes. */ .section .init, "ax", @progbits ldw -84(%sp),%rp copy %r4,%r19 diff --git a/sysdeps/hppa/dl-lookupcfg.h b/sysdeps/hppa/dl-lookupcfg.h index c36928c..dea1809 100644 --- a/sysdeps/hppa/dl-lookupcfg.h +++ b/sysdeps/hppa/dl-lookupcfg.h @@ -75,7 +75,9 @@ void attribute_hidden _dl_unmap (struct link_map *map); /* Construct a fixup value from the address and linkmap */ #define DL_FIXUP_MAKE_VALUE(map, addr) \ - ((struct fdesc) { (addr), (map)->l_info[DT_PLTGOT]->d_un.d_ptr }) + (map) ? ((struct fdesc) { (addr), (map)->l_info[DT_PLTGOT]->d_un.d_ptr }) \ + : ((struct fdesc) { 0, 0 }) + /* Extract the code address from a fixup value */ #define DL_FIXUP_VALUE_CODE_ADDR(value) ((value).ip) diff --git a/sysdeps/hppa/dl-trampoline.S b/sysdeps/hppa/dl-trampoline.S index 22f484a..64f0966 100644 --- a/sysdeps/hppa/dl-trampoline.S +++ b/sysdeps/hppa/dl-trampoline.S @@ -82,6 +82,11 @@ _dl_runtime_resolve: bl _dl_fixup,%rp copy %r21,%r19 /* set fixup func ltp */ + /* Sometimes a final executable may attempt to call an undefined + weak function (e.g., __gmon_start__). Return if the function + was not resolved by _dl_fixup */ + comib,= 0,%r28,1f + /* Load up the returned func descriptor */ copy %r28, %r22 copy %r29, %r19 @@ -107,6 +112,13 @@ _dl_runtime_resolve: /* Jump to new function, but return to previous function */ bv %r0(%r22) ldw -20(%sp),%rp + +1: + /* Return to previous function */ + ldw -148(%sp),%rp + bv %r0(%rp) + ldo -128(%sp),%sp + .EXIT .PROCEND cfi_endproc