| Message ID | Ye4iHPb/sTm517LH@squeak.grove.modra.org |
|---|---|
| State | New |
| Headers | show |
| Series | [PowerPC64] Use medium model toc accesses throughout | expand |
On Sun, Jan 23, 2022 at 7:51 PM Alan Modra via Libc-alpha <libc-alpha@sourceware.org> wrote: > > The previous 2 patches got us to the point of segfaulting when trying > to transfer to main. > > start_addresses in sysdeps/powerpc/powerpc64/start.S is historical > baggage that should disappear. Until someone does that, relocating > stinfo->main by hand is one solution to the fact that the field may be > unrelocated at the time it is accessed. This is similar to what is > done for dynamic tags via the D_PTR macro. The makefile change is > needed to pick up elf/dl-static-tls.h from dl-machine.h. > > diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile > index fc7c29c695..93783cae00 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/Makefile > +++ b/sysdeps/unix/sysv/linux/powerpc/Makefile > @@ -27,3 +27,9 @@ tests += $(tests-static) > tests += test-gettimebasefreq > tests += test-powerpc-linux-sysconf > endif > + > +ifeq ($(subdir),csu) > +# to relocate stinfo->main > +CPPFLAGS-libc-start.o += -I../elf > +CPPFLAGS-libc-start.op += -I../elf > +endif > diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c > index bb97d16145..8f0d3a0eac 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c > +++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c > @@ -23,6 +23,10 @@ > #ifndef SHARED > #include <hwcapinfo.h> > #endif > +#if ENABLE_STATIC_PIE && !defined SHARED > +/* For elf_machine_load_address. */ > +#include <dl-machine.h> > +#endif > > /* The main work is done in the generic function. */ > #define LIBC_START_MAIN generic_start_main > @@ -95,8 +99,15 @@ __libc_start_main_impl (int argc, char **argv, > __tcb_parse_hwcap_and_convert_at_platform (); > #endif > > - return generic_start_main (stinfo->main, argc, argv, auxvec, > - stinfo->init, stinfo->fini, rtld_fini, > + void *main = stinfo->main; > +#if ENABLE_STATIC_PIE && !defined SHARED > + struct link_map *map = _dl_get_dl_main_map (); > + if (!map->l_relocated) > + main = (char *) main + elf_machine_load_address (); > +#endif Can you use __ehdr_start t here, similar to https://gitlab.com/x86-glibc/glibc/-/commit/1df93c500d0f81d30d1b7e323153512a8768bb72#ffb950808032d5085fdf882753d7bf8889e6a3d7 > + return generic_start_main (main, argc, argv, auxvec, > + NULL, NULL, rtld_fini, > stack_on_entry); > } > DEFINE_LIBC_START_MAIN_VERSION > > -- > Alan Modra > Australia Development Lab, IBM -- H.J.
On Sun, Jan 23, 2022 at 08:48:44PM -0800, H.J. Lu wrote: > On Sun, Jan 23, 2022 at 7:51 PM Alan Modra via Libc-alpha > > + void *main = stinfo->main; > > +#if ENABLE_STATIC_PIE && !defined SHARED > > + struct link_map *map = _dl_get_dl_main_map (); > > + if (!map->l_relocated) > > + main = (char *) main + elf_machine_load_address (); > > +#endif > > Can you use __ehdr_start t here, similar to > > https://gitlab.com/x86-glibc/glibc/-/commit/1df93c500d0f81d30d1b7e323153512a8768bb72#ffb950808032d5085fdf882753d7bf8889e6a3d7 That idea hadn't occurred to me. Yes, that likely would have worked too. I used the old traditional way of calculating l_addr, which happens to be quite cheap on powerpc64, but admittedly not so good on powerpc32.
diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile index fc7c29c695..93783cae00 100644 --- a/sysdeps/unix/sysv/linux/powerpc/Makefile +++ b/sysdeps/unix/sysv/linux/powerpc/Makefile @@ -27,3 +27,9 @@ tests += $(tests-static) tests += test-gettimebasefreq tests += test-powerpc-linux-sysconf endif + +ifeq ($(subdir),csu) +# to relocate stinfo->main +CPPFLAGS-libc-start.o += -I../elf +CPPFLAGS-libc-start.op += -I../elf +endif diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c index bb97d16145..8f0d3a0eac 100644 --- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c +++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c @@ -23,6 +23,10 @@ #ifndef SHARED #include <hwcapinfo.h> #endif +#if ENABLE_STATIC_PIE && !defined SHARED +/* For elf_machine_load_address. */ +#include <dl-machine.h> +#endif /* The main work is done in the generic function. */ #define LIBC_START_MAIN generic_start_main @@ -95,8 +99,15 @@ __libc_start_main_impl (int argc, char **argv, __tcb_parse_hwcap_and_convert_at_platform (); #endif - return generic_start_main (stinfo->main, argc, argv, auxvec, - stinfo->init, stinfo->fini, rtld_fini, + void *main = stinfo->main; +#if ENABLE_STATIC_PIE && !defined SHARED + struct link_map *map = _dl_get_dl_main_map (); + if (!map->l_relocated) + main = (char *) main + elf_machine_load_address (); +#endif + + return generic_start_main (main, argc, argv, auxvec, + NULL, NULL, rtld_fini, stack_on_entry); } DEFINE_LIBC_START_MAIN_VERSION