From 696caf1d002ff059ddd20fd5eaccd76229c14850 Mon Sep 17 00:00:00 2001 From: Ulrich Weigand Date: Wed, 4 Dec 2013 06:51:11 -0600 Subject: PowerPC64 ELFv2 ABI 2/6: Remove function descriptors This patch adds support for the ELFv2 ABI feature to remove function descriptors. See this GCC patch for in-depth discussion: http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01141.html This mostly involves two types of changes: updating assembler source files to the new logic, and updating the dynamic loader. After the refactoring in the previous patch, most of the assembler source changes can be handled simply by providing ELFv2 versions of the macros in sysdep.h. One somewhat non-obvious change is in __GI__setjmp: this used to "fall through" to the immediately following __setjmp ENTRY point. This is no longer safe in the ELFv2 since ENTRY defines both a global and a local entry point, and you cannot simply fall through to a global entry point as it requires r12 to be set up. Also, makecontext needs to be updated to set up registers according to the new ABI for calling into the context's start routine. The dynamic linker changes mostly consist of removing special code to handle function descriptors. We also need to support the new PLT and glink format used by the the ELFv2 linker, see: https://sourceware.org/ml/binutils/2013-10/msg00376.html In addition, the dynamic linker now verifies that the dynamic libraries it loads match its own ABI. The hack in VDSO_IFUNC_RET to "synthesize" a function descriptor for vDSO routines is also no longer necessary for ELFv2. --- sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h | 2 +- sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h | 4 ++++ sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S | 7 +++++++ 3 files changed, 12 insertions(+), 1 deletion(-) (limited to 'sysdeps/unix/sysv') diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h index d189169..31dd15e 100644 --- a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h +++ b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h @@ -41,7 +41,7 @@ extern void *__vdso_sigtramp32; extern void *__vdso_sigtramp_rt32; #endif -#if defined(__PPC64__) || defined(__powerpc64__) +#if (defined(__PPC64__) || defined(__powerpc64__)) && _CALL_ELF != 2 /* The correct solution is for _dl_vdso_vsym to return the address of the OPD for the kernel VDSO function. That address would then be stored in the __vdso_* variables and returned as the result of the IFUNC resolver function. diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h b/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h index 4263b1a..d043968 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h @@ -23,6 +23,8 @@ /* Now define our stuff. */ +#if _CALL_ELF != 2 + static __always_inline bool _dl_ppc64_is_opd_sym (const struct link_map *l, const ElfW(Sym) *sym) { @@ -73,4 +75,6 @@ _dl_ppc64_addr_sym_match (const struct link_map *l, const ElfW(Sym) *sym, #define DL_ADDR_SYM_MATCH(L, SYM, MATCHSYM, ADDR) \ _dl_ppc64_addr_sym_match (L, SYM, MATCHSYM, ADDR) +#endif + #endif /* ldsodefs.h */ diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S index a7b0a18..b6d82bd 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S @@ -111,6 +111,7 @@ L(parmloop): L(noparms): +#if _CALL_ELF != 2 /* Load the function address and TOC from the function descriptor and store them in the ucontext as NIP and r2. Store the 3rd field of the function descriptor into the ucontext as r11 in case @@ -121,6 +122,12 @@ L(noparms): std r0,(SIGCONTEXT_GP_REGS+(PT_NIP*8))(r3) std r10,(SIGCONTEXT_GP_REGS+(PT_R2*8))(r3) std r9,(SIGCONTEXT_GP_REGS+(PT_R11*8))(r3) +#else + /* In the ELFv2 ABI, the function pointer is already the address. + Store it as NIP and r12 as required by the ABI. */ + std r4,(SIGCONTEXT_GP_REGS+(PT_NIP*8))(r3) + std r4,(SIGCONTEXT_GP_REGS+(PT_R12*8))(r3) +#endif /* If the target function returns we need to do some cleanup. We use a code trick to get the address of our cleanup function into the link -- cgit v1.1