Author: ed Date: Thu Feb 23 02:05:58 2017 New Revision: 295944 URL: http://llvm.org/viewvc/llvm-project?rev=295944&view=rev Log: Drop the dependency on dl_unwind_find_exidx().
While porting libunwind over to CloudABI for ARMv6, I observed that this source file doesn't build, as it depends on dl_unwind_find_exidx(), which CloudABI's C library was lacking. After I added that function, I still needed to patch up libunwind to define _Unwind_Ptr. Taking a step back, I wonder why we need to make use of this function anyway. The unwinder already has some nice code to use dl_iterate_phdr() to scan for a PT_GNU_EH_FRAME header. The dl_unwind_find_exidx() does the same thing, except matching PT_ARM_EXIDX instead. We could also do that ourselves. This change gets rid of the dl_unwind_find_exidx() call and extends the dl_iterate_phdr() loop. In addition to making the code a bit shorter, it has the advantage of getting rid of some of those OS-specific #ifdefs. This now means that if an operating system only provides dl_iterate_phdr(), it gets support for unwinding on all architectures. There is no need to add more stuff, just to get ARMv6 support. Differential Revision: https://reviews.llvm.org/D28082 Modified: libunwind/trunk/src/AddressSpace.hpp Modified: libunwind/trunk/src/AddressSpace.hpp URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/AddressSpace.hpp?rev=295944&r1=295943&r2=295944&view=diff ============================================================================== --- libunwind/trunk/src/AddressSpace.hpp (original) +++ libunwind/trunk/src/AddressSpace.hpp Thu Feb 23 02:05:58 2017 @@ -35,29 +35,17 @@ namespace libunwind { #include "Registers.hpp" #if _LIBUNWIND_ARM_EHABI -#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) - -typedef void *_Unwind_Ptr; - -#elif defined(__linux__) - -typedef long unsigned int *_Unwind_Ptr; -extern "C" _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr addr, int *len); - -// Emulate the BSD dl_unwind_find_exidx API when on a GNU libdl system. -#define dl_unwind_find_exidx __gnu_Unwind_Find_exidx - -#elif !defined(_LIBUNWIND_IS_BAREMETAL) -#include <link.h> -#else // !defined(_LIBUNWIND_IS_BAREMETAL) -// When statically linked on bare-metal, the symbols for the EH table are looked -// up without going through the dynamic loader. struct EHTEntry { uint32_t functionOffset; uint32_t unwindOpcodes; }; +#if defined(_LIBUNWIND_IS_BAREMETAL) +// When statically linked on bare-metal, the symbols for the EH table are looked +// up without going through the dynamic loader. extern EHTEntry __exidx_start; extern EHTEntry __exidx_end; +#else +#include <link.h> #endif // !defined(_LIBUNWIND_IS_BAREMETAL) #endif // _LIBUNWIND_ARM_EHABI @@ -368,23 +356,15 @@ inline bool LocalAddressSpace::findUnwin info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length; return true; } -#elif _LIBUNWIND_ARM_EHABI - #ifdef _LIBUNWIND_IS_BAREMETAL +#elif _LIBUNWIND_ARM_EHABI && defined(_LIBUNWIND_IS_BAREMETAL) // Bare metal is statically linked, so no need to ask the dynamic loader info.arm_section = (uintptr_t)(&__exidx_start); info.arm_section_length = (uintptr_t)(&__exidx_end - &__exidx_start); - #else - int length = 0; - info.arm_section = (uintptr_t) dl_unwind_find_exidx( - (_Unwind_Ptr) targetAddr, &length); - info.arm_section_length = (uintptr_t)length; - #endif _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %X length %x", info.arm_section, info.arm_section_length); if (info.arm_section && info.arm_section_length) return true; -#elif _LIBUNWIND_SUPPORT_DWARF_UNWIND -#if _LIBUNWIND_SUPPORT_DWARF_INDEX +#elif _LIBUNWIND_ARM_EHABI || _LIBUNWIND_SUPPORT_DWARF_UNWIND struct dl_iterate_cb_data { LocalAddressSpace *addressSpace; UnwindInfoSections *sects; @@ -395,9 +375,6 @@ inline bool LocalAddressSpace::findUnwin int found = dl_iterate_phdr( [](struct dl_phdr_info *pinfo, size_t, void *data) -> int { auto cbdata = static_cast<dl_iterate_cb_data *>(data); - size_t object_length; - bool found_obj = false; - bool found_hdr = false; assert(cbdata); assert(cbdata->sects); @@ -413,6 +390,14 @@ inline bool LocalAddressSpace::findUnwin typedef ElfW(Phdr) Elf_Phdr; #endif + #if _LIBUNWIND_SUPPORT_DWARF_UNWIND + #if !_LIBUNWIND_SUPPORT_DWARF_INDEX + #error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform." + #endif + size_t object_length; + bool found_obj = false; + bool found_hdr = false; + for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) { const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i]; if (phdr->p_type == PT_LOAD) { @@ -442,12 +427,22 @@ inline bool LocalAddressSpace::findUnwin } else { return false; } + #else // _LIBUNWIND_ARM_EHABI + for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) { + const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i]; + if (phdr->p_type == PT_ARM_EXIDX) { + uintptr_t exidx_start = pinfo->dlpi_addr + phdr->p_vaddr; + cbdata->sects->arm_section = exidx_start; + cbdata->sects->arm_section_length = phdr->p_memsz / + sizeof(EHTEntry); + return true; + } + } + return false; + #endif }, &cb_data); return static_cast<bool>(found); -#else -#error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform." -#endif #endif return false; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits