Skip to content

Commit

Permalink
Promote nameless lambda used by dl_iterate_phdr to named function.
Browse files Browse the repository at this point in the history 
Summary:
This cleans up control flow inside findUnwindSections, and will make
it easier to replace this code in a following patch. Also, expose the
data structure to allow use by a future replacment function.

Reviewers: mstorsjo, miyuki

Subscribers: krytarowski, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D75637
  • Loading branch information
@Sterling-Augustine
Sterling-Augustine committed Mar 5, 2020
1 parent c7b6fa8 commit 470f995
Showing 1 changed file with 122 additions and 103 deletions.
225 changes: 122 additions & 103 deletions libunwind/src/AddressSpace.hpp
View file
Expand Up @@ -392,6 +392,127 @@ LocalAddressSpace::getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
return result;
}

#ifdef __APPLE__
#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
#elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
#elif defined(_LIBUNWIND_ARM_EHABI) && defined(__BIONIC__)
// Code inside findUnwindSections handles all these cases.
//
// Although the above ifdef chain is ugly, there doesn't seem to be a cleaner
// way to handle it. The generalized boolean expression is:
//
// A OR (B AND C) OR (D AND C) OR (B AND E) OR (F AND E) OR (D AND G)
//
// Running it through various boolean expression simplifiers gives expressions
// that don't help at all.
#elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)

struct _LIBUNWIND_HIDDEN dl_iterate_cb_data {
LocalAddressSpace *addressSpace;
UnwindInfoSections *sects;
uintptr_t targetAddr;
};

int findUnwindSectionsByPhdr(struct dl_phdr_info *pinfo, size_t, void *data) {
auto cbdata = static_cast<dl_iterate_cb_data *>(data);
bool found_obj = false;
bool found_hdr = false;

assert(cbdata);
assert(cbdata->sects);

if (cbdata->targetAddr < pinfo->dlpi_addr) {
return false;
}

#if !defined(Elf_Half)
typedef ElfW(Half) Elf_Half;
#endif
#if !defined(Elf_Phdr)
typedef ElfW(Phdr) Elf_Phdr;
#endif
#if !defined(Elf_Addr)
typedef ElfW(Addr) Elf_Addr;
#endif

Elf_Addr image_base = pinfo->dlpi_addr;

#if defined(__ANDROID__) && __ANDROID_API__ < 18
if (image_base == 0) {
// Normally, an image base of 0 indicates a non-PIE executable. On
// versions of Android prior to API 18, the dynamic linker reported a
// dlpi_addr of 0 for PIE executables. Compute the true image base
// using the PT_PHDR segment.
// See https://github.com/android/ndk/issues/505.
for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
if (phdr->p_type == PT_PHDR) {
image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
phdr->p_vaddr;
break;
}
}
}
#endif

#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
#if !defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
#error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
#endif
size_t object_length;

for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
if (phdr->p_type == PT_LOAD) {
uintptr_t begin = image_base + phdr->p_vaddr;
uintptr_t end = begin + phdr->p_memsz;
if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
cbdata->sects->dso_base = begin;
object_length = phdr->p_memsz;
found_obj = true;
}
} else if (phdr->p_type == PT_GNU_EH_FRAME) {
EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
*cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
hdrInfo);
if (found_hdr)
cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
}
}

if (found_obj && found_hdr) {
cbdata->sects->dwarf_section_length = object_length;
return true;
} else {
return false;
}
#else // defined(_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_LOAD) {
uintptr_t begin = image_base + phdr->p_vaddr;
uintptr_t end = begin + phdr->p_memsz;
if (cbdata->targetAddr >= begin && cbdata->targetAddr < end)
found_obj = true;
} else if (phdr->p_type == PT_ARM_EXIDX) {
uintptr_t exidx_start = image_base + phdr->p_vaddr;
cbdata->sects->arm_section = exidx_start;
cbdata->sects->arm_section_length = phdr->p_memsz;
found_hdr = true;
}
}
return found_obj && found_hdr;
#endif
}
#endif // defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)


inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
UnwindInfoSections &info) {
#ifdef __APPLE__
Expand Down Expand Up @@ -483,110 +604,8 @@ inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
if (info.arm_section && info.arm_section_length)
return true;
#elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
struct dl_iterate_cb_data {
LocalAddressSpace *addressSpace;
UnwindInfoSections *sects;
uintptr_t targetAddr;
};

dl_iterate_cb_data cb_data = {this, &info, targetAddr};
int found = dl_iterate_phdr(
[](struct dl_phdr_info *pinfo, size_t, void *data) -> int {
auto cbdata = static_cast<dl_iterate_cb_data *>(data);
bool found_obj = false;
bool found_hdr = false;

assert(cbdata);
assert(cbdata->sects);

if (cbdata->targetAddr < pinfo->dlpi_addr) {
return false;
}

#if !defined(Elf_Half)
typedef ElfW(Half) Elf_Half;
#endif
#if !defined(Elf_Phdr)
typedef ElfW(Phdr) Elf_Phdr;
#endif
#if !defined(Elf_Addr)
typedef ElfW(Addr) Elf_Addr;
#endif

Elf_Addr image_base = pinfo->dlpi_addr;

#if defined(__ANDROID__) && __ANDROID_API__ < 18
if (image_base == 0) {
// Normally, an image base of 0 indicates a non-PIE executable. On
// versions of Android prior to API 18, the dynamic linker reported a
// dlpi_addr of 0 for PIE executables. Compute the true image base
// using the PT_PHDR segment.
// See https://github.com/android/ndk/issues/505.
for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
if (phdr->p_type == PT_PHDR) {
image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
phdr->p_vaddr;
break;
}
}
}
#endif

#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
#if !defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
#error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
#endif
size_t object_length;

for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
if (phdr->p_type == PT_LOAD) {
uintptr_t begin = image_base + phdr->p_vaddr;
uintptr_t end = begin + phdr->p_memsz;
if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
cbdata->sects->dso_base = begin;
object_length = phdr->p_memsz;
found_obj = true;
}
} else if (phdr->p_type == PT_GNU_EH_FRAME) {
EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
*cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
hdrInfo);
if (found_hdr)
cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
}
}

if (found_obj && found_hdr) {
cbdata->sects->dwarf_section_length = object_length;
return true;
} else {
return false;
}
#else // defined(_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_LOAD) {
uintptr_t begin = image_base + phdr->p_vaddr;
uintptr_t end = begin + phdr->p_memsz;
if (cbdata->targetAddr >= begin && cbdata->targetAddr < end)
found_obj = true;
} else if (phdr->p_type == PT_ARM_EXIDX) {
uintptr_t exidx_start = image_base + phdr->p_vaddr;
cbdata->sects->arm_section = exidx_start;
cbdata->sects->arm_section_length = phdr->p_memsz;
found_hdr = true;
}
}
return found_obj && found_hdr;
#endif
},
&cb_data);
int found = dl_iterate_phdr(findUnwindSectionsByPhdr, &cb_data);
return static_cast<bool>(found);
#endif

Expand Down

0 comments on commit 470f995

Please sign in to comment.