diff options
Diffstat (limited to 'src/client')
| -rw-r--r-- | src/client/linux/microdump_writer/microdump_writer.cc | 2 | ||||
| -rw-r--r-- | src/client/linux/minidump_writer/linux_dumper.cc | 125 | ||||
| -rw-r--r-- | src/client/linux/minidump_writer/linux_dumper.h | 65 | ||||
| -rw-r--r-- | src/client/linux/minidump_writer/minidump_writer.cc | 2 |
4 files changed, 192 insertions, 2 deletions
diff --git a/src/client/linux/microdump_writer/microdump_writer.cc b/src/client/linux/microdump_writer/microdump_writer.cc index f45925fe..247387e2 100644 --- a/src/client/linux/microdump_writer/microdump_writer.cc +++ b/src/client/linux/microdump_writer/microdump_writer.cc @@ -86,7 +86,7 @@ class MicrodumpWriter { // try to not crash. if (!dumper_->Init() || !log_line_) return false; - return dumper_->ThreadsSuspend(); + return dumper_->ThreadsSuspend() && dumper_->LateInit(); } bool Dump() { diff --git a/src/client/linux/minidump_writer/linux_dumper.cc b/src/client/linux/minidump_writer/linux_dumper.cc index ebb008d6..00d18189 100644 --- a/src/client/linux/minidump_writer/linux_dumper.cc +++ b/src/client/linux/minidump_writer/linux_dumper.cc @@ -52,6 +52,22 @@ #include "common/linux/safe_readlink.h" #include "third_party/lss/linux_syscall_support.h" +#if defined(__ANDROID__) + +// Android packed relocations definitions are not yet available from the +// NDK header files, so we have to provide them manually here. +#ifndef DT_LOOS +#define DT_LOOS 0x6000000d +#endif +#ifndef DT_ANDROID_REL +static const int DT_ANDROID_REL = DT_LOOS + 2; +#endif +#ifndef DT_ANDROID_RELA +static const int DT_ANDROID_RELA = DT_LOOS + 4; +#endif + +#endif // __ANDROID __ + static const char kMappedFileUnsafePrefix[] = "/dev/"; static const char kDeletedSuffix[] = " (deleted)"; static const char kReservedFlags[] = " ---p"; @@ -92,6 +108,13 @@ bool LinuxDumper::Init() { return ReadAuxv() && EnumerateThreads() && EnumerateMappings(); } +bool LinuxDumper::LateInit() { +#if defined(__ANDROID__) + LatePostprocessMappings(); +#endif + return true; +} + bool LinuxDumper::ElfFileIdentifierForMapping(const MappingInfo& mapping, bool member, @@ -395,6 +418,108 @@ bool LinuxDumper::EnumerateMappings() { return !mappings_.empty(); } +#if defined(__ANDROID__) + +bool LinuxDumper::GetLoadedElfHeader(uintptr_t start_addr, ElfW(Ehdr)* ehdr) { + CopyFromProcess(ehdr, pid_, + reinterpret_cast<const void*>(start_addr), + sizeof(*ehdr)); + return my_memcmp(&ehdr->e_ident, ELFMAG, SELFMAG) == 0; +} + +void LinuxDumper::ParseLoadedElfProgramHeaders(ElfW(Ehdr)* ehdr, + uintptr_t start_addr, + uintptr_t* min_vaddr_ptr, + uintptr_t* dyn_vaddr_ptr, + size_t* dyn_count_ptr) { + uintptr_t phdr_addr = start_addr + ehdr->e_phoff; + + const uintptr_t max_addr = UINTPTR_MAX; + uintptr_t min_vaddr = max_addr; + uintptr_t dyn_vaddr = 0; + size_t dyn_count = 0; + + for (size_t i = 0; i < ehdr->e_phnum; ++i) { + ElfW(Phdr) phdr; + CopyFromProcess(&phdr, pid_, + reinterpret_cast<const void*>(phdr_addr), + sizeof(phdr)); + if (phdr.p_type == PT_LOAD && phdr.p_vaddr < min_vaddr) { + min_vaddr = phdr.p_vaddr; + } + if (phdr.p_type == PT_DYNAMIC) { + dyn_vaddr = phdr.p_vaddr; + dyn_count = phdr.p_memsz / sizeof(ElfW(Dyn)); + } + phdr_addr += sizeof(phdr); + } + + *min_vaddr_ptr = min_vaddr; + *dyn_vaddr_ptr = dyn_vaddr; + *dyn_count_ptr = dyn_count; +} + +bool LinuxDumper::HasAndroidPackedRelocations(uintptr_t load_bias, + uintptr_t dyn_vaddr, + size_t dyn_count) { + uintptr_t dyn_addr = load_bias + dyn_vaddr; + for (size_t i = 0; i < dyn_count; ++i) { + ElfW(Dyn) dyn; + CopyFromProcess(&dyn, pid_, + reinterpret_cast<const void*>(dyn_addr), + sizeof(dyn)); + if (dyn.d_tag == DT_ANDROID_REL || dyn.d_tag == DT_ANDROID_RELA) { + return true; + } + dyn_addr += sizeof(dyn); + } + return false; +} + +uintptr_t LinuxDumper::GetEffectiveLoadBias(ElfW(Ehdr)* ehdr, + uintptr_t start_addr) { + uintptr_t min_vaddr = 0; + uintptr_t dyn_vaddr = 0; + size_t dyn_count = 0; + ParseLoadedElfProgramHeaders(ehdr, start_addr, + &min_vaddr, &dyn_vaddr, &dyn_count); + // If |min_vaddr| is non-zero and we find Android packed relocation tags, + // return the effective load bias. + if (min_vaddr != 0) { + const uintptr_t load_bias = start_addr - min_vaddr; + if (HasAndroidPackedRelocations(load_bias, dyn_vaddr, dyn_count)) { + return load_bias; + } + } + // Either |min_vaddr| is zero, or it is non-zero but we did not find the + // expected Android packed relocations tags. + return start_addr; +} + +void LinuxDumper::LatePostprocessMappings() { + for (size_t i = 0; i < mappings_.size(); ++i) { + // Only consider exec mappings that indicate a file path was mapped, and + // where the ELF header indicates a mapped shared library. + MappingInfo* mapping = mappings_[i]; + if (!(mapping->exec && mapping->name[0] == '/')) { + continue; + } + ElfW(Ehdr) ehdr; + if (!GetLoadedElfHeader(mapping->start_addr, &ehdr)) { + continue; + } + if (ehdr.e_type == ET_DYN) { + // Compute the effective load bias for this mapped library, and update + // the mapping to hold that rather than |start_addr|. Where the library + // does not contain Android packed relocations, GetEffectiveLoadBias() + // returns |start_addr| and the mapping entry is not changed. + mapping->start_addr = GetEffectiveLoadBias(&ehdr, mapping->start_addr); + } + } +} + +#endif // __ANDROID__ + // Get information about the stack, given the stack pointer. We don't try to // walk the stack since we might not have all the information needed to do // unwind. So we just grab, up to, 32k of stack. diff --git a/src/client/linux/minidump_writer/linux_dumper.h b/src/client/linux/minidump_writer/linux_dumper.h index 87dfadb4..6a3a100f 100644 --- a/src/client/linux/minidump_writer/linux_dumper.h +++ b/src/client/linux/minidump_writer/linux_dumper.h @@ -39,6 +39,9 @@ #define CLIENT_LINUX_MINIDUMP_WRITER_LINUX_DUMPER_H_ #include <elf.h> +#if defined(__ANDROID__) +#include <link.h> +#endif #include <linux/limits.h> #include <stdint.h> #include <sys/types.h> @@ -76,6 +79,12 @@ class LinuxDumper { // Parse the data for |threads| and |mappings|. virtual bool Init(); + // Take any actions that could not be taken in Init(). LateInit() is + // called after all other caller's initialization is complete, and in + // particular after it has called ThreadsSuspend(), so that ptrace is + // available. + virtual bool LateInit(); + // Return true if the dumper performs a post-mortem dump. virtual bool IsPostMortem() const = 0; @@ -182,6 +191,62 @@ class LinuxDumper { // Info from /proc/<pid>/auxv wasteful_vector<elf_aux_val_t> auxv_; + +#if defined(__ANDROID__) + private: + // Android M and later support packed ELF relocations in shared libraries. + // Packing relocations changes the vaddr of the LOAD segments, such that + // the effective load bias is no longer the same as the start address of + // the memory mapping containing the executable parts of the library. The + // packing is applied to the stripped library run on the target, but not to + // any other library, and in particular not to the library used to generate + // breakpad symbols. As a result, we need to adjust the |start_addr| for + // any mapping that results from a shared library that contains Android + // packed relocations, so that it properly represents the effective library + // load bias. The following functions support this adjustment. + + // Check that a given mapping at |start_addr| is for an ELF shared library. + // If it is, place the ELF header in |ehdr| and return true. + // The first LOAD segment in an ELF shared library has offset zero, so the + // ELF file header is at the start of this map entry, and in already mapped + // memory. + bool GetLoadedElfHeader(uintptr_t start_addr, ElfW(Ehdr)* ehdr); + + // For the ELF file mapped at |start_addr|, iterate ELF program headers to + // find the min vaddr of all program header LOAD segments, the vaddr for + // the DYNAMIC segment, and a count of DYNAMIC entries. Return values in + // |min_vaddr_ptr|, |dyn_vaddr_ptr|, and |dyn_count_ptr|. + // The program header table is also in already mapped memory. + void ParseLoadedElfProgramHeaders(ElfW(Ehdr)* ehdr, + uintptr_t start_addr, + uintptr_t* min_vaddr_ptr, + uintptr_t* dyn_vaddr_ptr, + size_t* dyn_count_ptr); + + // Search the DYNAMIC tags for the ELF file with the given |load_bias|, and + // return true if the tags indicate that the file contains Android packed + // relocations. Dynamic tags are found at |dyn_vaddr| past the |load_bias|. + bool HasAndroidPackedRelocations(uintptr_t load_bias, + uintptr_t dyn_vaddr, + size_t dyn_count); + + // If the ELF file mapped at |start_addr| contained Android packed + // relocations, return the load bias that the system linker (or Chromium + // crazy linker) will have used. If the file did not contain Android + // packed relocations, returns |start_addr|, indicating that no adjustment + // is necessary. + // The effective load bias is |start_addr| adjusted downwards by the + // min vaddr in the library LOAD segments. + uintptr_t GetEffectiveLoadBias(ElfW(Ehdr)* ehdr, uintptr_t start_addr); + + // Called from LateInit(). Iterates |mappings_| and rewrites the |start_addr| + // field of any that represent ELF shared libraries with Android packed + // relocations, so that |start_addr| is the load bias that the system linker + // (or Chromium crazy linker) used. This value matches the addresses produced + // when the non-relocation-packed library is used for breakpad symbol + // generation. + void LatePostprocessMappings(); +#endif // __ANDROID__ }; } // namespace google_breakpad diff --git a/src/client/linux/minidump_writer/minidump_writer.cc b/src/client/linux/minidump_writer/minidump_writer.cc index 0414bb72..9c1db99b 100644 --- a/src/client/linux/minidump_writer/minidump_writer.cc +++ b/src/client/linux/minidump_writer/minidump_writer.cc @@ -154,7 +154,7 @@ class MinidumpWriter { else if (!minidump_writer_.Open(path_)) return false; - return dumper_->ThreadsSuspend(); + return dumper_->ThreadsSuspend() && dumper_->LateInit(); } ~MinidumpWriter() { |