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Diffstat (limited to 'toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc')
| -rw-r--r-- | toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc | 487 |
1 files changed, 487 insertions, 0 deletions
diff --git a/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc new file mode 100644 index 0000000000..2d1ed983dc --- /dev/null +++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc @@ -0,0 +1,487 @@ + +/* libunwind - a platform-independent unwind library + Copyright 2011 Linaro Limited + +This file is part of libunwind. + +Permission is hereby granted, free of charge, to any person obtaining +a copy of this software and associated documentation files (the +"Software"), to deal in the Software without restriction, including +without limitation the rights to use, copy, modify, merge, publish, +distribute, sublicense, and/or sell copies of the Software, and to +permit persons to whom the Software is furnished to do so, subject to +the following conditions: + +The above copyright notice and this permission notice shall be +included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ + +// Copyright (c) 2010 Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + + +// Derived from libunwind, with extensive modifications. + + +#include "common/arm_ex_reader.h" + +#include <assert.h> +#include <stdio.h> + +// This file, in conjunction with arm_ex_to_module.cc, translates +// EXIDX unwind information into the same format that Breakpad uses +// for CFI information. Hence Breakpad's CFI unwinding abilities +// also become usable for EXIDX. +// +// See: "Exception Handling ABI for the ARM Architecture", ARM IHI 0038A +// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf + +// EXIDX data is presented in two parts: +// +// * an index table. This contains two words per routine, +// the first of which identifies the routine, and the second +// of which is a reference to the unwind bytecode. If the +// bytecode is very compact -- 3 bytes or less -- it can be +// stored directly in the second word. +// +// * an area containing the unwind bytecodes. + +// General flow is: ExceptionTableInfo::Start iterates over all +// of the index table entries (pairs). For each entry, it: +// +// * calls ExceptionTableInfo::ExtabEntryExtract to copy the bytecode +// out into an intermediate buffer. + +// * uses ExceptionTableInfo::ExtabEntryDecode to parse the intermediate +// buffer. Each bytecode instruction is bundled into a +// arm_ex_to_module::extab_data structure, and handed to .. +// +// * .. ARMExToModule::ImproveStackFrame, which in turn hands it to +// ARMExToModule::TranslateCmd, and that generates the pseudo-CFI +// records that Breakpad stores. + +#define ARM_EXIDX_CANT_UNWIND 0x00000001 +#define ARM_EXIDX_COMPACT 0x80000000 +#define ARM_EXTBL_OP_FINISH 0xb0 +#define ARM_EXIDX_TABLE_LIMIT (255*4) + +namespace arm_ex_reader { + +using arm_ex_to_module::ARM_EXIDX_CMD_FINISH; +using arm_ex_to_module::ARM_EXIDX_CMD_SUB_FROM_VSP; +using arm_ex_to_module::ARM_EXIDX_CMD_ADD_TO_VSP; +using arm_ex_to_module::ARM_EXIDX_CMD_REG_POP; +using arm_ex_to_module::ARM_EXIDX_CMD_REG_TO_SP; +using arm_ex_to_module::ARM_EXIDX_CMD_VFP_POP; +using arm_ex_to_module::ARM_EXIDX_CMD_WREG_POP; +using arm_ex_to_module::ARM_EXIDX_CMD_WCGR_POP; +using arm_ex_to_module::ARM_EXIDX_CMD_RESERVED; +using arm_ex_to_module::ARM_EXIDX_CMD_REFUSED; +using arm_ex_to_module::exidx_entry; +using arm_ex_to_module::ARM_EXIDX_VFP_SHIFT_16; +using arm_ex_to_module::ARM_EXIDX_VFP_FSTMD; +using google_breakpad::MemoryRange; + + +static void* Prel31ToAddr(const void* addr) { + uint32_t offset32 = *reinterpret_cast<const uint32_t*>(addr); + // sign extend offset32[30:0] to 64 bits -- copy bit 30 to positions + // 63:31 inclusive. + uint64_t offset64 = offset32; + if (offset64 & (1ULL << 30)) + offset64 |= 0xFFFFFFFF80000000ULL; + else + offset64 &= 0x000000007FFFFFFFULL; + return ((char*)addr) + (uintptr_t)offset64; +} + + +// Extract unwind bytecode for the function denoted by |entry| into |buf|, +// and return the number of bytes of |buf| written, along with a code +// indicating the outcome. + +ExceptionTableInfo::ExExtractResult ExceptionTableInfo::ExtabEntryExtract( + const struct exidx_entry* entry, + uint8_t* buf, size_t buf_size, + size_t* buf_used) { + MemoryRange mr_out(buf, buf_size); + + *buf_used = 0; + +# define PUT_BUF_U8(_byte) \ + do { if (!mr_out.Covers(*buf_used, 1)) return ExOutBufOverflow; \ + buf[(*buf_used)++] = (_byte); } while (0) + +# define GET_EX_U32(_lval, _addr, _sec_mr) \ + do { if (!(_sec_mr).Covers(reinterpret_cast<const uint8_t*>(_addr) \ + - (_sec_mr).data(), 4)) \ + return ExInBufOverflow; \ + (_lval) = *(reinterpret_cast<const uint32_t*>(_addr)); } while (0) + +# define GET_EXIDX_U32(_lval, _addr) \ + GET_EX_U32(_lval, _addr, mr_exidx_) +# define GET_EXTAB_U32(_lval, _addr) \ + GET_EX_U32(_lval, _addr, mr_extab_) + + uint32_t data; + GET_EXIDX_U32(data, &entry->data); + + // A function can be marked CANT_UNWIND if (eg) it is known to be + // at the bottom of the stack. + if (data == ARM_EXIDX_CANT_UNWIND) + return ExCantUnwind; + + uint32_t pers; // personality number + uint32_t extra; // number of extra data words required + uint32_t extra_allowed; // number of extra data words allowed + uint32_t* extbl_data; // the handler entry, if not inlined + + if (data & ARM_EXIDX_COMPACT) { + // The handler table entry has been inlined into the index table entry. + // In this case it can only be an ARM-defined compact model, since + // bit 31 is 1. Only personalities 0, 1 and 2 are defined for the + // ARM compact model, but 1 and 2 are "Long format" and may require + // extra data words. Hence the allowable personalities here are: + // personality 0, in which case 'extra' has no meaning + // personality 1, with zero extra words + // personality 2, with zero extra words + extbl_data = NULL; + pers = (data >> 24) & 0x0F; + extra = (data >> 16) & 0xFF; + extra_allowed = 0; + } + else { + // The index table entry is a pointer to the handler entry. Note + // that Prel31ToAddr will read the given address, but we already + // range-checked above. + extbl_data = reinterpret_cast<uint32_t*>(Prel31ToAddr(&entry->data)); + GET_EXTAB_U32(data, extbl_data); + if (!(data & ARM_EXIDX_COMPACT)) { + // This denotes a "generic model" handler. That will involve + // executing arbitary machine code, which is something we + // can't represent here; hence reject it. + return ExCantRepresent; + } + // So we have a compact model representation. Again, 3 possible + // personalities, but this time up to 255 allowable extra words. + pers = (data >> 24) & 0x0F; + extra = (data >> 16) & 0xFF; + extra_allowed = 255; + extbl_data++; + } + + // Now look at the the handler table entry. The first word is + // |data| and subsequent words start at |*extbl_data|. The number + // of extra words to use is |extra|, provided that the personality + // allows extra words. Even if it does, none may be available -- + // extra_allowed is the maximum number of extra words allowed. */ + if (pers == 0) { + // "Su16" in the documentation -- 3 unwinding insn bytes + // |extra| has no meaning here; instead that byte is an unwind-info byte + PUT_BUF_U8(data >> 16); + PUT_BUF_U8(data >> 8); + PUT_BUF_U8(data); + } + else if ((pers == 1 || pers == 2) && extra <= extra_allowed) { + // "Lu16" or "Lu32" respectively -- 2 unwinding insn bytes, + // and up to 255 extra words. + PUT_BUF_U8(data >> 8); + PUT_BUF_U8(data); + for (uint32_t j = 0; j < extra; j++) { + GET_EXTAB_U32(data, extbl_data); + extbl_data++; + PUT_BUF_U8(data >> 24); + PUT_BUF_U8(data >> 16); + PUT_BUF_U8(data >> 8); + PUT_BUF_U8(data >> 0); + } + } + else { + // The entry is invalid. + return ExInvalid; + } + + // Make sure the entry is terminated with "FINISH" + if (*buf_used > 0 && buf[(*buf_used) - 1] != ARM_EXTBL_OP_FINISH) + PUT_BUF_U8(ARM_EXTBL_OP_FINISH); + + return ExSuccess; + +# undef GET_EXTAB_U32 +# undef GET_EXIDX_U32 +# undef GET_U32 +# undef PUT_BUF_U8 +} + + +// Take the unwind information extracted by ExtabEntryExtract +// and parse it into frame-unwind instructions. These are as +// specified in "Table 4, ARM-defined frame-unwinding instructions" +// in the specification document detailed in comments at the top +// of this file. +// +// This reads from |buf[0, +data_size)|. It checks for overruns of +// the input buffer and returns a negative value if that happens, or +// for any other failure cases. It returns zero in case of success. +int ExceptionTableInfo::ExtabEntryDecode(const uint8_t* buf, size_t buf_size) { + if (buf == NULL || buf_size == 0) + return -1; + + MemoryRange mr_in(buf, buf_size); + const uint8_t* buf_initially = buf; + +# define GET_BUF_U8(_lval) \ + do { if (!mr_in.Covers(buf - buf_initially, 1)) return -1; \ + (_lval) = *(buf++); } while (0) + + const uint8_t* end = buf + buf_size; + + while (buf < end) { + struct arm_ex_to_module::extab_data edata; + memset(&edata, 0, sizeof(edata)); + + uint8_t op; + GET_BUF_U8(op); + if ((op & 0xc0) == 0x00) { + // vsp = vsp + (xxxxxx << 2) + 4 + edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP; + edata.data = (((int)op & 0x3f) << 2) + 4; + } else if ((op & 0xc0) == 0x40) { + // vsp = vsp - (xxxxxx << 2) - 4 + edata.cmd = ARM_EXIDX_CMD_SUB_FROM_VSP; + edata.data = (((int)op & 0x3f) << 2) + 4; + } else if ((op & 0xf0) == 0x80) { + uint8_t op2; + GET_BUF_U8(op2); + if (op == 0x80 && op2 == 0x00) { + // Refuse to unwind + edata.cmd = ARM_EXIDX_CMD_REFUSED; + } else { + // Pop up to 12 integer registers under masks {r15-r12},{r11-r4} + edata.cmd = ARM_EXIDX_CMD_REG_POP; + edata.data = ((op & 0xf) << 8) | op2; + edata.data = edata.data << 4; + } + } else if ((op & 0xf0) == 0x90) { + if (op == 0x9d || op == 0x9f) { + // 9d: Reserved as prefix for ARM register to register moves + // 9f: Reserved as perfix for Intel Wireless MMX reg to reg moves + edata.cmd = ARM_EXIDX_CMD_RESERVED; + } else { + // Set vsp = r[nnnn] + edata.cmd = ARM_EXIDX_CMD_REG_TO_SP; + edata.data = op & 0x0f; + } + } else if ((op & 0xf0) == 0xa0) { + // Pop r4 to r[4+nnn], or + // Pop r4 to r[4+nnn] and r14 or + unsigned end = (op & 0x07); + edata.data = (1 << (end + 1)) - 1; + edata.data = edata.data << 4; + if (op & 0x08) edata.data |= 1 << 14; + edata.cmd = ARM_EXIDX_CMD_REG_POP; + } else if (op == ARM_EXTBL_OP_FINISH) { + // Finish + edata.cmd = ARM_EXIDX_CMD_FINISH; + buf = end; + } else if (op == 0xb1) { + uint8_t op2; + GET_BUF_U8(op2); + if (op2 == 0 || (op2 & 0xf0)) { + // Spare + edata.cmd = ARM_EXIDX_CMD_RESERVED; + } else { + // Pop integer registers under mask {r3,r2,r1,r0} + edata.cmd = ARM_EXIDX_CMD_REG_POP; + edata.data = op2 & 0x0f; + } + } else if (op == 0xb2) { + // vsp = vsp + 0x204 + (uleb128 << 2) + uint64_t offset = 0; + uint8_t byte, shift = 0; + do { + GET_BUF_U8(byte); + offset |= (byte & 0x7f) << shift; + shift += 7; + } while ((byte & 0x80) && buf < end); + edata.data = offset * 4 + 0x204; + edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP; + } else if (op == 0xb3 || op == 0xc8 || op == 0xc9) { + // b3: Pop VFP regs D[ssss] to D[ssss+cccc], FSTMFDX-ishly + // c8: Pop VFP regs D[16+ssss] to D[16+ssss+cccc], FSTMFDD-ishly + // c9: Pop VFP regs D[ssss] to D[ssss+cccc], FSTMFDD-ishly + edata.cmd = ARM_EXIDX_CMD_VFP_POP; + GET_BUF_U8(edata.data); + if (op == 0xc8) edata.data |= ARM_EXIDX_VFP_SHIFT_16; + if (op != 0xb3) edata.data |= ARM_EXIDX_VFP_FSTMD; + } else if ((op & 0xf8) == 0xb8 || (op & 0xf8) == 0xd0) { + // b8: Pop VFP regs D[8] to D[8+nnn], FSTMFDX-ishly + // d0: Pop VFP regs D[8] to D[8+nnn], FSTMFDD-ishly + edata.cmd = ARM_EXIDX_CMD_VFP_POP; + edata.data = 0x80 | (op & 0x07); + if ((op & 0xf8) == 0xd0) edata.data |= ARM_EXIDX_VFP_FSTMD; + } else if (op >= 0xc0 && op <= 0xc5) { + // Intel Wireless MMX pop wR[10]-wr[10+nnn], nnn != 6,7 + edata.cmd = ARM_EXIDX_CMD_WREG_POP; + edata.data = 0xa0 | (op & 0x07); + } else if (op == 0xc6) { + // Intel Wireless MMX pop wR[ssss] to wR[ssss+cccc] + edata.cmd = ARM_EXIDX_CMD_WREG_POP; + GET_BUF_U8(edata.data); + } else if (op == 0xc7) { + uint8_t op2; + GET_BUF_U8(op2); + if (op2 == 0 || (op2 & 0xf0)) { + // Spare + edata.cmd = ARM_EXIDX_CMD_RESERVED; + } else { + // Intel Wireless MMX pop wCGR registers under mask {wCGR3,2,1,0} + edata.cmd = ARM_EXIDX_CMD_WCGR_POP; + edata.data = op2 & 0x0f; + } + } else { + // Spare + edata.cmd = ARM_EXIDX_CMD_RESERVED; + } + + int ret = handler_->ImproveStackFrame(&edata); + if (ret < 0) + return ret; + } + return 0; + +# undef GET_BUF_U8 +} + +void ExceptionTableInfo::Start() { + const struct exidx_entry* start + = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data()); + const struct exidx_entry* end + = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data() + + mr_exidx_.length()); + + // Iterate over each of the EXIDX entries (pairs of 32-bit words). + // These occupy the entire .exidx section. + for (const struct exidx_entry* entry = start; entry < end; ++entry) { + // Figure out the code address range that this table entry is + // associated with. + uint32_t addr = (reinterpret_cast<char*>(Prel31ToAddr(&entry->addr)) + - mapping_addr_ + loading_addr_) & 0x7fffffff; + uint32_t next_addr; + if (entry < end - 1) { + next_addr = (reinterpret_cast<char*>(Prel31ToAddr(&((entry + 1)->addr))) + - mapping_addr_ + loading_addr_) & 0x7fffffff; + } else { + // This is the last EXIDX entry in the sequence, so we don't + // have an address for the start of the next function, to limit + // this one. Instead use the address of the last byte of the + // text section associated with this .exidx section, that we + // have been given. So as to avoid junking up the CFI unwind + // tables with absurdly large address ranges in the case where + // text_last_svma_ is wrong, only use the value if it is nonzero + // and within one page of |addr|. Otherwise assume a length of 1. + // + // In some cases, gcc has been observed to finish the exidx + // section with an entry of length 1 marked CANT_UNWIND, + // presumably exactly for the purpose of giving a definite + // length for the last real entry, without having to look at + // text segment boundaries. + bool plausible = false; + next_addr = addr + 1; + if (text_last_svma_ != 0) { + uint32_t maybe_next_addr = text_last_svma_ + 1; + if (maybe_next_addr > addr && maybe_next_addr - addr <= 4096) { + next_addr = maybe_next_addr; + plausible = true; + } + } + if (!plausible) { + fprintf(stderr, "ExceptionTableInfo: implausible EXIDX last entry size " + "%d, using 1 instead.", (int32_t)(text_last_svma_ - addr)); + } + } + + // Extract the unwind info into |buf|. This might fail for + // various reasons. It involves reading both the .exidx and + // .extab sections. All accesses to those sections are + // bounds-checked. + uint8_t buf[ARM_EXIDX_TABLE_LIMIT]; + size_t buf_used = 0; + ExExtractResult res = ExtabEntryExtract(entry, buf, sizeof(buf), &buf_used); + if (res != ExSuccess) { + // Couldn't extract the unwind info, for some reason. Move on. + switch (res) { + case ExInBufOverflow: + fprintf(stderr, "ExtabEntryExtract: .exidx/.extab section overrun"); + break; + case ExOutBufOverflow: + fprintf(stderr, "ExtabEntryExtract: bytecode buffer overflow"); + break; + case ExCantUnwind: + fprintf(stderr, "ExtabEntryExtract: function is marked CANT_UNWIND"); + break; + case ExCantRepresent: + fprintf(stderr, "ExtabEntryExtract: bytecode can't be represented"); + break; + case ExInvalid: + fprintf(stderr, "ExtabEntryExtract: index table entry is invalid"); + break; + default: + fprintf(stderr, "ExtabEntryExtract: unknown error: %d", (int)res); + break; + } + continue; + } + + // Finally, work through the unwind instructions in |buf| and + // create CFI entries that Breakpad can use. This can also fail. + // First, add a new stack frame entry, into which ExtabEntryDecode + // will write the CFI entries. + if (!handler_->HasStackFrame(addr, next_addr - addr)) { + handler_->AddStackFrame(addr, next_addr - addr); + int ret = ExtabEntryDecode(buf, buf_used); + if (ret < 0) { + handler_->DeleteStackFrame(); + fprintf(stderr, "ExtabEntryDecode: failed with error code: %d", ret); + continue; + } + handler_->SubmitStackFrame(); + } + + } /* iterating over .exidx */ +} + +} // namespace arm_ex_reader |