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Resurrect deps/patches/llvm-libunwind-prologue-epilogue.patch #45175

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Resurrect deps/patches/llvm-libunwind-prologue-epilogue.patch #45175

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183 changes: 183 additions & 0 deletions deps/patches/llvm-libunwind-prologue-epilogue.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,183 @@
An updated version of this libosxunwind commit:

commit ca57a5b60de4cd1daa42ed2e5d1d4aa3e96a09d1
Author: Keno Fischer <[email protected]>
Date: Mon Aug 26 15:28:08 2013 -0400

Add support for unwinding during prologue/epilogue

---
diff --git a/libunwind/src/CompactUnwinder.hpp b/libunwind/src/CompactUnwinder.hpp
index 1c3175dff50a..78a658ccbc27 100644
--- a/libunwind/src/CompactUnwinder.hpp
+++ b/libunwind/src/CompactUnwinder.hpp
@@ -310,6 +310,50 @@ int CompactUnwinder_x86_64<A>::stepWithCompactEncodingRBPFrame(
uint32_t savedRegistersLocations =
EXTRACT_BITS(compactEncoding, UNWIND_X86_64_RBP_FRAME_REGISTERS);

+ // If we have not stored EBP yet
+ if (functionStart == registers.getIP()) {
+ uint64_t rsp = registers.getSP();
+ // old esp is ebp less return address
+ registers.setSP(rsp+8);
+ // pop return address into eip
+ registers.setIP(addressSpace.get64(rsp));
+
+ return UNW_STEP_SUCCESS;
+ } else if (functionStart + 1 == registers.getIP()) {
+ uint64_t rsp = registers.getSP();
+ // old esp is ebp less return address
+ registers.setSP(rsp + 16);
+ // pop return address into eip
+ registers.setIP(addressSpace.get64(rsp + 8));
+
+ return UNW_STEP_SUCCESS;
+ }
+
+ // If we're about to return, we've already popped the base pointer
+ uint8_t b = addressSpace.get8(registers.getIP());
+
+ // This is a hack to detect VZEROUPPER but in between popq rbp and ret
+ // It's not pretty but it works
+ if (b == 0xC5) {
+ if ((b = addressSpace.get8(registers.getIP() + 1)) == 0xF8 &&
+ (b = addressSpace.get8(registers.getIP() + 2)) == 0x77)
+ b = addressSpace.get8(registers.getIP() + 3);
+ else
+ goto skip_ret;
+ }
+
+ if (b == 0xC3 || b == 0xCB || b == 0xC2 || b == 0xCA) {
+ uint64_t rbp = registers.getSP();
+ // old esp is ebp less return address
+ registers.setSP(rbp + 16);
+ // pop return address into eip
+ registers.setIP(addressSpace.get64(rbp + 8));
+
+ return UNW_STEP_SUCCESS;
+ }
+
+ skip_ret:
+
uint64_t savedRegisters = registers.getRBP() - 8 * savedRegistersOffset;
for (int i = 0; i < 5; ++i) {
switch (savedRegistersLocations & 0x7) {
@@ -430,6 +474,118 @@ int CompactUnwinder_x86_64<A>::stepWithCompactEncodingFrameless(
}
}
}
+
+ // Note that the order of these registers is so that
+ // registersSaved[0] is the one that will be pushed onto the stack last.
+ // Thus, if we want to walk this from the top, we need to go in reverse.
+ assert(regCount <= 6);
+
+ // check whether we are still in the prologue
+ uint64_t curAddr = functionStart;
+ if (regCount > 0) {
+ for (int8_t i = (int8_t)(regCount) - 1; i >= 0; --i) {
+ if (registers.getIP() == curAddr) {
+ // None of the registers have been modified yet, so we don't need to reload them
+ framelessUnwind(addressSpace, registers.getSP() + 8 * (regCount - (uint64_t)(i + 1)), registers);
+ return UNW_STEP_SUCCESS;
+ } else {
+ assert(curAddr < registers.getIP());
+ }
+
+
+ // pushq %rbp and pushq %rbx is 1 byte. Everything else 2
+ if ((UNWIND_X86_64_REG_RBP == registersSaved[i]) ||
+ (UNWIND_X86_64_REG_RBX == registersSaved[i]))
+ curAddr += 1;
+ else
+ curAddr += 2;
+ }
+ }
+ if (registers.getIP() == curAddr) {
+ // None of the registers have been modified yet, so we don't need to reload them
+ framelessUnwind(addressSpace, registers.getSP() + 8*regCount, registers);
+ return UNW_STEP_SUCCESS;
+ } else {
+ assert(curAddr < registers.getIP());
+ }
+
+
+ // And now for the epilogue
+ {
+ uint8_t i = 0;
+ uint64_t p = registers.getIP();
+ uint8_t b = 0;
+
+ while (true) {
+ b = addressSpace.get8(p++);
+ // This is a hack to detect VZEROUPPER but in between the popq's and ret
+ // It's not pretty but it works
+ if (b == 0xC5) {
+ if ((b = addressSpace.get8(p++)) == 0xF8 && (b = addressSpace.get8(p++)) == 0x77)
+ b = addressSpace.get8(p++);
+ else
+ break;
+ }
+ // popq %rbx popq %rbp
+ if (b == 0x5B || b == 0x5D) {
+ i++;
+ } else if (b == 0x41) {
+ b = addressSpace.get8(p++);
+ if (b == 0x5C || b == 0x5D || b == 0x5E || b == 0x5F)
+ i++;
+ else
+ break;
+ } else if (b == 0xC3 || b == 0xCB || b == 0xC2 || b == 0xCA) {
+ // i pop's haven't happened yet
+ uint64_t savedRegisters = registers.getSP() + 8 * i;
+ if (regCount > 0) {
+ for (int8_t j = (int8_t)(regCount) - 1; j >= (int8_t)(regCount) - i; --j) {
+ uint64_t addr = savedRegisters - 8 * (regCount - (uint64_t)(j));
+ switch (registersSaved[j]) {
+ case UNWIND_X86_64_REG_RBX:
+ registers.setRBX(addressSpace.get64(addr));
+ break;
+ case UNWIND_X86_64_REG_R12:
+ registers.setR12(addressSpace.get64(addr));
+ break;
+ case UNWIND_X86_64_REG_R13:
+ registers.setR13(addressSpace.get64(addr));
+ break;
+ case UNWIND_X86_64_REG_R14:
+ registers.setR14(addressSpace.get64(addr));
+ break;
+ case UNWIND_X86_64_REG_R15:
+ registers.setR15(addressSpace.get64(addr));
+ break;
+ case UNWIND_X86_64_REG_RBP:
+ registers.setRBP(addressSpace.get64(addr));
+ break;
+ default:
+ _LIBUNWIND_DEBUG_LOG("bad register for frameless, encoding=%08X for "
+ "function starting at 0x%llX",
+ encoding, functionStart);
+ _LIBUNWIND_ABORT("invalid compact unwind encoding");
+ }
+ }
+ }
+ framelessUnwind(addressSpace, savedRegisters, registers);
+ return UNW_STEP_SUCCESS;
+ } else {
+ break;
+ }
+ }
+ }
+
+ /*
+ 0x10fe2733a: 5b popq %rbx
+ 0x10fe2733b: 41 5c popq %r12
+ 0x10fe2733d: 41 5d popq %r13
+ 0x10fe2733f: 41 5e popq %r14
+ 0x10fe27341: 41 5f popq %r15
+ 0x10fe27343: 5d popq %rbp
+ */
+
+
uint64_t savedRegisters = registers.getSP() + stackSize - 8 - 8 * regCount;
for (uint32_t i = 0; i < regCount; ++i) {
switch (registersSaved[i]) {