JDevlieghere created this revision. JDevlieghere added a reviewer: jasonmolenda. Herald added subscribers: danielkiss, kristof.beyls.
Add support for hardware breakpoints on ARM64 Repository: rLLDB LLDB https://reviews.llvm.org/D76411 Files: lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.h
Index: lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.h =================================================================== --- lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.h +++ lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.h @@ -26,10 +26,12 @@ DNBArchMachARM64(MachThread *thread) : m_thread(thread), m_state(), m_disabled_watchpoints(), - m_watchpoint_hw_index(-1), m_watchpoint_did_occur(false), + m_disabled_breakpoints(), m_watchpoint_hw_index(-1), + m_watchpoint_did_occur(false), m_watchpoint_resume_single_step_enabled(false), m_saved_register_states() { m_disabled_watchpoints.resize(16); + m_disabled_breakpoints.resize(16); memset(&m_dbg_save, 0, sizeof(m_dbg_save)); } @@ -62,7 +64,13 @@ static const uint8_t *SoftwareBreakpointOpcode(nub_size_t byte_size); static uint32_t GetCPUType(); + virtual uint32_t NumSupportedHardwareBreakpoints(); virtual uint32_t NumSupportedHardwareWatchpoints(); + + virtual uint32_t EnableHardwareBreakpoint(nub_addr_t addr, nub_size_t size, + bool also_set_on_task); + virtual bool DisableHardwareBreakpoint(uint32_t hw_break_index, + bool also_set_on_task); virtual uint32_t EnableHardwareWatchpoint(nub_addr_t addr, nub_size_t size, bool read, bool write, bool also_set_on_task); @@ -229,10 +237,11 @@ State m_state; arm_debug_state64_t m_dbg_save; - // arm64 doesn't keep the disabled watchpoint values in the debug register - // context like armv7; + // arm64 doesn't keep the disabled watchpoint and breakpoint values in the + // debug register context like armv7; // we need to save them aside when we disable them temporarily. std::vector<disabled_watchpoint> m_disabled_watchpoints; + std::vector<disabled_watchpoint> m_disabled_breakpoints; // The following member variables should be updated atomically. int32_t m_watchpoint_hw_index; Index: lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp =================================================================== --- lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp +++ lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp @@ -666,6 +666,112 @@ return g_num_supported_hw_watchpoints; } +uint32_t DNBArchMachARM64::NumSupportedHardwareBreakpoints() { + // Set the init value to something that will let us know that we need to + // autodetect how many breakpoints are supported dynamically... + static uint32_t g_num_supported_hw_breakpoints = UINT_MAX; + if (g_num_supported_hw_breakpoints == UINT_MAX) { + // Set this to zero in case we can't tell if there are any HW breakpoints + g_num_supported_hw_breakpoints = 0; + + size_t len; + uint32_t n = 0; + len = sizeof(n); + if (::sysctlbyname("hw.optional.breakpoint", &n, &len, NULL, 0) == 0) { + g_num_supported_hw_breakpoints = n; + DNBLogThreadedIf(LOG_THREAD, "hw.optional.breakpoint=%u", n); + } else { +// For AArch64 we would need to look at ID_AA64DFR0_EL1 but debugserver runs in +// EL0 so it can't access that reg. The kernel should have filled in the +// sysctls based on it though. +#if defined(__arm__) + uint32_t register_DBGDIDR; + + asm("mrc p14, 0, %0, c0, c0, 0" : "=r"(register_DBGDIDR)); + uint32_t numWRPs = bits(register_DBGDIDR, 31, 28); + // Zero is reserved for the WRP count, so don't increment it if it is zero + if (numWRPs > 0) + numWRPs++; + g_num_supported_hw_breakpoints = numWRPs; + DNBLogThreadedIf(LOG_THREAD, + "Number of supported hw breakpoint via asm(): %d", + g_num_supported_hw_breakpoints); +#endif + } + } + return g_num_supported_hw_breakpoints; +} + +uint32_t DNBArchMachARM64::EnableHardwareBreakpoint(nub_addr_t addr, + nub_size_t size, + bool also_set_on_task) { + DNBLogThreadedIf(LOG_WATCHPOINTS, + "DNBArchMachARM64::EnableHardwareBreakpoint(addr = " + "0x%8.8llx, size = %zu)", + (uint64_t)addr, size); + + const uint32_t num_hw_breakpoints = NumSupportedHardwareBreakpoints(); + + nub_addr_t aligned_bp_address = addr; + uint32_t control_value = 0; + + switch (size) { + case 2: + control_value = (0x3 << 5) | 7; + aligned_bp_address &= ~1; + break; + case 4: + control_value = (0xfu << 5) | 7; + aligned_bp_address &= ~3; + break; + }; + + // Read the debug state + kern_return_t kret = GetDBGState(false); + if (kret == KERN_SUCCESS) { + // Check to make sure we have the needed hardware support + uint32_t i = 0; + + for (i = 0; i < num_hw_breakpoints; ++i) { + if ((m_state.dbg.__bcr[i] & BCR_ENABLE) == 0) + break; // We found an available hw breakpoint slot (in i) + } + + // See if we found an available hw breakpoint slot above + if (i < num_hw_breakpoints) { + m_state.dbg.__bvr[i] = aligned_bp_address; + m_state.dbg.__bcr[i] = control_value; + + DNBLogThreadedIf(LOG_WATCHPOINTS, + "DNBArchMachARM64::EnableHardwareBreakpoint() " + "adding breakpoint on address 0x%llx with control " + "register value 0x%x", + (uint64_t)m_state.dbg.__bvr[i], + (uint32_t)m_state.dbg.__bcr[i]); + + // The kernel will set the MDE_ENABLE bit in the MDSCR_EL1 for us + // automatically, don't need to do it here. + kret = SetDBGState(also_set_on_task); + + DNBLogThreadedIf(LOG_WATCHPOINTS, + "DNBArchMachARM64::" + "EnableHardwareBreakpoint() " + "SetDBGState() => 0x%8.8x.", + kret); + + if (kret == KERN_SUCCESS) + return i; + } else { + DNBLogThreadedIf(LOG_WATCHPOINTS, + "DNBArchMachARM64::" + "EnableHardwareBreakpoint(): All " + "hardware resources (%u) are in use.", + num_hw_breakpoints); + } + } + return INVALID_NUB_HW_INDEX; +} + uint32_t DNBArchMachARM64::EnableHardwareWatchpoint(nub_addr_t addr, nub_size_t size, bool read, bool write, @@ -905,6 +1011,32 @@ return (kret == KERN_SUCCESS); } +bool DNBArchMachARM64::DisableHardwareBreakpoint(uint32_t hw_index, + bool also_set_on_task) { + kern_return_t kret = GetDBGState(false); + if (kret != KERN_SUCCESS) + return false; + + const uint32_t num_hw_points = NumSupportedHardwareBreakpoints(); + if (hw_index >= num_hw_points) + return false; + + m_disabled_breakpoints[hw_index].addr = m_state.dbg.__bvr[hw_index]; + m_disabled_breakpoints[hw_index].control = m_state.dbg.__bcr[hw_index]; + + m_state.dbg.__bcr[hw_index] = 0; + DNBLogThreadedIf(LOG_WATCHPOINTS, + "DNBArchMachARM64::" + "DisableHardwareBreakpoint( %u ) - WVR%u = " + "0x%8.8llx BCR%u = 0x%8.8llx", + hw_index, hw_index, (uint64_t)m_state.dbg.__bvr[hw_index], + hw_index, (uint64_t)m_state.dbg.__bcr[hw_index]); + + kret = SetDBGState(also_set_on_task); + + return (kret == KERN_SUCCESS); +} + // This is for checking the Byte Address Select bits in the DBRWCRn_EL1 control // register. // Returns -1 if the trailing bit patterns are not one of:
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