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LLDB20 + stm32mp15x
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From: Stanislav S. <sta...@gm...> - 2025-07-03 00:44:25
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Hello,
I'm debugging stm32mp157c MPU, the board named after QSMP comes from Ka-Ro
Electronics GmbH.
I'm running a debug session from lldb20 and there are a couple issues to
report.
1. When I try to check the sp_hyp register, lldb crashes. It seemed to me
that the problem is lldb itself until I tried to grab registers' descriptor
from openocd. It appears that something is wrong with numbering (see xlm in
the log below). I'm not 100% sure, that sequence must be continuous, I hope
someone can clarify it. If it must, the patch is one string to change
src/target/arm.h:ARM_VFP_V3_D0 value from 51 to 53. It works well, I also
checked that renumbering of d0-d31 registers does not affect values
displayed during the debug session.
2. The second issue is bound to lldp-dap (+ emacs + dap-mode in my setup),
which tries to dereference any 32 bit register which somehow reminds a
pointer... I have not investigated its heuristics but, for example, CPSR
register with its NZC flags in upper bits excites lldb-dap a lot. This
results in attempts to download a memory chunk from inaccessible memory
(given I have not initialized MMU), such as 0x60000000 or 0x80000000 - stm
does not map these regions. So it leads to stalling the session.
Nevertheless, if CPSR's upper flags bits show up as 0x400...., nothing bad
happens, as soon as 0x40000000 is a valid address for stm's periphery. I
have fixed it with a weird approach, given an alternative of pushing
patches into llvm seems undoable for me. CPSR's register could be marked 64
bit. This immediately cools down lldb's interest to dereference its value
at 32 bit armv7 arch and no attempts to access MPU memory are being
conducted.
Kind regards,
Stan
ws@ws:~ % lldb20 --version
lldb version 20.1.2
ws@ws:~ % lldb20
(lldb) file --arch armv7-none-none qsmp-fsbl
Current executable set to 'qsmp-fsbl' (armv7).
(lldb) gdb-remote 3333
(lldb) target modules load --load --set-pc-to-entry --slide 0
Process 1 stopped
* thread #1, stop reason = signal SIGINT
frame #0: 0x2ffc2500 qsmp-fsbl`fsbl._start [inlined] arch.goto at
arch.zig:329:5
326 }
327
328 pub inline fn goto(comptime func: anytype) void {
-> 329 asm volatile ("b %[addr]"
330 :
331 : [addr] "i" (func),
332 );
(lldb) process plugin packet send "qXfer:features:read:target.xml:0,10000"
packet: qXfer:features:read:target.xml:0,10000
response: l<?xml version="1.0"?>
<!DOCTYPE target SYSTEM "gdb-target.dtd">
<target version="1.0">
<architecture>arm</architecture>
<feature name="org.gnu.gdb.arm.core">
<reg name="r0" bitsize="32" regnum="0" save-restore="no" type="uint32"
group="general"/>
<reg name="r1" bitsize="32" regnum="1" save-restore="no" type="uint32"
group="general"/>
<reg name="r2" bitsize="32" regnum="2" save-restore="no" type="uint32"
group="general"/>
<reg name="r3" bitsize="32" regnum="3" save-restore="no" type="uint32"
group="general"/>
<reg name="r4" bitsize="32" regnum="4" save-restore="no" type="uint32"
group="general"/>
<reg name="r5" bitsize="32" regnum="5" save-restore="no" type="uint32"
group="general"/>
<reg name="r6" bitsize="32" regnum="6" save-restore="no" type="uint32"
group="general"/>
<reg name="r7" bitsize="32" regnum="7" save-restore="no" type="uint32"
group="general"/>
<reg name="r8" bitsize="32" regnum="8" save-restore="no" type="uint32"
group="general"/>
<reg name="r9" bitsize="32" regnum="9" save-restore="no" type="uint32"
group="general"/>
<reg name="r10" bitsize="32" regnum="10" save-restore="no" type="uint32"
group="general"/>
<reg name="r11" bitsize="32" regnum="11" save-restore="no" type="uint32"
group="general"/>
<reg name="r12" bitsize="32" regnum="12" save-restore="no" type="uint32"
group="general"/>
<reg name="sp" bitsize="32" regnum="13" save-restore="no" type="data_ptr"
group="general"/>
<reg name="lr" bitsize="32" regnum="14" save-restore="no" type="code_ptr"
group="general"/>
<reg name="pc" bitsize="32" regnum="15" save-restore="no" type="code_ptr"
group="general"/>
<reg name="cpsr" bitsize="32" regnum="25" save-restore="no" type="uint32"
group="general"/>
</feature>
<feature name="net.sourceforge.openocd.banked">
<reg name="sp_usr" bitsize="32" regnum="26" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_usr" bitsize="32" regnum="27" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="r8_fiq" bitsize="32" regnum="28" save-restore="no" type="uint32"
group="banked"/>
<reg name="r9_fiq" bitsize="32" regnum="29" save-restore="no" type="uint32"
group="banked"/>
<reg name="r10_fiq" bitsize="32" regnum="30" save-restore="no"
type="uint32" group="banked"/>
<reg name="r11_fiq" bitsize="32" regnum="31" save-restore="no"
type="uint32" group="banked"/>
<reg name="r12_fiq" bitsize="32" regnum="32" save-restore="no"
type="uint32" group="banked"/>
<reg name="sp_fiq" bitsize="32" regnum="33" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_fiq" bitsize="32" regnum="34" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="sp_irq" bitsize="32" regnum="35" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_irq" bitsize="32" regnum="36" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="sp_svc" bitsize="32" regnum="37" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_svc" bitsize="32" regnum="38" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="sp_abt" bitsize="32" regnum="39" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_abt" bitsize="32" regnum="40" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="sp_und" bitsize="32" regnum="41" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_und" bitsize="32" regnum="42" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="spsr_fiq" bitsize="32" regnum="43" save-restore="no"
type="uint32" group="banked"/>
<reg name="spsr_irq" bitsize="32" regnum="44" save-restore="no"
type="uint32" group="banked"/>
<reg name="spsr_svc" bitsize="32" regnum="45" save-restore="no"
type="uint32" group="banked"/>
<reg name="spsr_abt" bitsize="32" regnum="46" save-restore="no"
type="uint32" group="banked"/>
<reg name="spsr_und" bitsize="32" regnum="47" save-restore="no"
type="uint32" group="banked"/>
<reg name="sp_mon" bitsize="32" regnum="48" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="lr_mon" bitsize="32" regnum="49" save-restore="no"
type="code_ptr" group="banked"/>
<reg name="spsr_mon" bitsize="32" regnum="50" save-restore="no"
type="uint32" group="banked"/>
<reg name="sp_hyp" bitsize="32" regnum="51" save-restore="no"
type="data_ptr" group="banked"/>
<reg name="spsr_hyp" bitsize="32" regnum="52" save-restore="no"
type="uint32" group="banked"/>
</feature>
<feature name="org.gnu.gdb.arm.vfp">
<reg name="d0" bitsize="64" regnum="51" save-restore="no"
type="ieee_double"/>
<reg name="d1" bitsize="64" regnum="52" save-restore="no"
type="ieee_double"/>
<reg name="d2" bitsize="64" regnum="53" save-restore="no"
type="ieee_double"/>
<reg name="d3" bitsize="64" regnum="54" save-restore="no"
type="ieee_double"/>
<reg name="d4" bitsize="64" regnum="55" save-restore="no"
type="ieee_double"/>
<reg name="d5" bitsize="64" regnum="56" save-restore="no"
type="ieee_double"/>
<reg name="d6" bitsize="64" regnum="57" save-restore="no"
type="ieee_double"/>
<reg name="d7" bitsize="64" regnum="58" save-restore="no"
type="ieee_double"/>
<reg name="d8" bitsize="64" regnum="59" save-restore="no"
type="ieee_double"/>
<reg name="d9" bitsize="64" regnum="60" save-restore="no"
type="ieee_double"/>
<reg name="d10" bitsize="64" regnum="61" save-restore="no"
type="ieee_double"/>
<reg name="d11" bitsize="64" regnum="62" save-restore="no"
type="ieee_double"/>
<reg name="d12" bitsize="64" regnum="63" save-restore="no"
type="ieee_double"/>
<reg name="d13" bitsize="64" regnum="64" save-restore="no"
type="ieee_double"/>
<reg name="d14" bitsize="64" regnum="65" save-restore="no"
type="ieee_double"/>
<reg name="d15" bitsize="64" regnum="66" save-restore="no"
type="ieee_double"/>
<reg name="d16" bitsize="64" regnum="67" save-restore="no"
type="ieee_double"/>
<reg name="d17" bitsize="64" regnum="68" save-restore="no"
type="ieee_double"/>
<reg name="d18" bitsize="64" regnum="69" save-restore="no"
type="ieee_double"/>
<reg name="d19" bitsize="64" regnum="70" save-restore="no"
type="ieee_double"/>
<reg name="d20" bitsize="64" regnum="71" save-restore="no"
type="ieee_double"/>
<reg name="d21" bitsize="64" regnum="72" save-restore="no"
type="ieee_double"/>
<reg name="d22" bitsize="64" regnum="73" save-restore="no"
type="ieee_double"/>
<reg name="d23" bitsize="64" regnum="74" save-restore="no"
type="ieee_double"/>
<reg name="d24" bitsize="64" regnum="75" save-restore="no"
type="ieee_double"/>
<reg name="d25" bitsize="64" regnum="76" save-restore="no"
type="ieee_double"/>
<reg name="d26" bitsize="64" regnum="77" save-restore="no"
type="ieee_double"/>
<reg name="d27" bitsize="64" regnum="78" save-restore="no"
type="ieee_double"/>
<reg name="d28" bitsize="64" regnum="79" save-restore="no"
type="ieee_double"/>
<reg name="d29" bitsize="64" regnum="80" save-restore="no"
type="ieee_double"/>
<reg name="d30" bitsize="64" regnum="81" save-restore="no"
type="ieee_double"/>
<reg name="d31" bitsize="64" regnum="82" save-restore="no"
type="ieee_double"/>
<reg name="fpscr" bitsize="32" regnum="83" save-restore="no" type="int"
group="float"/>
</feature>
</target>
(lldb) register read sp_hyp
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/
and include the crash backtrace.
Stack dump:
0. Program arguments: /usr/local/llvm20/bin/lldb
1. HandleCommand(command = "register read sp_hyp")
#0 0x00000008304040a9 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int)
(/usr/local/llvm20/lib/libLLVM.so.20.1+0x44040a9)
#1 0x0000000830401f55 llvm::sys::RunSignalHandlers()
(/usr/local/llvm20/lib/libLLVM.so.20.1+0x4401f55)
#2 0x00000008304047b7 (/usr/local/llvm20/lib/libLLVM.so.20.1+0x44047b7)
#3 0x00000008218064a0 (/lib/libthr.so.3+0x1a4a0)
#4 0x0000000821805a6b (/lib/libthr.so.3+0x19a6b)
#5 0x00000008214702d3 ([vdso]+0x2d3)
#6 0x00000008256c12dc memcpy (/lib/libc.so.7+0x15a2dc)
#7 0x0000000824625991 (/usr/local/llvm20/lib/liblldb.so.20.1+0xe25991)
#8 0x000000082462553c (/usr/local/llvm20/lib/liblldb.so.20.1+0xe2553c)
#9 0x0000000824624f8d (/usr/local/llvm20/lib/liblldb.so.20.1+0xe24f8d)
#10 0x00000008247dac30 (/usr/local/llvm20/lib/liblldb.so.20.1+0xfdac30)
#11 0x00000008247da4ee (/usr/local/llvm20/lib/liblldb.so.20.1+0xfda4ee)
#12 0x0000000824234b31 (/usr/local/llvm20/lib/liblldb.so.20.1+0xa34b31)
#13 0x000000082422524b (/usr/local/llvm20/lib/liblldb.so.20.1+0xa2524b)
#14 0x000000082422993e (/usr/local/llvm20/lib/liblldb.so.20.1+0xa2993e)
#15 0x000000082418c5f0 (/usr/local/llvm20/lib/liblldb.so.20.1+0x98c5f0)
#16 0x000000082416b9e2 (/usr/local/llvm20/lib/liblldb.so.20.1+0x96b9e2)
#17 0x000000082422b8ad (/usr/local/llvm20/lib/liblldb.so.20.1+0xa2b8ad)
#18 0x0000000823e1e0eb lldb::SBDebugger::RunCommandInterpreter(bool, bool)
(/usr/local/llvm20/lib/liblldb.so.20.1+0x61e0eb)
#19 0x000000000020a873 (/usr/local/llvm20/bin/lldb+0x20a873)
#20 0x000000000020b3b9 (/usr/local/llvm20/bin/lldb+0x20b3b9)
#21 0x00000008255ece34 __libc_start1 (/lib/libc.so.7+0x85e34)
LLDB diagnostics will be written to /tmp/diagnostics-19f8fe
Please include the directory content when filing a bug report
Segmentation fault (core dumped)
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