> On Jan 8, 2024, at 13:04, Linus Torvalds wrote:
>
> On Mon, 8 Jan 2024 at 12:18, Dirk Hohndel via subsurface
> <subsurface@subsurface-divelog.org> wrote:
>
> "objdump -d" is horrible at disassembly.
no kidding.
> For some unfathomable reason, it doesn't look at relocation
> information, so when it disassembles any instruction with relocations,
> the end result is garbage.
>
> And no, adding "-r" to make it show relocation information isn't much
> better. The disassembly is still garbage, but there will now be an
> extra line that basically says "if I wasn't showing you garbage, I
> would use this line to tell you what the garbage should have been".
>
> So then you can - manually - use that relocation information to show
> what the disassembly should have been.
see below
> is the call chain result from here:
>
> 8 Subsurface-mobile 0x000000010027589c
> QMLManager::~QMLManager() + 68 (qmlmanager.cpp:608)
>
> but that's really just the return point from that
>
>> 5d78: 94000000 bl 0x5d78 <QMLManager::~QMLManager()+0x40>
>
> and that's very much an example of the whole "objdump is showing
> garbage". That function isn't calling itself, but that's what objdump
> -d shows, because it doesn't look at the reloc info.
>
> Anyway, I think this has probably been compiled with some sanitizer.
> With "-r" to objdump, at least we'd see what the call target for that
> "bl" instruction is, which might give some clue.
5d60: 34000068 cbz w8, 0x5d6c <QMLManager::~QMLManager()+0x34>
5d64: 9103e260 add x0, x19, #248
5d68: 94000000 bl 0x5d68 <QMLManager::~QMLManager()+0x30>
0000000000005d68: ARM64_RELOC_BRANCH26
__ZN11QFileDevice5closeEv
5d6c: 90000008 adrp x8, 0x5000 <QMLManager::~QMLManager()+0x34>
0000000000005d6c: ARM64_RELOC_PAGE21
__ZN10QMLManager10m_instanceE
5d70: f900011f str xzr, [x8]
0000000000005d70: ARM64_RELOC_PAGEOFF12
__ZN10QMLManager10m_instanceE
5d74: 91044260 add x0, x19, #272
5d78: 94000000 bl 0x5d78 <QMLManager::~QMLManager()+0x40>
0000000000005d78: ARM64_RELOC_BRANCH26 __ZN8IosShareD1Ev
5d7c: 9103e260 add x0, x19, #248
5d80: 94000000 bl 0x5d80 <QMLManager::~QMLManager()+0x48>
0000000000005d80: ARM64_RELOC_BRANCH26 __ZN5QFileD1Ev
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