#0x10 — Public Fediverse posts

OK so ELR_EL3 is 0xe005a98 which is inside __dl___memmove_aarch64 "ldp x10, x11, [x4, #0x20].

I think this is the address the exception would resume at, which means the *previous* instruction generated the fault. That's ldp x8, x9, [x1, #0x10].

Seems like ldp is the aarch64 equivalent of ldrd, so we're loading two 64-bit values from (x1+0x10) and writing to x8 and x9.

Which means x1 must be a bad pointer.

Been stuck for a while on this assembly code on iOS (AArch64):

stp x29, x30, [sp, #0x10]!

This raises a SIGBUS error

sp is 16-byte aligned, and x29 and x30 (fp and lr) are valid as well.
Any advice?

@helge For reference, in case it can help anyone else, putting a breakpoint in `init(0` and looking at the closest couple of stack frames, you'll see an entry like this:

#2 0x000000010063df94 in implicit closure #2 in implicit closure #1 in variable initialization expression of ReKeyApp._store ()

or

#2 0x0000000100631cdc in implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store ()

It very helpfully tells you the class (or struct) causing the instantiation.

Would be nice if #Xcode actually selected the line in the source instead of a line in a block of assembly, but the comments in that are helpful too:

ReKey`implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store:
0x100631cc0 <+0>: stp x20, x19, [sp, #-0x20]!
0x100631cc4 <+4>: stp x29, x30, [sp, #0x10]
0x100631cc8 <+8>: add x29, sp, #0x10
0x100631ccc <+12>: mov x0, #0x0
0x100631cd0 <+16>: bl 0x10062d700 ; type metadata accessor for ReKey.Store at <compiler-generated>
0x100631cd4 <+20>: mov x20, x0
0x100631cd8 <+24>: bl 0x100623770 ; ReKey.Store.__allocating_init() -> ReKey.Store at Store.swift:43
-> 0x100631cdc <+28>: ldp x29, x30, [sp, #0x10]
0x100631ce0 <+32>: ldp x20, x19, [sp], #0x20
0x100631ce4 <+36>: ret

@helge For reference, in case it can help anyone else, putting a breakpoint in `init(0` and looking at the closest couple of stack frames, you'll see an entry like this:

#2 0x000000010063df94 in implicit closure #2 in implicit closure #1 in variable initialization expression of ReKeyApp._store ()

or

#2 0x0000000100631cdc in implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store ()

It very helpfully tells you the class (or struct) causing the instantiation.

Would be nice if #Xcode actually selected the line in the source instead of a line in a block of assembly, but the comments in that are helpful too:

ReKey`implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store:
0x100631cc0 <+0>: stp x20, x19, [sp, #-0x20]!
0x100631cc4 <+4>: stp x29, x30, [sp, #0x10]
0x100631cc8 <+8>: add x29, sp, #0x10
0x100631ccc <+12>: mov x0, #0x0
0x100631cd0 <+16>: bl 0x10062d700 ; type metadata accessor for ReKey.Store at <compiler-generated>
0x100631cd4 <+20>: mov x20, x0
0x100631cd8 <+24>: bl 0x100623770 ; ReKey.Store.__allocating_init() -> ReKey.Store at Store.swift:43
-> 0x100631cdc <+28>: ldp x29, x30, [sp, #0x10]
0x100631ce0 <+32>: ldp x20, x19, [sp], #0x20
0x100631ce4 <+36>: ret

@helge For reference, in case it can help anyone else, putting a breakpoint in `init(0` and looking at the closest couple of stack frames, you'll see an entry like this:

#2 0x000000010063df94 in implicit closure #2 in implicit closure #1 in variable initialization expression of ReKeyApp._store ()

or

#2 0x0000000100631cdc in implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store ()

It very helpfully tells you the class (or struct) causing the instantiation.

Would be nice if #Xcode actually selected the line in the source instead of a line in a block of assembly, but the comments in that are helpful too:

ReKey`implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store:
0x100631cc0 <+0>: stp x20, x19, [sp, #-0x20]!
0x100631cc4 <+4>: stp x29, x30, [sp, #0x10]
0x100631cc8 <+8>: add x29, sp, #0x10
0x100631ccc <+12>: mov x0, #0x0
0x100631cd0 <+16>: bl 0x10062d700 ; type metadata accessor for ReKey.Store at <compiler-generated>
0x100631cd4 <+20>: mov x20, x0
0x100631cd8 <+24>: bl 0x100623770 ; ReKey.Store.__allocating_init() -> ReKey.Store at Store.swift:43
-> 0x100631cdc <+28>: ldp x29, x30, [sp, #0x10]
0x100631ce0 <+32>: ldp x20, x19, [sp], #0x20
0x100631ce4 <+36>: ret

@helge For reference, in case it can help anyone else, putting a breakpoint in `init(0` and looking at the closest couple of stack frames, you'll see an entry like this:

#2 0x000000010063df94 in implicit closure #2 in implicit closure #1 in variable initialization expression of ReKeyApp._store ()

or

#2 0x0000000100631cdc in implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store ()

It very helpfully tells you the class (or struct) causing the instantiation.

Would be nice if #Xcode actually selected the line in the source instead of a line in a block of assembly, but the comments in that are helpful too:

ReKey`implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store:
0x100631cc0 <+0>: stp x20, x19, [sp, #-0x20]!
0x100631cc4 <+4>: stp x29, x30, [sp, #0x10]
0x100631cc8 <+8>: add x29, sp, #0x10
0x100631ccc <+12>: mov x0, #0x0
0x100631cd0 <+16>: bl 0x10062d700 ; type metadata accessor for ReKey.Store at <compiler-generated>
0x100631cd4 <+20>: mov x20, x0
0x100631cd8 <+24>: bl 0x100623770 ; ReKey.Store.__allocating_init() -> ReKey.Store at Store.swift:43
-> 0x100631cdc <+28>: ldp x29, x30, [sp, #0x10]
0x100631ce0 <+32>: ldp x20, x19, [sp], #0x20
0x100631ce4 <+36>: ret

@helge For reference, in case it can help anyone else, putting a breakpoint in `init(0` and looking at the closest couple of stack frames, you'll see an entry like this:

#2 0x000000010063df94 in implicit closure #2 in implicit closure #1 in variable initialization expression of ReKeyApp._store ()

or

#2 0x0000000100631cdc in implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store ()

It very helpfully tells you the class (or struct) causing the instantiation.

Would be nice if #Xcode actually selected the line in the source instead of a line in a block of assembly, but the comments in that are helpful too:

ReKey`implicit closure #2 in implicit closure #1 in variable initialization expression of ContentView._store:
0x100631cc0 <+0>: stp x20, x19, [sp, #-0x20]!
0x100631cc4 <+4>: stp x29, x30, [sp, #0x10]
0x100631cc8 <+8>: add x29, sp, #0x10
0x100631ccc <+12>: mov x0, #0x0
0x100631cd0 <+16>: bl 0x10062d700 ; type metadata accessor for ReKey.Store at <compiler-generated>
0x100631cd4 <+20>: mov x20, x0
0x100631cd8 <+24>: bl 0x100623770 ; ReKey.Store.__allocating_init() -> ReKey.Store at Store.swift:43
-> 0x100631cdc <+28>: ldp x29, x30, [sp, #0x10]
0x100631ce0 <+32>: ldp x20, x19, [sp], #0x20
0x100631ce4 <+36>: ret