[Bug 31308] Remote Tools for Visual Studio 2012 RC for Windows on ARM (WoA) crashes due to invalid user TLS register value access

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=31308

--- Comment #4 from Anastasius Focht <focht at gmx.net> 2012-07-25 16:21:56 CDT ---
Hello André,

I think I figured out what TPIDRURW value means.
The routine that accesses it looks like some inlined alloca() implementation
for ARM.

I added some comments what I think it does

--- snip ---
...
.text:00419D3C  SUBS.W          R12, SP, R4,LSL#2  ; get end addr of req.
buffer
.text:00419D40  MRC             p15, 0, R4,c13,c0, 2 ; get TEB
.text:00419D44  LDR             R4, [R4,#8]          ; teb->Tib.StackLimit
.text:00419D48  CMP             R12, R4
.text:00419D4A  BCC             loc_419D58   ; doesn't fit, grow active stack
.text:00419D4C  SUB.W           R4, SP, R12  ; fits, new buffer start
.text:00419D50  BX              LR
.text:00419D52  MOVS.W          R12, #0
.text:00419D56  B               loc_419D48
; grow the stack
.text:00419D58  PUSH            {R5,R6}
.text:00419D5A  MOV             R6, R12
.text:00419D5C  BFC.W           R6, #0, #0xC        ; align
.text:00419D60  SUB.W           R4, R4, #0x1000     ; move down by PAGE_SIZE
.text:00419D64  LDR             R5, [R4]            ; touch the page
; touching page below teb->Tib.StackLimit should update the field to new limit
; until DeallocationStack is reached (exhausted)
.text:00419D66  CMP             R4, R6
.text:00419D68  BNE             loc_419D60
.text:00419D6A  POP             {R5,R6}
.text:00419D6C  SUB.W           R4, SP, R12         ; new buffer start
.text:00419D70  BX              LR
--- snip ---

I patched Wine to set TPIDRURW to the TEB value for each newly created thread
in signal_init_thread().
This should work but unfortunately my kernel doesn't preserve the value of
TPIDRURW (gets overwritten).

The crash you're seeing is because another thread context, where TPIDRURW has
been zeroed out again.

For each newly created thread you have to set TPIDRURW to the appropriate TEB
and the kernel must be modified to save/restore TPIDRURW value for each thread
on context switch (hence this bug is actually upstream).

Regards

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