On 25/09/2020 20:45, Kinsey Moore wrote:
-----Original Message-----
From: Sebastian Huber <sebastian.hu...@embedded-brains.de>
Sent: Friday, September 25, 2020 11:20
To: Kinsey Moore <kinsey.mo...@oarcorp.com>; devel@rtems.org
Subject: Re: [PATCH v1 6/8] score: Add AArch64 port
On 25/09/2020 17:27, Kinsey Moore wrote:
diff --git a/cpukit/include/rtems/score/tls.h
b/cpukit/include/rtems/score/tls.h
index 65a49d87be..8c15eee569 100644
--- a/cpukit/include/rtems/score/tls.h
+++ b/cpukit/include/rtems/score/tls.h
@@ -85,7 +85,7 @@ typedef struct TLS_Thread_control_block {
struct TLS_Thread_control_block *tcb;
#else /* !__i386__ */
TLS_Dynamic_thread_vector *dtv;
-#if CPU_SIZEOF_POINTER == 4
+#if CPU_SIZEOF_POINTER == 4 || CPU_SIZEOF_POINTER == 8
uintptr_t reserved;
#endif
#endif /* __i386__ */
Are you sure this is correct? TLS_Dynamic_thread_vector *dtv; is 8 bytes in
this case.
[]
Dropping this change causes sptls01 to fail. This was added pretty early in the
implementation, so I've just had to go back and refresh my memories of the
reasoning behind it which still may not be entirely accurate. Sptls01 fails
without this patch because under AArch64/LP64, gcc and gdb expect a 16 byte
offset to the TLS data segment. If this patch is not present, the TCB is half
the size it needs to be and so getting a TLS variable address ends up indexing
into the TCB+TLS data segment at a compiler-expected offset that does not
correspond to the actual data layout. I adjusted this to match the compiler's
offset expectations. There may be a better way to fix this issue, but this is
the most appropriate location I could find that made the most sense. The
biggest worry I have here is that this may break other architectures that also
have 8 byte pointers. When I fix the file headers, I'll see if I can make this
more specific to AArch64.
Yes, the AArch64 seems to use a TCB size of 16 bytes. It would be good
to reference all ABI related documents in the CPU supplement.
For PowerPC 64-Bit ELF V2 ABI, the TCB is 8 bytes
(implementation-dependent extra fields may be added before the DTV pointer):
http://openpowerfoundation.org/wp-content/uploads/resources/leabi-prd/content/dbdoclet.50655241_50444.html
I guess we have to make this definition a bit more architecture-dependent.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
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