Re: [RFC] Add support for PPC Altivec registers in gcore

Carlos Eduardo Seo
2007-10-30T21:12:12Z

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Ulrich Weigand wrote:
>
> Completely removing all the fallbacks seems quite a bit of work;
> if you want to work on it that would certainly be welcome.
>
> However, I think it would be OK to start with having the gdbarch
> variable only contain the *extra* register sets, beyond the core
> and floating-point sets.
>
Ok. So, this would require removing the FILL_FPXREGSET ifdefs and all
the fill_fpxregset fallbacks. I think this is OK, but won't it break
anything in x86?
>
> If we do not have a collect_regset, we certainly do not want to
> write an note section containing uninitialized data. The
> elfcore_write_ppc_vmx call needs to be inside the "if" block ...
Corrected.

Thanks,

- --
Carlos Eduardo Seo
Software Engineer
IBM Linux Technology Center
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2007-10-30 Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>

* linux-nat.c (linux_nat_do_thread_registers): Added
support for PPC Altivec registers.
* ppc-linux-nat.c: Removed definitions of SIZEOF_VRREGS
and gdb_vrregset_t.
* gregset.h: Added definitions of SIZEOF_VRREGS and
gdb_vrregset_t.

Index: src/gdb/linux-nat.c
===================================================================
--- src.orig/gdb/linux-nat.c
+++ src/gdb/linux-nat.c
@@ -2616,6 +2616,7 @@ linux_nat_do_thread_registers (bfd *obfd
{
gdb_gregset_t gregs;
gdb_fpregset_t fpregs;
+ gdb_vrregset_t vrregs;
#ifdef FILL_FPXREGSET
gdb_fpxregset_t fpxregs;
#endif
@@ -2676,6 +2677,19 @@ linux_nat_do_thread_registers (bfd *obfd
note_size,
&fpxregs, sizeof (fpxregs));
#endif
+
+ if (core_regset_p
+ && (regset = gdbarch_regset_from_core_section (gdbarch, ".reg-ppc-vmx",
+ sizeof (vrregs))) != NULL
+ && regset->collect_regset != NULL)
+ {
+ regset->collect_regset (regset, regcache, -1,
+ &vrregs, sizeof (vrregs));
+ note_data = (char *) elfcore_write_ppc_vmx (obfd,
+ note_data,
+ note_size,
+ &vrregs, sizeof (vrregs));
+ }
return note_data;
}

Index: src/gdb/ppc-linux-nat.c
===================================================================
--- src.orig/gdb/ppc-linux-nat.c
+++ src/gdb/ppc-linux-nat.c
@@ -79,38 +79,6 @@
#define PTRACE_GETSIGINFO 0x4202
#endif

-/* This oddity is because the Linux kernel defines elf_vrregset_t as
- an array of 33 16 bytes long elements. I.e. it leaves out vrsave.
- However the PTRACE_GETVRREGS and PTRACE_SETVRREGS requests return
- the vrsave as an extra 4 bytes at the end. I opted for creating a
- flat array of chars, so that it is easier to manipulate for gdb.
-
- There are 32 vector registers 16 bytes longs, plus a VSCR register
- which is only 4 bytes long, but is fetched as a 16 bytes
- quantity. Up to here we have the elf_vrregset_t structure.
- Appended to this there is space for the VRSAVE register: 4 bytes.
- Even though this vrsave register is not included in the regset
- typedef, it is handled by the ptrace requests.
-
- Note that GNU/Linux doesn't support little endian PPC hardware,
- therefore the offset at which the real value of the VSCR register
- is located will be always 12 bytes.
-
- The layout is like this (where x is the actual value of the vscr reg): */
-
-/* *INDENT-OFF* */
-/*
- |.|.|.|.|.....|.|.|.|.||.|.|.|x||.|
- <-------> <-------><-------><->
- VR0 VR31 VSCR VRSAVE
-*/
-/* *INDENT-ON* */
-
-#define SIZEOF_VRREGS 33*16+4
-
-typedef char gdb_vrregset_t[SIZEOF_VRREGS];
-
-
/* On PPC processors that support the the Signal Processing Extension
(SPE) APU, the general-purpose registers are 64 bits long.
However, the ordinary Linux kernel PTRACE_PEEKUSER / PTRACE_POKEUSER
Index: src/gdb/gregset.h
===================================================================
--- src.orig/gdb/gregset.h
+++ src/gdb/gregset.h
@@ -72,4 +72,37 @@ extern void fill_fpxregset (const struct
gdb_fpxregset_t *fpxregs, int regno);
#endif

+/* For PPC Altivec support */
+
+/* This oddity is because the Linux kernel defines elf_vrregset_t as
+ an array of 33 16 bytes long elements. I.e. it leaves out vrsave.
+ However the PTRACE_GETVRREGS and PTRACE_SETVRREGS requests return
+ the vrsave as an extra 4 bytes at the end. I opted for creating a
+ flat array of chars, so that it is easier to manipulate for gdb.
+
+ There are 32 vector registers 16 bytes longs, plus a VSCR register
+ which is only 4 bytes long, but is fetched as a 16 bytes
+ quantity. Up to here we have the elf_vrregset_t structure.
+ Appended to this there is space for the VRSAVE register: 4 bytes.
+ Even though this vrsave register is not included in the regset
+ typedef, it is handled by the ptrace requests.
+
+ Note that GNU/Linux doesn't support little endian PPC hardware,
+ therefore the offset at which the real value of the VSCR register
+ is located will be always 12 bytes.
+
+ The layout is like this (where x is the actual value of the vscr reg): */
+
+/* *INDENT-OFF* */
+/*
+ |.|.|.|.|.....|.|.|.|.||.|.|.|x||.|
+ <-------> <-------><-------><->
+ VR0 VR31 VSCR VRSAVE
+*/
+/* *INDENT-ON* */
+
+#define SIZEOF_VRREGS 33*16+4
+
+typedef char gdb_vrregset_t[SIZEOF_VRREGS];
+
#endif

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