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Re: [RFA/gdbserver] x86 LynxOS-178: Adjust floating-point context structure
> > gdb/gdbserver/ChangeLog:
> >
> > * lynx-i386-low.c (LYNXOS_178): New macro.
> > (usr_fcontext_t) <LYNXOS_178>: Provide a definition that matches
> > the layout on LynxOS-178.
>
> This syntax (with < >) is usually meant to denote fields (as if you were
> referring to field LYNXOS_178 in structure usr_fcontext_t). To denote an
> #ifdef context (which is what I understand you want to do), I usually see
> this syntax:
>
> [LYNXOS_178] (usr_fcontext_t): ...
>
> For example:
>
> https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/ChangeLog-2017;h=aaadf142a4641ecd3feb26bc1dfa83dcc19e713c;hb=HEAD#l13806
Grumpf. I keep getting confused over this. Of course, you are right,
and this is explained in the GCS.
>
> > (lynx_i386_fill_fpregset, lynx_i386_store_fpregset): Do not
> > handle floating point registers that are not supported by
> > LynxOS-178.
> >
> > OK to push to master?
>
> Otherwise, it looks good to me.
Thanks. Attached is the patch I ended up pushing to master.
gdb/gdbserver/ChangeLog:
* lynx-i386-low.c (LYNXOS_178): New macro.
[LYNXOS_178] (usr_fcontext_t): Provide a definition that matches
the layout on LynxOS-178.
(lynx_i386_fill_fpregset, lynx_i386_store_fpregset): Do not
handle floating point registers that are not supported by
LynxOS-178.
--
Joel
>From 55271bf969c2c09b98aecd97b36170fbf76c3fc4 Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Thu, 10 May 2018 12:01:39 -0500
Subject: [PATCH] x86 LynxOS-178: Adjust floating-point context structure
The floating point context structure on x86 LynxOS-178 is not
the same as on LynxOS 5.x. As a consequence, trying to print
the return value of a function returning a float, for instance,
yields incorrect results.
This patch fixes the issue by providing an updated definition
for LynxOS-178 (the reason why we cannot access the actual definition
provided by the system still remains true).
gdb/gdbserver/ChangeLog:
* lynx-i386-low.c (LYNXOS_178): New macro.
[LYNXOS_178] (usr_fcontext_t): Provide a definition that matches
the layout on LynxOS-178.
(lynx_i386_fill_fpregset, lynx_i386_store_fpregset): Do not
handle floating point registers that are not supported by
LynxOS-178.
---
gdb/gdbserver/ChangeLog | 9 +++++++++
gdb/gdbserver/lynx-i386-low.c | 38 +++++++++++++++++++++++++++++++++++++-
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 36915cf..5e7ea10 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,12 @@
+2018-05-10 Joel Brobecker <brobecker@adacore.com>
+
+ * lynx-i386-low.c (LYNXOS_178): New macro.
+ [LYNXOS_178] (usr_fcontext_t): Provide a definition that matches
+ the layout on LynxOS-178.
+ (lynx_i386_fill_fpregset, lynx_i386_store_fpregset): Do not
+ handle floating point registers that are not supported by
+ LynxOS-178.
+
2018-05-10 Tom Tromey <tom@tromey.com>
* configure: Rebuild.
diff --git a/gdb/gdbserver/lynx-i386-low.c b/gdb/gdbserver/lynx-i386-low.c
index 37c0dc9..a8817b4 100644
--- a/gdb/gdbserver/lynx-i386-low.c
+++ b/gdb/gdbserver/lynx-i386-low.c
@@ -25,7 +25,15 @@
/* The following two typedefs are defined in a .h file which is not
in the standard include path (/sys/include/family/x86/ucontext.h),
- so we just duplicate them here. */
+ so we just duplicate them here.
+
+ Unfortunately for us, the definition of this structure differs between
+ LynxOS 5.x and LynxOS 178. Rather than duplicate the code, we use
+ different definitions depending on the target. */
+
+#ifdef VMOS_DEV
+#define LYNXOS_178
+#endif
/* General register context */
typedef struct usr_econtext {
@@ -52,6 +60,28 @@ typedef struct usr_econtext {
uint32_t uec_gs;
} usr_econtext_t;
+#if defined(LYNXOS_178)
+
+/* Floating point register context */
+typedef struct usr_fcontext {
+ uint32_t ufc_control;
+ uint32_t ufc_status;
+ uint32_t ufc_tag;
+ uint8_t *ufc_inst_off;
+ uint32_t ufc_inst_sel;
+ uint8_t *ufc_data_off;
+ uint32_t ufc_data_sel;
+ struct ufp387_real {
+ uint16_t umant4;
+ uint16_t umant3;
+ uint16_t umant2;
+ uint16_t umant1;
+ uint16_t us_and_e;
+ } ufc_reg[8];
+} usr_fcontext_t;
+
+#else /* This is LynxOS 5.x. */
+
/* Floating point and SIMD register context */
typedef struct usr_fcontext {
uint16_t ufc_control;
@@ -87,6 +117,8 @@ typedef struct usr_fcontext {
char ureserved[16][14];
} usr_fcontext_t;
+#endif
+
/* The index of various registers inside the regcache. */
enum lynx_i386_gdb_regnum
@@ -219,6 +251,7 @@ lynx_i386_fill_fpregset (struct regcache *regcache, char *buf)
buf + offsetof (usr_fcontext_t, ufc_data_sel));
collect_register (regcache, I386_FOOFF_REGNUM,
buf + offsetof (usr_fcontext_t, ufc_data_off));
+#if !defined(LYNXOS_178)
collect_16bit_register (regcache, I386_FOP_REGNUM,
buf + offsetof (usr_fcontext_t, ufc_opcode));
@@ -229,6 +262,7 @@ lynx_i386_fill_fpregset (struct regcache *regcache, char *buf)
+ i * sizeof (struct uxmm_register));
collect_register (regcache, I386_MXCSR_REGNUM,
buf + offsetof (usr_fcontext_t, usse_mxcsr));
+#endif
}
/* This is the supply counterpart for collect_16bit_register:
@@ -277,6 +311,7 @@ lynx_i386_store_fpregset (struct regcache *regcache, const char *buf)
buf + offsetof (usr_fcontext_t, ufc_data_sel));
supply_register (regcache, I386_FOOFF_REGNUM,
buf + offsetof (usr_fcontext_t, ufc_data_off));
+#if !defined(LYNXOS_178)
supply_16bit_register (regcache, I386_FOP_REGNUM,
buf + offsetof (usr_fcontext_t, ufc_opcode));
@@ -287,6 +322,7 @@ lynx_i386_store_fpregset (struct regcache *regcache, const char *buf)
+ i * sizeof (struct uxmm_register));
supply_register (regcache, I386_MXCSR_REGNUM,
buf + offsetof (usr_fcontext_t, usse_mxcsr));
+#endif
}
/* Implements the lynx_target_ops.arch_setup routine. */
--
2.1.4