[RFA/gdbserver] x86 LynxOS-178: Adjust floating-point context structure
Commit Message
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.
(usr_fcontext_t) <LYNXOS_178>: 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.
OK to push to master?
Comments
On 2018-05-10 11:05, Joel Brobecker wrote:
> 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.
> (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
> (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.
Simon
@@ -24,7 +24,15 @@
/* 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 {
@@ -51,6 +59,28 @@ 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;
@@ -86,6 +116,8 @@ 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
@@ -218,6 +250,7 @@ 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));
@@ -228,6 +261,7 @@ 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:
@@ -276,6 +310,7 @@ 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));
@@ -286,6 +321,7 @@ 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. */