Re: x32 ABI Support (was Re: Three weeks to branching (gdb 7.5 release))

Mark Kettenis
2012-06-10T21:52:21Z

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> Date: Thu, 31 May 2012 11:18:02 -0700
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> > I think this is the wrong approach for x32 support. We should
> > break amd64_x32_init_abi into 2 parts:
> >
> > 1. OS specific part.  It should be private to amd64-tdep.c.

There is no OS specific code in amd64-tdep.c. Only code that
implements the generic OS-agnistic low-level ABI.

> > 2. Generic part.  It should be exported from amd64-tdep.c and can
> > be used by all x32 OSes.

Yes, and that entry point should be amd64_x32_init_abi(). That is the
pattern that has been established, and I see no reason to deviate from
it. So here is the diff I suggested before again with one change: it
moves most of the amd64 Linux support bits into its own function and
calls that from both amd64_linux_init_abi() and
amd64_x32_linux_init_abi(). I'm sure some of those bits are wrong for
x32, but if you want to fix things up from that end, it is fine with
me. The important bit that I care about is getting the inheritance
structure right.

Index: amd64-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-linux-tdep.c,v
retrieving revision 1.50
diff -u -p -r1.50 amd64-linux-tdep.c
--- amd64-linux-tdep.c 12 May 2012 08:54:03 -0000 1.50
+++ amd64-linux-tdep.c 10 Jun 2012 21:39:08 -0000
@@ -1288,41 +1288,12 @@ amd64_linux_core_read_description (struc
}

static void
-amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- const struct target_desc *tdesc = info.target_desc;
- struct tdesc_arch_data *tdesc_data = (void *) info.tdep_info;
- const struct tdesc_feature *feature;
- int valid_p;
-
- gdb_assert (tdesc_data);

linux_init_abi (info, gdbarch);

- tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
- tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
- tdep->sizeof_gregset = 27 * 8;
-
- amd64_init_abi (info, gdbarch);
-
- /* Reserve a number for orig_rax. */
- set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);
-
- if (! tdesc_has_registers (tdesc))
- tdesc = tdesc_amd64_linux;
- tdep->tdesc = tdesc;
-
- feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux");
- if (feature == NULL)
- return;
-
- valid_p = tdesc_numbered_register (feature, tdesc_data,
- AMD64_LINUX_ORIG_RAX_REGNUM,
- "orig_rax");
- if (!valid_p)
- return;
-
tdep->sigtramp_p = amd64_linux_sigtramp_p;
tdep->sigcontext_addr = amd64_linux_sigcontext_addr;
tdep->sc_reg_offset = amd64_linux_sc_reg_offset;
@@ -1330,10 +1301,6 @@ amd64_linux_init_abi (struct gdbarch_inf

tdep->xsave_xcr0_offset = I386_LINUX_XSAVE_XCR0_OFFSET;

- /* GNU/Linux uses SVR4-style shared libraries. */
- set_solib_svr4_fetch_link_map_offsets
- (gdbarch, svr4_lp64_fetch_link_map_offsets);
-
/* Add the %orig_rax register used for syscall restarting. */
set_gdbarch_write_pc (gdbarch, amd64_linux_write_pc);

@@ -1543,6 +1510,88 @@ amd64_linux_init_abi (struct gdbarch_inf

tdep->i386_syscall_record = amd64_linux_syscall_record;
}
+
+static void
+amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+ const struct target_desc *tdesc = info.target_desc;
+ struct tdesc_arch_data *tdesc_data = (void *) info.tdep_info;
+ const struct tdesc_feature *feature;
+ int valid_p;
+
+ gdb_assert (tdesc_data);
+
+ tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
+ tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
+ tdep->sizeof_gregset = 27 * 8;
+
+ amd64_init_abi (info, gdbarch);
+
+ /* Reserve a number for orig_rax. */
+ set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);
+
+ if (! tdesc_has_registers (tdesc))
+ tdesc = tdesc_amd64_linux;
+ tdep->tdesc = tdesc;
+
+ feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux");
+ if (feature == NULL)
+ return;
+
+ valid_p = tdesc_numbered_register (feature, tdesc_data,
+ AMD64_LINUX_ORIG_RAX_REGNUM,
+ "orig_rax");
+ if (!valid_p)
+ return;
+
+ amd64_linux_init_abi_common (info, gdbarch);
+
+ /* GNU/Linux uses SVR4-style shared libraries. */
+ set_solib_svr4_fetch_link_map_offsets
+ (gdbarch, svr4_lp64_fetch_link_map_offsets);
+}
+
+static void
+amd64_x32_linux_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+ const struct target_desc *tdesc = info.target_desc;
+ struct tdesc_arch_data *tdesc_data = (void *) info.tdep_info;
+ const struct tdesc_feature *feature;
+ int valid_p;
+
+ gdb_assert (tdesc_data);
+
+ tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
+ tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
+ tdep->sizeof_gregset = 27 * 8;
+
+ amd64_x32_init_abi (info, gdbarch);
+
+ /* Reserve a number for orig_rax. */
+ set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);
+
+ if (! tdesc_has_registers (tdesc))
+ tdesc = tdesc_x32_linux;
+ tdep->tdesc = tdesc;
+
+ feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux");
+ if (feature == NULL)
+ return;
+
+ valid_p = tdesc_numbered_register (feature, tdesc_data,
+ AMD64_LINUX_ORIG_RAX_REGNUM,
+ "orig_rax");
+ if (!valid_p)
+ return;
+
+ amd64_linux_init_abi_common (info, gdbarch);
+
+ /* GNU/Linux uses SVR4-style shared libraries. */
+ set_solib_svr4_fetch_link_map_offsets
+ (gdbarch, svr4_ilp32_fetch_link_map_offsets);
+}
\f

/* Provide a prototype to silence -Wmissing-prototypes. */
@@ -1553,6 +1602,8 @@ _initialize_amd64_linux_tdep (void)
{
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
GDB_OSABI_LINUX, amd64_linux_init_abi);
+ gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x64_32,
+ GDB_OSABI_LINUX, amd64_x32_linux_init_abi);

/* Initialize the Linux target description. */
initialize_tdesc_amd64_linux ();
Index: amd64-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-tdep.c,v
retrieving revision 1.104
diff -u -p -r1.104 amd64-tdep.c
--- amd64-tdep.c 14 May 2012 18:56:40 -0000 1.104
+++ amd64-tdep.c 10 Jun 2012 21:39:09 -0000
@@ -258,7 +258,8 @@ static const char *amd64_word_names[] =
static const char *amd64_dword_names[] =
{
"eax", "ebx", "ecx", "edx", "esi", "edi", "ebp", "esp",
- "r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d"
+ "r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d",
+ "eip"
};

/* Return the name of register REGNUM. */
@@ -2729,6 +2730,43 @@ amd64_init_abi (struct gdbarch_info info
set_gdbarch_stap_parse_special_token (gdbarch,
i386_stap_parse_special_token);
}
+\f
+
+static struct type *
+amd64_x32_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ switch (regnum - tdep->eax_regnum)
+ {
+ case AMD64_RBP_REGNUM: /* %ebp */
+ case AMD64_RSP_REGNUM: /* %esp */
+ return builtin_type (gdbarch)->builtin_data_ptr;
+ case AMD64_RIP_REGNUM: /* %eip */
+ return builtin_type (gdbarch)->builtin_func_ptr;
+ }
+
+ return i386_pseudo_register_type (gdbarch, regnum);
+}
+
+void
+amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+ const struct target_desc *tdesc = info.target_desc;
+
+ amd64_init_abi (info, gdbarch);
+
+ if (! tdesc_has_registers (tdesc))
+ tdesc = tdesc_x32;
+ tdep->tdesc = tdesc;
+
+ tdep->num_dword_regs = 17;
+ set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type);
+
+ set_gdbarch_long_bit (gdbarch, 32);
+ set_gdbarch_ptr_bit (gdbarch, 32);
+}

/* Provide a prototype to silence -Wmissing-prototypes. */
void _initialize_amd64_tdep (void);
Index: amd64-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/amd64-tdep.h,v
retrieving revision 1.21
diff -u -p -r1.21 amd64-tdep.h
--- amd64-tdep.h 4 Jan 2012 08:16:56 -0000 1.21
+++ amd64-tdep.h 10 Jun 2012 21:39:09 -0000
@@ -80,6 +80,8 @@ extern void amd64_displaced_step_fixup (
struct regcache *regs);

extern void amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch);
+extern void amd64_x32_init_abi (struct gdbarch_info info,
+ struct gdbarch *gdbarch);

/* Fill register REGNUM in REGCACHE with the appropriate
floating-point or SSE register value from *FXSAVE. If REGNUM is