[PATCH 1/9] Support the fs_base and gs_base registers on i386.

John Baldwin
2019-01-22T18:43:47Z

As on amd64, these registers hold the base address of the fs and gs
segments, respectively. For i386 these two registers are 32 bits.

gdb/ChangeLog:

* amd64-fbsd-nat.c (amd64_fbsd_nat_target::read_description):
Update calls to i386_target_description to add 'segments'
parameter.
* amd64-tdep.c (amd64_init_abi): Set tdep->fsbase_regnum. Don't
add segment base registers.
* arch/i386.c (i386_create_target_description): Add 'segments'
parameter to enable segment base registers.
* arch/i386.h (i386_create_target_description): Likewise.
* features/i386/32bit-segments.xml: New file.
* features/i386/32bit-segments.c: Generate.
* i386-fbsd-nat.c (i386_fbsd_nat_target::read_description): Update
call to i386_target_description to add 'segments' parameter.
* i386-fbsd-tdep.c (i386fbsd_core_read_description): Likewise.
* i386-go32-tdep.c (i386_go32_init_abi): Likewise.
* i386-linux-tdep.c (i386_linux_read_description): Likewise.
* i386-tdep.c (i386_validate_tdesc_p): Add segment base registers
if feature is present.
(i386_gdbarch_init): Pass I386_NUM_REGS to set_gdbarch_num_regs.
Add 'segments' parameter to call to i386_target_description.
(i386_target_description): Add 'segments' parameter to enable
segment base registers.
(_initialize_i386_tdep) [GDB_SELF_TEST]: Add 'segments' parameter
to call to i386_target_description.
* i386-tdep.h (struct gdbarch_tdep): Add 'fsbase_regnum'.
(enum i386_regnum): Add I386_FSBASE_REGNUM and I386_GSBASE_REGNUM.
Define I386_NUM_REGS.
(i386_target_description): Add 'segments' parameter to enable
segment base registers.

gdb/gdbserver/ChangeLog:

* linux-x86-tdesc.c (i386_linux_read_description): Update call to
i386_create_target_description for 'segments' parameter.
* lynx-i386-low.c (lynx_i386_arch_setup): Likewise.
* nto-x86-low.c (nto_x86_arch_setup): Likewise.
* win32-i386-low.c (i386_arch_setup): Likewise.
---
gdb/ChangeLog | 31 ++++++++++++++++++++++++++
gdb/amd64-fbsd-nat.c | 4 ++--
gdb/amd64-tdep.c | 10 +--------
gdb/arch/i386.c | 6 ++++-
gdb/arch/i386.h | 3 ++-
gdb/features/i386/32bit-segments.c | 15 +++++++++++++
gdb/features/i386/32bit-segments.xml | 12 ++++++++++
gdb/gdbserver/ChangeLog | 8 +++++++
gdb/gdbserver/linux-x86-tdesc.c | 2 +-
gdb/gdbserver/lynx-i386-low.c | 2 +-
gdb/gdbserver/nto-x86-low.c | 2 +-
gdb/gdbserver/win32-i386-low.c | 2 +-
gdb/i386-fbsd-nat.c | 2 +-
gdb/i386-fbsd-tdep.c | 2 +-
gdb/i386-go32-tdep.c | 2 +-
gdb/i386-linux-tdep.c | 2 +-
gdb/i386-tdep.c | 33 +++++++++++++++++++++-------
gdb/i386-tdep.h | 12 ++++++++--
18 files changed, 119 insertions(+), 31 deletions(-)
create mode 100644 gdb/features/i386/32bit-segments.c
create mode 100644 gdb/features/i386/32bit-segments.xml

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8e03dbf883..4afd5b664e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,34 @@
+2019-01-22 John Baldwin <jhb@FreeBSD.org>
+
+ * amd64-fbsd-nat.c (amd64_fbsd_nat_target::read_description):
+ Update calls to i386_target_description to add 'segments'
+ parameter.
+ * amd64-tdep.c (amd64_init_abi): Set tdep->fsbase_regnum. Don't
+ add segment base registers.
+ * arch/i386.c (i386_create_target_description): Add 'segments'
+ parameter to enable segment base registers.
+ * arch/i386.h (i386_create_target_description): Likewise.
+ * features/i386/32bit-segments.xml: New file.
+ * features/i386/32bit-segments.c: Generate.
+ * i386-fbsd-nat.c (i386_fbsd_nat_target::read_description): Update
+ call to i386_target_description to add 'segments' parameter.
+ * i386-fbsd-tdep.c (i386fbsd_core_read_description): Likewise.
+ * i386-go32-tdep.c (i386_go32_init_abi): Likewise.
+ * i386-linux-tdep.c (i386_linux_read_description): Likewise.
+ * i386-tdep.c (i386_validate_tdesc_p): Add segment base registers
+ if feature is present.
+ (i386_gdbarch_init): Pass I386_NUM_REGS to set_gdbarch_num_regs.
+ Add 'segments' parameter to call to i386_target_description.
+ (i386_target_description): Add 'segments' parameter to enable
+ segment base registers.
+ (_initialize_i386_tdep) [GDB_SELF_TEST]: Add 'segments' parameter
+ to call to i386_target_description.
+ * i386-tdep.h (struct gdbarch_tdep): Add 'fsbase_regnum'.
+ (enum i386_regnum): Add I386_FSBASE_REGNUM and I386_GSBASE_REGNUM.
+ Define I386_NUM_REGS.
+ (i386_target_description): Add 'segments' parameter to enable
+ segment base registers.
+
2019-01-22 Philippe Waroquiers <philippe.waroquiers@skynet.be>

* event-top.c (handle_line_of_input): use unique_xmalloc_ptr for
diff --git a/gdb/amd64-fbsd-nat.c b/gdb/amd64-fbsd-nat.c
index 6d8e12b033..39ba69d9bf 100644
--- a/gdb/amd64-fbsd-nat.c
+++ b/gdb/amd64-fbsd-nat.c
@@ -190,13 +190,13 @@ amd64_fbsd_nat_target::read_description ()
if (is64)
return amd64_target_description (xcr0, true);
else
- return i386_target_description (xcr0);
+ return i386_target_description (xcr0, false);
}
#endif
if (is64)
return amd64_target_description (X86_XSTATE_SSE_MASK, true);
else
- return i386_target_description (X86_XSTATE_SSE_MASK);
+ return i386_target_description (X86_XSTATE_SSE_MASK, false);
}

#if defined(HAVE_PT_GETDBREGS) && defined(USE_SIGTRAP_SIGINFO)
diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index d4143ae155..1eb0bcdf17 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -3107,15 +3107,7 @@ amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch,

if (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.segments") != NULL)
{
- const struct tdesc_feature *feature =
- tdesc_find_feature (tdesc, "org.gnu.gdb.i386.segments");
- struct tdesc_arch_data *tdesc_data_segments =
- (struct tdesc_arch_data *) info.tdep_info;
-
- tdesc_numbered_register (feature, tdesc_data_segments,
- AMD64_FSBASE_REGNUM, "fs_base");
- tdesc_numbered_register (feature, tdesc_data_segments,
- AMD64_GSBASE_REGNUM, "gs_base");
+ tdep->fsbase_regnum = AMD64_FSBASE_REGNUM;
}

if (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.pkeys") != NULL)
diff --git a/gdb/arch/i386.c b/gdb/arch/i386.c
index 73987da97b..311b5fd8c8 100644
--- a/gdb/arch/i386.c
+++ b/gdb/arch/i386.c
@@ -28,11 +28,12 @@
#include "../features/i386/32bit-avx512.c"
#include "../features/i386/32bit-mpx.c"
#include "../features/i386/32bit-pkeys.c"
+#include "../features/i386/32bit-segments.c"

/* Create i386 target descriptions according to XCR0. */

target_desc *
-i386_create_target_description (uint64_t xcr0, bool is_linux)
+i386_create_target_description (uint64_t xcr0, bool is_linux, bool segments)
{
target_desc *tdesc = allocate_target_description ();

@@ -53,6 +54,9 @@ i386_create_target_description (uint64_t xcr0, bool is_linux)
if (is_linux)
regnum = create_feature_i386_32bit_linux (tdesc, regnum);

+ if (segments)
+ regnum = create_feature_i386_32bit_segments (tdesc, regnum);
+
if (xcr0 & X86_XSTATE_AVX)
regnum = create_feature_i386_32bit_avx (tdesc, regnum);

diff --git a/gdb/arch/i386.h b/gdb/arch/i386.h
index a6a801b818..af8c6bd73f 100644
--- a/gdb/arch/i386.h
+++ b/gdb/arch/i386.h
@@ -18,4 +18,5 @@
#include "common/tdesc.h"
#include <stdint.h>

-target_desc *i386_create_target_description (uint64_t xcr0, bool is_linux);
+target_desc *i386_create_target_description (uint64_t xcr0, bool is_linux,
+ bool segments);
diff --git a/gdb/features/i386/32bit-segments.c b/gdb/features/i386/32bit-segments.c
new file mode 100644
index 0000000000..c22c3dfbc3
--- /dev/null
+++ b/gdb/features/i386/32bit-segments.c
@@ -0,0 +1,15 @@
+/* THIS FILE IS GENERATED. -*- buffer-read-only: t -*- vi:set ro:
+ Original: 32bit-segments.xml */
+
+#include "common/tdesc.h"
+
+static int
+create_feature_i386_32bit_segments (struct target_desc *result, long regnum)
+{
+ struct tdesc_feature *feature;
+
+ feature = tdesc_create_feature (result, "org.gnu.gdb.i386.segments");
+ tdesc_create_reg (feature, "fs_base", regnum++, 1, NULL, 32, "int");
+ tdesc_create_reg (feature, "gs_base", regnum++, 1, NULL, 32, "int");
+ return regnum;
+}
diff --git a/gdb/features/i386/32bit-segments.xml b/gdb/features/i386/32bit-segments.xml
new file mode 100644
index 0000000000..098948e5ec
--- /dev/null
+++ b/gdb/features/i386/32bit-segments.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2016-2018 Free Software Foundation, Inc.
+
+ Copying and distribution of this file, with or without modification,
+ are permitted in any medium without royalty provided the copyright
+ notice and this notice are preserved. -->
+
+
+<feature name="org.gnu.gdb.i386.segments">
+ <reg name="fs_base" bitsize="32" type="int"/>
+ <reg name="gs_base" bitsize="32" type="int"/>
+</feature>
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 5312ca9919..fc8b37976a 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,11 @@
+2019-01-22 John Baldwin <jhb@FreeBSD.org>
+
+ * linux-x86-tdesc.c (i386_linux_read_description): Update call to
+ i386_create_target_description for 'segments' parameter.
+ * lynx-i386-low.c (lynx_i386_arch_setup): Likewise.
+ * nto-x86-low.c (nto_x86_arch_setup): Likewise.
+ * win32-i386-low.c (i386_arch_setup): Likewise.
+
2019-01-21 Tom Tromey <tom@tromey.com>

* tracepoint.c: Fix includes.
diff --git a/gdb/gdbserver/linux-x86-tdesc.c b/gdb/gdbserver/linux-x86-tdesc.c
index 04bccc84ed..8f24a3d72d 100644
--- a/gdb/gdbserver/linux-x86-tdesc.c
+++ b/gdb/gdbserver/linux-x86-tdesc.c
@@ -87,7 +87,7 @@ i386_linux_read_description (uint64_t xcr0)

if (*tdesc == NULL)
{
- *tdesc = i386_create_target_description (xcr0, true);
+ *tdesc = i386_create_target_description (xcr0, true, false);

init_target_desc (*tdesc, i386_expedite_regs);
}
diff --git a/gdb/gdbserver/lynx-i386-low.c b/gdb/gdbserver/lynx-i386-low.c
index 0731d2a73d..77ec8235e0 100644
--- a/gdb/gdbserver/lynx-i386-low.c
+++ b/gdb/gdbserver/lynx-i386-low.c
@@ -331,7 +331,7 @@ static void
lynx_i386_arch_setup (void)
{
struct target_desc *tdesc
- = i386_create_target_description (X86_XSTATE_SSE_MASK, false);
+ = i386_create_target_description (X86_XSTATE_SSE_MASK, false, false);

init_target_desc (tdesc, i386_expedite_regs);

diff --git a/gdb/gdbserver/nto-x86-low.c b/gdb/gdbserver/nto-x86-low.c
index 19c9acf42b..6930664e00 100644
--- a/gdb/gdbserver/nto-x86-low.c
+++ b/gdb/gdbserver/nto-x86-low.c
@@ -89,7 +89,7 @@ nto_x86_arch_setup (void)
{
the_low_target.num_regs = 16;
struct target_desc *tdesc
- = i386_create_target_description (X86_XSTATE_SSE_MASK, false);
+ = i386_create_target_description (X86_XSTATE_SSE_MASK, false, false);

init_target_desc (tdesc, i386_expedite_regs);

diff --git a/gdb/gdbserver/win32-i386-low.c b/gdb/gdbserver/win32-i386-low.c
index 30f7af7553..9b7bc40225 100644
--- a/gdb/gdbserver/win32-i386-low.c
+++ b/gdb/gdbserver/win32-i386-low.c
@@ -439,7 +439,7 @@ i386_arch_setup (void)
false, false);
const char **expedite_regs = amd64_expedite_regs;
#else
- tdesc = i386_create_target_description (X86_XSTATE_SSE_MASK, false);
+ tdesc = i386_create_target_description (X86_XSTATE_SSE_MASK, false, false);
const char **expedite_regs = i386_expedite_regs;
#endif

diff --git a/gdb/i386-fbsd-nat.c b/gdb/i386-fbsd-nat.c
index 855572143b..8ff104cf72 100644
--- a/gdb/i386-fbsd-nat.c
+++ b/gdb/i386-fbsd-nat.c
@@ -160,7 +160,7 @@ i386_fbsd_nat_target::read_description ()
if (x86bsd_xsave_len == 0)
xcr0 = X86_XSTATE_SSE_MASK;

- return i386_target_description (xcr0);
+ return i386_target_description (xcr0, false);
}
#endif

diff --git a/gdb/i386-fbsd-tdep.c b/gdb/i386-fbsd-tdep.c
index 82dfbd5c35..43b15167ae 100644
--- a/gdb/i386-fbsd-tdep.c
+++ b/gdb/i386-fbsd-tdep.c
@@ -267,7 +267,7 @@ i386fbsd_core_read_description (struct gdbarch *gdbarch,
struct target_ops *target,
bfd *abfd)
{
- return i386_target_description (i386fbsd_core_read_xcr0 (abfd));
+ return i386_target_description (i386fbsd_core_read_xcr0 (abfd), false);
}

/* Similar to i386_supply_fpregset, but use XSAVE extended state. */
diff --git a/gdb/i386-go32-tdep.c b/gdb/i386-go32-tdep.c
index 5a18f35f99..200de53cd8 100644
--- a/gdb/i386-go32-tdep.c
+++ b/gdb/i386-go32-tdep.c
@@ -35,7 +35,7 @@ i386_go32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

/* DJGPP does not support the SSE registers. */
if (!tdesc_has_registers (info.target_desc))
- tdep->tdesc = i386_target_description (X86_XSTATE_X87_MASK);
+ tdep->tdesc = i386_target_description (X86_XSTATE_X87_MASK, false);

/* Native compiler is GCC, which uses the SVR4 register numbering
even in COFF and STABS. See the comment in i386_gdbarch_init,
diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c
index 0f344b0710..b2461836ad 100644
--- a/gdb/i386-linux-tdep.c
+++ b/gdb/i386-linux-tdep.c
@@ -694,7 +694,7 @@ i386_linux_read_description (uint64_t xcr0)
[(xcr0 & X86_XSTATE_PKRU) ? 1 : 0];

if (*tdesc == NULL)
- *tdesc = i386_create_target_description (xcr0, true);
+ *tdesc = i386_create_target_description (xcr0, true, false);

return *tdesc;
}
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 8b2c72ac7b..65a5d6ab95 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8175,7 +8175,7 @@ i386_validate_tdesc_p (struct gdbarch_tdep *tdep,
const struct tdesc_feature *feature_core;

const struct tdesc_feature *feature_sse, *feature_avx, *feature_mpx,
- *feature_avx512, *feature_pkeys;
+ *feature_avx512, *feature_pkeys, *feature_segments;
int i, num_regs, valid_p;

if (! tdesc_has_registers (tdesc))
@@ -8198,6 +8198,9 @@ i386_validate_tdesc_p (struct gdbarch_tdep *tdep,
/* Try AVX512 registers. */
feature_avx512 = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.avx512");

+ /* Try segment base registers. */
+ feature_segments = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.segments");
+
/* Try PKEYS */
feature_pkeys = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.pkeys");

@@ -8307,6 +8310,16 @@ i386_validate_tdesc_p (struct gdbarch_tdep *tdep,
tdep->mpx_register_names[i]);
}

+ if (feature_segments)
+ {
+ if (tdep->fsbase_regnum < 0)
+ tdep->fsbase_regnum = I386_FSBASE_REGNUM;
+ valid_p &= tdesc_numbered_register (feature_segments, tdesc_data,
+ tdep->fsbase_regnum, "fs_base");
+ valid_p &= tdesc_numbered_register (feature_segments, tdesc_data,
+ tdep->fsbase_regnum + 1, "gs_base");
+ }
+
if (feature_pkeys)
{
tdep->xcr0 |= X86_XSTATE_PKRU;
@@ -8543,14 +8556,14 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Even though the default ABI only includes general-purpose registers,
floating-point registers and the SSE registers, we have to leave a
gap for the upper AVX, MPX and AVX512 registers. */
- set_gdbarch_num_regs (gdbarch, I386_PKEYS_NUM_REGS);
+ set_gdbarch_num_regs (gdbarch, I386_NUM_REGS);

set_gdbarch_gnu_triplet_regexp (gdbarch, i386_gnu_triplet_regexp);

/* Get the x86 target description from INFO. */
tdesc = info.target_desc;
if (! tdesc_has_registers (tdesc))
- tdesc = i386_target_description (X86_XSTATE_SSE_MASK);
+ tdesc = i386_target_description (X86_XSTATE_SSE_MASK, false);
tdep->tdesc = tdesc;

tdep->num_core_regs = I386_NUM_GREGS + I387_NUM_REGS;
@@ -8592,6 +8605,9 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
tdep->pkru_regnum = -1;
tdep->num_pkeys_regs = 0;

+ /* No segment base registers. */
+ tdep->fsbase_regnum = -1;
+
tdesc_data = tdesc_data_alloc ();

set_gdbarch_relocate_instruction (gdbarch, i386_relocate_instruction);
@@ -8717,20 +8733,21 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Return the target description for a specified XSAVE feature mask. */

const struct target_desc *
-i386_target_description (uint64_t xcr0)
+i386_target_description (uint64_t xcr0, bool segments)
{
static target_desc *i386_tdescs \
- [2/*SSE*/][2/*AVX*/][2/*MPX*/][2/*AVX512*/][2/*PKRU*/] = {};
+ [2/*SSE*/][2/*AVX*/][2/*MPX*/][2/*AVX512*/][2/*PKRU*/][2/*segments*/] = {};
target_desc **tdesc;

tdesc = &i386_tdescs[(xcr0 & X86_XSTATE_SSE) ? 1 : 0]
[(xcr0 & X86_XSTATE_AVX) ? 1 : 0]
[(xcr0 & X86_XSTATE_MPX) ? 1 : 0]
[(xcr0 & X86_XSTATE_AVX512) ? 1 : 0]
- [(xcr0 & X86_XSTATE_PKRU) ? 1 : 0];
+ [(xcr0 & X86_XSTATE_PKRU) ? 1 : 0]
+ [segments ? 1 : 0];

if (*tdesc == NULL)
- *tdesc = i386_create_target_description (xcr0, false);
+ *tdesc = i386_create_target_description (xcr0, false, segments);

return *tdesc;
}
@@ -9072,7 +9089,7 @@ Show Intel Memory Protection Extensions specific variables."),

for (auto &a : xml_masks)
{
- auto tdesc = i386_target_description (a.mask);
+ auto tdesc = i386_target_description (a.mask, false);

selftests::record_xml_tdesc (a.xml, tdesc);
}
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 2532306e5c..c0d494824c 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -200,6 +200,10 @@ struct gdbarch_tdep
/* PKEYS register names. */
const char **pkeys_register_names;

+ /* Register number for %fsbase. Set this to -1 to indicate the
+ absence of segment base registers. */
+ int fsbase_regnum;
+
/* Target description. */
const struct target_desc *tdesc;

@@ -296,7 +300,9 @@ enum i386_regnum
I386_K7_REGNUM = I386_K0_REGNUM + 7,
I386_ZMM0H_REGNUM, /* %zmm0h */
I386_ZMM7H_REGNUM = I386_ZMM0H_REGNUM + 7,
- I386_PKRU_REGNUM
+ I386_PKRU_REGNUM,
+ I386_FSBASE_REGNUM,
+ I386_GSBASE_REGNUM
};

/* Register numbers of RECORD_REGMAP. */
@@ -337,6 +343,7 @@ enum record_i386_regnum
#define I386_MPX_NUM_REGS (I386_BNDSTATUS_REGNUM + 1)
#define I386_AVX512_NUM_REGS (I386_ZMM7H_REGNUM + 1)
#define I386_PKEYS_NUM_REGS (I386_PKRU_REGNUM + 1)
+#define I386_NUM_REGS (I386_GSBASE_REGNUM + 1)

/* Size of the largest register. */
#define I386_MAX_REGISTER_SIZE 64
@@ -440,7 +447,8 @@ extern int i386_svr4_reg_to_regnum (struct gdbarch *gdbarch, int reg);

extern int i386_process_record (struct gdbarch *gdbarch,
struct regcache *regcache, CORE_ADDR addr);
-extern const struct target_desc *i386_target_description (uint64_t xcr0);
+extern const struct target_desc *i386_target_description (uint64_t xcr0,
+ bool segments);

/* Return true iff the current target is MPX enabled. */
extern int i386_mpx_enabled (void);
--
2.19.2