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[binutils-gdb] Support for DTrace USDT probes in x86_64 targets.
- From: Jose E.Marchesi <jemarch at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 17 Feb 2015 15:43:00 -0000
- Subject: [binutils-gdb] Support for DTrace USDT probes in x86_64 targets.
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=c3e3045e5ce820055e2823e8c5b03b0e99a4b514
commit c3e3045e5ce820055e2823e8c5b03b0e99a4b514
Author: Jose E. Marchesi <jose.marchesi@oracle.com>
Date: Tue Feb 17 16:04:01 2015 +0100
Support for DTrace USDT probes in x86_64 targets.
This patch adds the target-specific code in order to support the
calculation of DTrace probes arguments in x86_64 targets, and also the
enabling and disabling of probes. This is done by implementing the
`dtrace_*' gdbarch handlers.
gdb/ChangeLog:
2015-02-17 Jose E. Marchesi <jose.marchesi@oracle.com>
* amd64-linux-tdep.c: Include "parser-defs.h" and "user-regs.h".
(amd64_dtrace_parse_probe_argument): New function.
(amd64_dtrace_probe_is_enabled): Likewise.
(amd64_dtrace_enable_probe): Likewise.
(amd64_dtrace_disable_probe): Likewise.
(amd64_linux_init_abi): Register the
`gdbarch_dtrace_probe_argument', `gdbarch_dtrace_enable_probe',
`gdbarch_dtrace_disable_probe' and
`gdbarch_dtrace_probe_is_enabled' hooks.
(amd64_dtrace_disabled_probe_sequence_1): New constant.
(amd64_dtrace_disabled_probe_sequence_2): Likewise.
(amd64_dtrace_enable_probe_sequence): Likewise.
(amd64_dtrace_disable_probe_sequence): Likewise.
Diff:
---
gdb/ChangeLog | 16 ++++++
gdb/amd64-linux-tdep.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 164 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4cc7b77..fc39c68 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+2015-02-17 Jose E. Marchesi <jose.marchesi@oracle.com>
+
+ * amd64-linux-tdep.c: Include "parser-defs.h" and "user-regs.h".
+ (amd64_dtrace_parse_probe_argument): New function.
+ (amd64_dtrace_probe_is_enabled): Likewise.
+ (amd64_dtrace_enable_probe): Likewise.
+ (amd64_dtrace_disable_probe): Likewise.
+ (amd64_linux_init_abi): Register the
+ `gdbarch_dtrace_probe_argument', `gdbarch_dtrace_enable_probe',
+ `gdbarch_dtrace_disable_probe' and
+ `gdbarch_dtrace_probe_is_enabled' hooks.
+ (amd64_dtrace_disabled_probe_sequence_1): New constant.
+ (amd64_dtrace_disabled_probe_sequence_2): Likewise.
+ (amd64_dtrace_enable_probe_sequence): Likewise.
+ (amd64_dtrace_disable_probe_sequence): Likewise.
+
2015-01-17 Jose E. Marchesi <jose.marchesi@oracle.com>
* breakpoint.c (BREAK_ARGS_HELP): Help string updated to mention
diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index 5db04c0..b126366 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -28,6 +28,8 @@
#include "gdbtypes.h"
#include "reggroups.h"
#include "regset.h"
+#include "parser-defs.h"
+#include "user-regs.h"
#include "amd64-linux-tdep.h"
#include "i386-linux-tdep.h"
#include "linux-tdep.h"
@@ -1643,6 +1645,146 @@ amd64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
&amd64_linux_xstateregset, "XSAVE extended state", cb_data);
}
+/* The instruction sequences used in x86_64 machines for a
+ disabled is-enabled probe. */
+
+const gdb_byte amd64_dtrace_disabled_probe_sequence_1[] = {
+ /* xor %rax, %rax */ 0x48, 0x33, 0xc0,
+ /* nop */ 0x90,
+ /* nop */ 0x90
+};
+
+const gdb_byte amd64_dtrace_disabled_probe_sequence_2[] = {
+ /* xor %rax, %rax */ 0x48, 0x33, 0xc0,
+ /* ret */ 0xc3,
+ /* nop */ 0x90
+};
+
+/* The instruction sequence used in x86_64 machines for enabling a
+ DTrace is-enabled probe. */
+
+const gdb_byte amd64_dtrace_enable_probe_sequence[] = {
+ /* mov $0x1, %eax */ 0xb8, 0x01, 0x00, 0x00, 0x00
+};
+
+/* The instruction sequence used in x86_64 machines for disabling a
+ DTrace is-enabled probe. */
+
+const gdb_byte amd64_dtrace_disable_probe_sequence[] = {
+ /* xor %rax, %rax; nop; nop */ 0x48, 0x33, 0xC0, 0x90, 0x90
+};
+
+/* Implementation of `gdbarch_dtrace_probe_is_enabled', as defined in
+ gdbarch.h. */
+
+static int
+amd64_dtrace_probe_is_enabled (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+ gdb_byte buf[5];
+
+ /* This function returns 1 if the instructions at ADDR do _not_
+ follow any of the amd64_dtrace_disabled_probe_sequence_*
+ patterns.
+
+ Note that ADDR is offset 3 bytes from the beginning of these
+ sequences. */
+
+ read_code (addr - 3, buf, 5);
+ return (memcmp (buf, amd64_dtrace_disabled_probe_sequence_1, 5) != 0
+ && memcmp (buf, amd64_dtrace_disabled_probe_sequence_2, 5) != 0);
+}
+
+/* Implementation of `gdbarch_dtrace_enable_probe', as defined in
+ gdbarch.h. */
+
+static void
+amd64_dtrace_enable_probe (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+ /* Note also that ADDR is offset 3 bytes from the beginning of
+ amd64_dtrace_enable_probe_sequence. */
+
+ write_memory (addr - 3, amd64_dtrace_enable_probe_sequence, 5);
+}
+
+/* Implementation of `gdbarch_dtrace_disable_probe', as defined in
+ gdbarch.h. */
+
+static void
+amd64_dtrace_disable_probe (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+ /* Note also that ADDR is offset 3 bytes from the beginning of
+ amd64_dtrace_disable_probe_sequence. */
+
+ write_memory (addr - 3, amd64_dtrace_disable_probe_sequence, 5);
+}
+
+/* Implementation of `gdbarch_dtrace_parse_probe_argument', as defined
+ in gdbarch.h. */
+
+static void
+amd64_dtrace_parse_probe_argument (struct gdbarch *gdbarch,
+ struct parser_state *pstate,
+ int narg)
+{
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ struct frame_info *this_frame = get_selected_frame (NULL);
+ struct stoken str;
+
+ /* DTrace probe arguments can be found on the ABI-defined places for
+ regular arguments at the current PC. The probe abstraction
+ currently supports up to 12 arguments for probes. */
+
+ if (narg < 6)
+ {
+ static const int arg_reg_map[6] =
+ {
+ AMD64_RDI_REGNUM, /* Arg 1. */
+ AMD64_RSI_REGNUM, /* Arg 2. */
+ AMD64_RDX_REGNUM, /* Arg 3. */
+ AMD64_RCX_REGNUM, /* Arg 4. */
+ AMD64_R8_REGNUM, /* Arg 5. */
+ AMD64_R9_REGNUM /* Arg 6. */
+ };
+ int regno = arg_reg_map[narg];
+ const char *regname = user_reg_map_regnum_to_name (gdbarch, regno);
+
+ write_exp_elt_opcode (pstate, OP_REGISTER);
+ str.ptr = regname;
+ str.length = strlen (regname);
+ write_exp_string (pstate, str);
+ write_exp_elt_opcode (pstate, OP_REGISTER);
+ }
+ else
+ {
+ /* Additional arguments are passed on the stack. */
+ CORE_ADDR sp;
+ const char *regname = user_reg_map_regnum_to_name (gdbarch, AMD64_RSP_REGNUM);
+
+ /* Displacement. */
+ write_exp_elt_opcode (pstate, OP_LONG);
+ write_exp_elt_type (pstate, builtin_type (gdbarch)->builtin_long);
+ write_exp_elt_longcst (pstate, narg - 6);
+ write_exp_elt_opcode (pstate, OP_LONG);
+
+ /* Register: SP. */
+ write_exp_elt_opcode (pstate, OP_REGISTER);
+ str.ptr = regname;
+ str.length = strlen (regname);
+ write_exp_string (pstate, str);
+ write_exp_elt_opcode (pstate, OP_REGISTER);
+
+ write_exp_elt_opcode (pstate, BINOP_ADD);
+
+ /* Cast to long. */
+ write_exp_elt_opcode (pstate, UNOP_CAST);
+ write_exp_elt_type (pstate,
+ lookup_pointer_type (builtin_type (gdbarch)->builtin_long));
+ write_exp_elt_opcode (pstate, UNOP_CAST);
+
+ write_exp_elt_opcode (pstate, UNOP_IND);
+ }
+}
+
static void
amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -1907,6 +2049,12 @@ amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
/* GNU/Linux uses SVR4-style shared libraries. */
set_solib_svr4_fetch_link_map_offsets
(gdbarch, svr4_lp64_fetch_link_map_offsets);
+
+ /* Register DTrace handlers. */
+ set_gdbarch_dtrace_parse_probe_argument (gdbarch, amd64_dtrace_parse_probe_argument);
+ set_gdbarch_dtrace_probe_is_enabled (gdbarch, amd64_dtrace_probe_is_enabled);
+ set_gdbarch_dtrace_enable_probe (gdbarch, amd64_dtrace_enable_probe);
+ set_gdbarch_dtrace_disable_probe (gdbarch, amd64_dtrace_disable_probe);
}
static void