[V3,6/9] Support for DTrace USDT probes in x86_64 targets.
Commit Message
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:
2014-10-28 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.
---
gdb/ChangeLog | 16 ++++++
gdb/amd64-linux-tdep.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 164 insertions(+)
Comments
On Tuesday, October 28 2014, Jose E. Marchesi wrote:
> 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.
Thanks for the patch, Jose. This is much easier to read after you
reworked based on Pedro's suggestions.
I have no further comments to make.
> gdb/ChangeLog:
>
> 2014-10-28 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.
> ---
> gdb/ChangeLog | 16 ++++++
> gdb/amd64-linux-tdep.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 164 insertions(+)
>
> diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
> index edbb1b3..9fe68b9 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
> --
> 1.7.10.4
@@ -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