Re: svn commit: r268600 - in head/sys: amd64/amd64
--CPxrXXhckaW0WC23
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On Mon, Jul 14, 2014 at 04:38:17AM +0000, Mark Johnston wrote:
> Author: markj
> Date: Mon Jul 14 04:38:17 2014
> New Revision: 268600
> URL: http://svnweb.freebsd.org/changeset/base/268600
>=20
> Log:
> Invoke the DTrace trap handler before calling trap() on amd64. This mat=
ches
> the upstream implementation and helps ensure that a trap induced by tra=
cing
> fbt::trap:entry is handled without recursively generating another trap.
> =20
> This makes it possible to run most (but not all) of the DTrace tests un=
der
> common/safety/ without triggering a kernel panic.
> =20
> Submitted by: Anton Rang <anton.rang@isilon.com> (original version)
> Phabric: D95
>=20
> Modified:
> head/sys/amd64/amd64/exception.S
> head/sys/amd64/amd64/trap.c
> head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c
> head/sys/cddl/dev/dtrace/i386/dtrace_subr.c
> head/sys/cddl/dev/dtrace/mips/dtrace_subr.c
> head/sys/cddl/dev/dtrace/powerpc/dtrace_subr.c
> head/sys/i386/i386/trap.c
> head/sys/mips/mips/trap.c
> head/sys/powerpc/aim/trap.c
> head/sys/sys/dtrace_bsd.h
>=20
> Modified: head/sys/amd64/amd64/exception.S
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/amd64/amd64/exception.S Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/amd64/amd64/exception.S Mon Jul 14 04:38:17 2014 (r268600)
> @@ -228,7 +228,24 @@ alltraps_pushregs_no_rdi:
> .type calltrap,@function
> calltrap:
> movq %rsp,%rdi
> +#ifdef KDTRACE_HOOKS
> + /*
> + * Give DTrace a chance to vet this trap and skip the call to trap() if
> + * it turns out that it was caused by a DTrace probe.
> + */
> + movq dtrace_trap_func,%rax
> + testq %rax,%rax
> + je skiphook
> + call *%rax
> + testq %rax,%rax
> + jne skiptrap
> + movq %rsp,%rdi
> +skiphook:
> +#endif
> call trap
Why is this fragment done in asm ? I see it relatively easy to
either move to the start of trap(), or create a new wrapper around
current trap() which calls dtrace_trap_func conditionally, and then
resorts to the old trap.
> +#ifdef KDTRACE_HOOKS
> +skiptrap:
> +#endif
> MEXITCOUNT
> jmp doreti /* Handle any pending ASTs */
> =20
>=20
> Modified: head/sys/amd64/amd64/trap.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/amd64/amd64/trap.c Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/amd64/amd64/trap.c Mon Jul 14 04:38:17 2014 (r268600)
> @@ -218,18 +218,6 @@ trap(struct trapframe *frame)
> goto out;
> }
> =20
> -#ifdef KDTRACE_HOOKS
> - /*
> - * A trap can occur while DTrace executes a probe. Before
> - * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in its per-cpu flags to indicate that it doesn't
> - * want to fault. On returning from the probe, the no-fault
> - * flag is cleared and finally re-scheduling is enabled.
> - */
> - if (dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(frame, type))
> - goto out;
> -#endif
> -
> if ((frame->tf_rflags & PSL_I) =3D=3D 0) {
> /*
> * Buggy application or kernel code has disabled
>=20
> Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Mon Jul 14 00:16:49 2014=
(r268599)
> +++ head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Mon Jul 14 04:38:17 2014=
(r268600)
> @@ -462,29 +462,27 @@ dtrace_gethrestime(void)
> return (current_time.tv_sec * 1000000000ULL + current_time.tv_nsec);
> }
> =20
> -/* Function to handle DTrace traps during probes. See amd64/amd64/trap.c=
*/
> +/*
> + * Function to handle DTrace traps during probes. See amd64/amd64/except=
ion.S.
> + */
> int
> -dtrace_trap(struct trapframe *frame, u_int type)
> +dtrace_trap(struct trapframe *frame)
> {
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> * Check if DTrace has enabled 'no-fault' mode:
> - *
> */
> if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) !=3D 0) {
> /*
> * There are only a couple of trap types that are expected.
> * All the rest will be handled in the usual way.
> */
> - switch (type) {
> - /* Privilieged instruction fault. */
> - case T_PRIVINFLT:
> - break;
> + switch (frame->tf_trapno) {
> /* General protection fault. */
> case T_PROTFLT:
> /* Flag an illegal operation. */
>=20
> Modified: head/sys/cddl/dev/dtrace/i386/dtrace_subr.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Mon Jul 14 00:16:49 2014 =
(r268599)
> +++ head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Mon Jul 14 04:38:17 2014 =
(r268600)
> @@ -473,24 +473,23 @@ dtrace_gethrestime(void)
> =20
> /* Function to handle DTrace traps during probes. See i386/i386/trap.c */
> int
> -dtrace_trap(struct trapframe *frame, u_int type)
> +dtrace_trap(struct trapframe *frame)
> {
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> * Check if DTrace has enabled 'no-fault' mode:
> - *
> */
> if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) !=3D 0) {
> /*
> * There are only a couple of trap types that are expected.
> * All the rest will be handled in the usual way.
> */
> - switch (type) {
> + switch (frame->tf_trapno) {
> /* General protection fault. */
> case T_PROTFLT:
> /* Flag an illegal operation. */
>=20
> Modified: head/sys/cddl/dev/dtrace/mips/dtrace_subr.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/cddl/dev/dtrace/mips/dtrace_subr.c Mon Jul 14 00:16:49 2014 =
(r268599)
> +++ head/sys/cddl/dev/dtrace/mips/dtrace_subr.c Mon Jul 14 04:38:17 2014 =
(r268600)
> @@ -137,17 +137,20 @@ dtrace_gethrestime(void)
> =20
> /* Function to handle DTrace traps during probes. See amd64/amd64/trap.c=
*/
> int
> -dtrace_trap(struct trapframe *frame, u_int type)
> +dtrace_trap(struct trapframe *frame)
> {
> + u_int type;
> +
> + type =3D (trapframe->cause & MIPS_CR_EXC_CODE) >> MIPS_CR_EXC_CODE_SHIF=
T;
> +
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> * Check if DTrace has enabled 'no-fault' mode:
> - *
> */
> if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) !=3D 0) {
> /*
>=20
> Modified: head/sys/cddl/dev/dtrace/powerpc/dtrace_subr.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/cddl/dev/dtrace/powerpc/dtrace_subr.c Mon Jul 14 00:16:49 20=
14 (r268599)
> +++ head/sys/cddl/dev/dtrace/powerpc/dtrace_subr.c Mon Jul 14 04:38:17 20=
14 (r268600)
> @@ -262,24 +262,23 @@ dtrace_gethrestime(void)
> =20
> /* Function to handle DTrace traps during probes. See powerpc/powerpc/tr=
ap.c */
> int
> -dtrace_trap(struct trapframe *frame, u_int type)
> +dtrace_trap(struct trapframe *frame)
> {
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> * Check if DTrace has enabled 'no-fault' mode:
> - *
> */
> if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) !=3D 0) {
> /*
> * There are only a couple of trap types that are expected.
> * All the rest will be handled in the usual way.
> */
> - switch (type) {
> + switch (frame->exc) {
> /* Page fault. */
> case EXC_DSI:
> case EXC_DSE:
>=20
> Modified: head/sys/i386/i386/trap.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/i386/i386/trap.c Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/i386/i386/trap.c Mon Jul 14 04:38:17 2014 (r268600)
> @@ -246,7 +246,7 @@ trap(struct trapframe *frame)
> * flag is cleared and finally re-scheduling is enabled.
> */
> if ((type =3D=3D T_PROTFLT || type =3D=3D T_PAGEFLT) &&
> - dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(frame, type))
> + dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(frame))
> goto out;
> #endif
> =20
>=20
> Modified: head/sys/mips/mips/trap.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/mips/mips/trap.c Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/mips/mips/trap.c Mon Jul 14 04:38:17 2014 (r268600)
> @@ -605,7 +605,7 @@ trap(struct trapframe *trapframe)
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> @@ -618,7 +618,7 @@ trap(struct trapframe *trapframe)
> * XXXDTRACE: add pid probe handler here (if ever)
> */
> if (!usermode) {
> - if (dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(trapframe, type))
> + if (dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(trapframe))
> return (trapframe->pc);
> }
> #endif
>=20
> Modified: head/sys/powerpc/aim/trap.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/powerpc/aim/trap.c Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/powerpc/aim/trap.c Mon Jul 14 04:38:17 2014 (r268600)
> @@ -167,7 +167,7 @@ trap(struct trapframe *frame)
> /*
> * A trap can occur while DTrace executes a probe. Before
> * executing the probe, DTrace blocks re-scheduling and sets
> - * a flag in it's per-cpu flags to indicate that it doesn't
> + * a flag in its per-cpu flags to indicate that it doesn't
> * want to fault. On returning from the probe, the no-fault
> * flag is cleared and finally re-scheduling is enabled.
> *
> @@ -176,7 +176,7 @@ trap(struct trapframe *frame)
> * handled the trap and modified the trap frame so that this
> * function can return normally.
> */
> - if (dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(frame, type))
> + if (dtrace_trap_func !=3D NULL && (*dtrace_trap_func)(frame))
> return;
> #endif
> =20
>=20
> Modified: head/sys/sys/dtrace_bsd.h
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/sys/dtrace_bsd.h Mon Jul 14 00:16:49 2014 (r268599)
> +++ head/sys/sys/dtrace_bsd.h Mon Jul 14 04:38:17 2014 (r268600)
> @@ -48,15 +48,14 @@ extern cyclic_clock_func_t cyclic_clock_
> =20
> void clocksource_cyc_set(const struct bintime *t);
> =20
> +int dtrace_trap(struct trapframe *);
> +
> /*
> * The dtrace module handles traps that occur during a DTrace probe.
> * This type definition is used in the trap handler to provide a
> - * hook for the dtrace module to register it's handler with.
> + * hook for the dtrace module to register its handler with.
> */
> -typedef int (*dtrace_trap_func_t)(struct trapframe *, u_int);
> -
> -int dtrace_trap(struct trapframe *, u_int);
> -
> +typedef int (*dtrace_trap_func_t)(struct trapframe *);
> extern dtrace_trap_func_t dtrace_trap_func;
> =20
> /*
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