Author: kib
Date: Wed Nov 9 18:25:50 2011
New Revision: 227399
URL: http://svn.freebsd.org/changeset/base/227399
Log:
Attempt to improve formatting and content of several comments for
amd64 and i386 MD code.
Based on suggestions by: bde
MFC after: 1 week
Modified:
head/sys/amd64/amd64/trap.c
head/sys/amd64/include/signal.h
head/sys/amd64/include/ucontext.h
head/sys/i386/i386/trap.c
head/sys/i386/include/signal.h
head/sys/i386/include/ucontext.h
Modified: head/sys/amd64/amd64/trap.c
==============================================================================
--- head/sys/amd64/amd64/trap.c Wed Nov 9 18:24:20 2011 (r227398)
+++ head/sys/amd64/amd64/trap.c Wed Nov 9 18:25:50 2011 (r227399)
@@ -900,9 +900,9 @@ cpu_fetch_syscall_args(struct thread *td
#include "../../kern/subr_syscall.c"
/*
- * syscall - system call request C handler
- *
- * A system call is essentially treated as a trap.
+ * System call handler for native binaries. The trap frame is already
+ * set up by the assembler trampoline and a pointer to it is saved in
+ * td_frame.
*/
void
amd64_syscall(struct thread *td, int traced)
Modified: head/sys/amd64/include/signal.h
==============================================================================
--- head/sys/amd64/include/signal.h Wed Nov 9 18:24:20 2011
(r227398)
+++ head/sys/amd64/include/signal.h Wed Nov 9 18:25:50 2011
(r227399)
@@ -47,18 +47,14 @@ typedef long sig_atomic_t;
#include <machine/trap.h> /* codes for SIGILL, SIGFPE */
/*
- * Only the kernel should need these old type definitions.
- */
-/*
* Information pushed on stack when a signal is delivered.
* This is used by the kernel to restore state following
* execution of the signal handler. It is also made available
* to the handler to allow it to restore state properly if
* a non-standard exit is performed.
- */
-/*
- * The sequence of the fields/registers in struct sigcontext should match
- * those in mcontext_t.
+ *
+ * The sequence of the fields/registers after sc_mask in struct
+ * sigcontext must match those in mcontext_t and struct trapframe.
*/
struct sigcontext {
struct __sigset sc_mask; /* signal mask to restore */
@@ -93,8 +89,8 @@ struct sigcontext {
long sc_ss;
long sc_len; /* sizeof(mcontext_t) */
/*
- * XXX - See <machine/ucontext.h> and <machine/fpu.h> for
- * the following fields.
+ * See <machine/ucontext.h> and <machine/fpu.h> for the following
+ * fields.
*/
long sc_fpformat;
long sc_ownedfp;
Modified: head/sys/amd64/include/ucontext.h
==============================================================================
--- head/sys/amd64/include/ucontext.h Wed Nov 9 18:24:20 2011
(r227398)
+++ head/sys/amd64/include/ucontext.h Wed Nov 9 18:25:50 2011
(r227399)
@@ -41,12 +41,13 @@
typedef struct __mcontext {
/*
- * The first 24 fields must match the definition of
- * sigcontext. So that we can support sigcontext
- * and ucontext_t at the same time.
+ * The definition of mcontext_t must match the layout of
+ * struct sigcontext after the sc_mask member. This is so
+ * that we can support sigcontext and ucontext_t at the same
+ * time.
*/
- __register_t mc_onstack; /* XXX - sigcontext compat. */
- __register_t mc_rdi; /* machine state (struct
trapframe) */
+ __register_t mc_onstack; /* XXX - sigcontext compat. */
+ __register_t mc_rdi; /* machine state (struct trapframe) */
__register_t mc_rsi;
__register_t mc_rdx;
__register_t mc_rcx;
Modified: head/sys/i386/i386/trap.c
==============================================================================
--- head/sys/i386/i386/trap.c Wed Nov 9 18:24:20 2011 (r227398)
+++ head/sys/i386/i386/trap.c Wed Nov 9 18:25:50 2011 (r227399)
@@ -1065,9 +1065,8 @@ cpu_fetch_syscall_args(struct thread *td
#include "../../kern/subr_syscall.c"
/*
- * syscall - system call request C handler
- *
- * A system call is essentially treated as a trap.
+ * syscall - system call request C handler. A system call is
+ * essentially treated as a trap by reusing the frame layout.
*/
void
syscall(struct trapframe *frame)
Modified: head/sys/i386/include/signal.h
==============================================================================
--- head/sys/i386/include/signal.h Wed Nov 9 18:24:20 2011
(r227398)
+++ head/sys/i386/include/signal.h Wed Nov 9 18:25:50 2011
(r227399)
@@ -46,16 +46,17 @@ typedef int sig_atomic_t;
#include <machine/trap.h> /* codes for SIGILL, SIGFPE */
/*
- * Only the kernel should need these old type definitions.
- */
-#if defined(_KERNEL) && defined(COMPAT_43)
-/*
* Information pushed on stack when a signal is delivered.
* This is used by the kernel to restore state following
* execution of the signal handler. It is also made available
* to the handler to allow it to restore state properly if
* a non-standard exit is performed.
*/
+
+#if defined(_KERNEL) && defined(COMPAT_43)
+/*
+ * Only the kernel should need these old type definitions.
+ */
struct osigcontext {
int sc_onstack; /* sigstack state to restore */
osigset_t sc_mask; /* signal mask to restore */
@@ -83,7 +84,7 @@ struct osigcontext {
/*
* The sequence of the fields/registers in struct sigcontext should match
- * those in mcontext_t.
+ * those in mcontext_t and struct trapframe.
*/
struct sigcontext {
struct __sigset sc_mask; /* signal mask to restore */
@@ -109,8 +110,8 @@ struct sigcontext {
int sc_ss;
int sc_len; /* sizeof(mcontext_t) */
/*
- * XXX - See <machine/ucontext.h> and <machine/npx.h> for
- * the following fields.
+ * See <machine/ucontext.h> and <machine/npx.h> for
+ * the following fields.
*/
int sc_fpformat;
int sc_ownedfp;
Modified: head/sys/i386/include/ucontext.h
==============================================================================
--- head/sys/i386/include/ucontext.h Wed Nov 9 18:24:20 2011
(r227398)
+++ head/sys/i386/include/ucontext.h Wed Nov 9 18:25:50 2011
(r227399)
@@ -33,9 +33,9 @@
typedef struct __mcontext {
/*
- * The first 20 fields must match the definition of
- * sigcontext. So that we can support sigcontext
- * and ucontext_t at the same time.
+ * The definition of mcontext_t shall match the layout of
+ * struct sigcontext after the sc_mask member. So that we can
+ * support sigcontext and ucontext_t at the same time.
*/
__register_t mc_onstack; /* XXX - sigcontext compat. */
__register_t mc_gs; /* machine state (struct trapframe) */
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