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Use a C wrapper for trap() instead of checking and calling the DTrace trap

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hook in assembly.

Suggested by:	kib
Reviewed by:	kib (original version)
X-MFC-With:	r268600
This commit is contained in:
Mark Johnston 2014-07-19 02:27:31 +00:00
parent bef4f148b1
commit 5a5f9d21dd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=268869
4 changed files with 24 additions and 24 deletions
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19
sys/amd64/amd64/exception.S
View File

@ -228,24 +228,7 @@ 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
#ifdef KDTRACE_HOOKS
skiptrap:
#endif
call trap_check
MEXITCOUNT
jmp doreti /* Handle any pending ASTs */

16
sys/amd64/amd64/trap.c
View File

@ -97,7 +97,8 @@ PMC_SOFT_DEFINE( , , page_fault, write);
#include <sys/dtrace_bsd.h>
#endif
extern void trap(struct trapframe *frame);
extern void __noinline trap(struct trapframe *frame);
extern void trap_check(struct trapframe *frame);
extern void syscall(struct trapframe *frame);
void dblfault_handler(struct trapframe *frame);
@ -604,6 +605,19 @@ trap(struct trapframe *frame)
return;
}
/*
* Ensure that we ignore any DTrace-induced faults. This function cannot
* be instrumented, so it cannot generate such faults itself.
*/
void
trap_check(struct trapframe *frame)
{
if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame))
return;
trap(frame);
}
static int
trap_pfault(frame, usermode)
struct trapframe *frame;

4
sys/cddl/dev/dtrace/amd64/dtrace_subr.c
View File

@ -462,9 +462,7 @@ dtrace_gethrestime(void)
return (current_time.tv_sec * 1000000000ULL + current_time.tv_nsec);
}
/*
* Function to handle DTrace traps during probes. See amd64/amd64/exception.S.
*/
/* Function to handle DTrace traps during probes. See amd64/amd64/trap.c. */
int
dtrace_trap(struct trapframe *frame)
{

9
sys/cddl/dev/fbt/fbt.c
View File

@ -232,13 +232,18 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
int size;
u_int8_t *instr, *limit;
if (strncmp(name, "dtrace_", 7) == 0 &&
strncmp(name, "dtrace_safe_", 12) != 0) {
if ((strncmp(name, "dtrace_", 7) == 0 &&
strncmp(name, "dtrace_safe_", 12) != 0) ||
strcmp(name, "trap_check") == 0) {
/*
* Anything beginning with "dtrace_" may be called
* from probe context unless it explicitly indicates
* that it won't be called from probe context by
* using the prefix "dtrace_safe_".
*
* Additionally, we avoid instrumenting trap_check() to avoid
* the possibility of generating a fault in probe context before
* DTrace's fault handler is called.
*/
return (0);
}