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authormarkj <markj@FreeBSD.org>2013-11-05 03:23:54 +0000
committermarkj <markj@FreeBSD.org>2013-11-05 03:23:54 +0000
commit3250f228876dac940ab67d0ed1b0f3d5878935ce (patch)
tree10bceb6d070bc2cf3786ddfda15e065221bd9194
parentb41cdbed2449cb7c863eb6c20c8081fc46e5415d (diff)
downloadFreeBSD-src-3250f228876dac940ab67d0ed1b0f3d5878935ce.zip
FreeBSD-src-3250f228876dac940ab67d0ed1b0f3d5878935ce.tar.gz
Modify the libproc breakpoint add/remove functions to stop the target
process if it has not already been stopped, since this is required for ptrace(2) to work. libdtrace does not seem to stop target processes before trying to remove their breakpoints, so we were previously failing to remove the breakpoint on r_debug_state() in rtld. This was causing processes to die with SIGTRAP if they called dlopen(3) after dtrace(1) had detached. Reported by: symbolics@gmx.com Reviewed by: rpaulo MFC after: 1 month
-rw-r--r--lib/libproc/proc_bkpt.c66
1 files changed, 59 insertions, 7 deletions
diff --git a/lib/libproc/proc_bkpt.c b/lib/libproc/proc_bkpt.c
index 1878c7f..2c2761a 100644
--- a/lib/libproc/proc_bkpt.c
+++ b/lib/libproc/proc_bkpt.c
@@ -37,8 +37,9 @@ __FBSDID("$FreeBSD$");
#include <assert.h>
#include <err.h>
-#include <stdio.h>
#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
#include "_libproc.h"
#if defined(__i386__) || defined(__amd64__)
@@ -54,12 +55,39 @@ __FBSDID("$FreeBSD$");
#error "Add support for your architecture"
#endif
+static void
+proc_cont(struct proc_handle *phdl)
+{
+
+ ptrace(PT_CONTINUE, proc_getpid(phdl), (caddr_t)1, 0);
+}
+
+static int
+proc_stop(struct proc_handle *phdl)
+{
+ int status;
+
+ if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
+ DPRINTF("kill %d", proc_getpid(phdl));
+ return (-1);
+ } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
+ DPRINTF("waitpid %d", proc_getpid(phdl));
+ return (-1);
+ } else if (!WIFSTOPPED(status)) {
+ DPRINTFX("waitpid: unexpected status 0x%x", status);
+ return (-1);
+ }
+
+ return (0);
+}
+
int
proc_bkptset(struct proc_handle *phdl, uintptr_t address,
unsigned long *saved)
{
struct ptrace_io_desc piod;
unsigned long paddr, caddr;
+ int ret = 0;
*saved = 0;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
@@ -68,6 +96,12 @@ proc_bkptset(struct proc_handle *phdl, uintptr_t address,
return (-1);
}
+ DPRINTFX("adding breakpoint at 0x%lx", address);
+
+ if (phdl->status != PS_STOP)
+ if (proc_stop(phdl) != 0)
+ return (-1);
+
/*
* Read the original instruction.
*/
@@ -80,7 +114,8 @@ proc_bkptset(struct proc_handle *phdl, uintptr_t address,
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't read instruction at address 0x%"
PRIuPTR, address);
- return (-1);
+ ret = -1;
+ goto done;
}
*saved = paddr;
/*
@@ -95,10 +130,16 @@ proc_bkptset(struct proc_handle *phdl, uintptr_t address,
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%"
PRIuPTR, address);
- return (-1);
+ ret = -1;
+ goto done;
}
- return (0);
+done:
+ if (phdl->status != PS_STOP)
+ /* Restart the process if we had to stop it. */
+ proc_cont(phdl);
+
+ return (ret);
}
int
@@ -107,13 +148,20 @@ proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
{
struct ptrace_io_desc piod;
unsigned long paddr, caddr;
+ int ret = 0;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
- DPRINTFX("removing breakpoint at 0x%lx\n", address);
+
+ DPRINTFX("removing breakpoint at 0x%lx", address);
+
+ if (phdl->status != PS_STOP)
+ if (proc_stop(phdl) != 0)
+ return (-1);
+
/*
* Overwrite the breakpoint instruction that we setup previously.
*/
@@ -126,10 +174,14 @@ proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%"
PRIuPTR, address);
- return (-1);
+ ret = -1;
}
+
+ if (phdl->status != PS_STOP)
+ /* Restart the process if we had to stop it. */
+ proc_cont(phdl);
- return (0);
+ return (ret);
}
/*
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