Paul Rosenfeld has submitted this change and it was merged. (
https://gem5-review.googlesource.com/2640 )
Change subject: arm,sim: fix context switch stats dumps for ARM64/Linux
......................................................................
arm,sim: fix context switch stats dumps for ARM64/Linux
32bit and 64bit Linux have different arguments passed to the
__switch_to() function that gem5 hooks into in order to collect context
switch statistics. 64bit Linux provides the task_struct pointer to the
next task that will be switched to, which means we don't have to look
up the task_struct from thread_info as we do in 32bit ARM Linux.
This patch adds a second set of accessors to ThreadInfo to extract
details such as the pid, tgid, task name, etc., directly from a
task_struct. The existing accessors maintain their existing behavior by
first looking up the task_struct and then calling these new accessors.
A 64-bit variant of the DumpStatsPCEvent class is added that uses these
new accessors to get the task details for the context switch dumps
directly from the task_struct passed to __switch_to().
Change-Id: I63c4b3e1ad64446751a91f6340901d5180d7382d
Reviewed-on: https://gem5-review.googlesource.com/2640
Reviewed-by: Curtis Dunham <curtis.dun...@arm.com>
Reviewed-by: Jason Lowe-Power <ja...@lowepower.com>
Reviewed-by: Pau Cabre <pau.ca...@metempsy.com>
Reviewed-by: Andreas Sandberg <andreas.sandb...@arm.com>
Maintainer: Andreas Sandberg <andreas.sandb...@arm.com>
---
M src/arch/arm/linux/system.cc
M src/arch/arm/linux/system.hh
M src/arch/generic/linux/threadinfo.hh
3 files changed, 116 insertions(+), 24 deletions(-)
Approvals:
Jason Lowe-Power: Looks good to me, but someone else must approve
Andreas Sandberg: Looks good to me, approved; Looks good to me, approved
Curtis Dunham: Looks good to me, but someone else must approve
Pau Cabre: Looks good to me, but someone else must approve
diff --git a/src/arch/arm/linux/system.cc b/src/arch/arm/linux/system.cc
index 52e075d..7f06475 100644
--- a/src/arch/arm/linux/system.cc
+++ b/src/arch/arm/linux/system.cc
@@ -236,7 +236,14 @@
LinuxArmSystem::startup()
{
if (enableContextSwitchStatsDump) {
- dumpStatsPCEvent =
addKernelFuncEvent<DumpStatsPCEvent>("__switch_to");
+ if (!highestELIs64()) {
+ dumpStatsPCEvent =
+ addKernelFuncEvent<DumpStatsPCEvent>("__switch_to");
+ } else {
+ dumpStatsPCEvent =
+ addKernelFuncEvent<DumpStatsPCEvent64>("__switch_to");
+ }
+
if (!dumpStatsPCEvent)
panic("dumpStatsPCEvent not created!");
@@ -276,25 +283,64 @@
Linux::dumpDmesg(getThreadContext(0), std::cout);
}
-/** This function is called whenever the the kernel function
- * "__switch_to" is called to change running tasks.
+/**
+ * Extracts the information used by the DumpStatsPCEvent by reading the
+ * thread_info pointer passed to __switch_to() in 32 bit ARM Linux
*
* r0 = task_struct of the previously running process
- * r1 = task_info of the previously running process
- * r2 = task_info of the next process to run
+ * r1 = thread_info of the previously running process
+ * r2 = thread_info of the next process to run
+ */
+void
+DumpStatsPCEvent::getTaskDetails(ThreadContext *tc, uint32_t &pid,
+ uint32_t &tgid, std::string &next_task_str, int32_t &mm) {
+
+ Linux::ThreadInfo ti(tc);
+ Addr task_descriptor = tc->readIntReg(2);
+ pid = ti.curTaskPID(task_descriptor);
+ tgid = ti.curTaskTGID(task_descriptor);
+ next_task_str = ti.curTaskName(task_descriptor);
+
+ // Streamline treats pid == -1 as the kernel process.
+ // Also pid == 0 implies idle process (except during Linux boot)
+ mm = ti.curTaskMm(task_descriptor);
+}
+
+/**
+ * Extracts the information used by the DumpStatsPCEvent64 by reading the
+ * task_struct pointer passed to __switch_to() in 64 bit ARM Linux
+ *
+ * r0 = task_struct of the previously running process
+ * r1 = task_struct of next process to run
+ */
+void
+DumpStatsPCEvent64::getTaskDetails(ThreadContext *tc, uint32_t &pid,
+ uint32_t &tgid, std::string &next_task_str, int32_t &mm) {
+
+ Linux::ThreadInfo ti(tc);
+ Addr task_struct = tc->readIntReg(1);
+ pid = ti.curTaskPIDFromTaskStruct(task_struct);
+ tgid = ti.curTaskTGIDFromTaskStruct(task_struct);
+ next_task_str = ti.curTaskNameFromTaskStruct(task_struct);
+
+ // Streamline treats pid == -1 as the kernel process.
+ // Also pid == 0 implies idle process (except during Linux boot)
+ mm = ti.curTaskMmFromTaskStruct(task_struct);
+}
+
+/** This function is called whenever the the kernel function
+ * "__switch_to" is called to change running tasks.
*/
void
DumpStatsPCEvent::process(ThreadContext *tc)
{
- Linux::ThreadInfo ti(tc);
- Addr task_descriptor = tc->readIntReg(2);
- uint32_t pid = ti.curTaskPID(task_descriptor);
- uint32_t tgid = ti.curTaskTGID(task_descriptor);
- std::string next_task_str = ti.curTaskName(task_descriptor);
+ uint32_t pid = 0;
+ uint32_t tgid = 0;
+ std::string next_task_str;
+ int32_t mm = 0;
- // Streamline treats pid == -1 as the kernel process.
- // Also pid == 0 implies idle process (except during Linux boot)
- int32_t mm = ti.curTaskMm(task_descriptor);
+ getTaskDetails(tc, pid, tgid, next_task_str, mm);
+
bool is_kernel = (mm == 0);
if (is_kernel && (pid != 0)) {
pid = -1;
diff --git a/src/arch/arm/linux/system.hh b/src/arch/arm/linux/system.hh
index 709776f..247ebae 100644
--- a/src/arch/arm/linux/system.hh
+++ b/src/arch/arm/linux/system.hh
@@ -132,6 +132,20 @@
{}
virtual void process(ThreadContext* tc);
+ protected:
+ virtual void getTaskDetails(ThreadContext *tc, uint32_t &pid,
+ uint32_t &tgid, std::string &next_task_str, int32_t &mm);
+
+};
+
+class DumpStatsPCEvent64 : public DumpStatsPCEvent {
+ public:
+ DumpStatsPCEvent64(PCEventQueue *q, const std::string &desc, Addr addr)
+ : DumpStatsPCEvent(q, desc, addr)
+ {}
+ private:
+ void getTaskDetails(ThreadContext *tc, uint32_t &pid, uint32_t &tgid,
+ std::string &next_task_str, int32_t &mm) override;
};
diff --git a/src/arch/generic/linux/threadinfo.hh
b/src/arch/generic/linux/threadinfo.hh
index 6a5d031..89db36a 100644
--- a/src/arch/generic/linux/threadinfo.hh
+++ b/src/arch/generic/linux/threadinfo.hh
@@ -95,6 +95,9 @@
inline Addr
curTaskInfo(Addr thread_info = 0)
{
+ // Note that in Linux 4.10 the thread_info struct will no longer
have a
+ // pointer to the task_struct for arm64. See:
+ // https://patchwork.kernel.org/patch/9333699/
int32_t offset;
if (!get_data("thread_info_task", offset))
return 0;
@@ -109,33 +112,44 @@
}
int32_t
- curTaskPID(Addr thread_info = 0)
- {
+ curTaskPIDFromTaskStruct(Addr task_struct) {
int32_t offset;
if (!get_data("task_struct_pid", offset))
return -1;
int32_t pid;
- CopyOut(tc, &pid, curTaskInfo(thread_info) + offset, sizeof(pid));
+ CopyOut(tc, &pid, task_struct + offset, sizeof(pid));
return pid;
}
int32_t
- curTaskTGID(Addr thread_info = 0)
+ curTaskPID(Addr thread_info = 0)
+ {
+ return curTaskPIDFromTaskStruct(curTaskInfo(thread_info));
+ }
+
+ int32_t
+ curTaskTGIDFromTaskStruct(Addr task_struct)
{
int32_t offset;
if (!get_data("task_struct_tgid", offset))
return -1;
int32_t tgid;
- CopyOut(tc, &tgid, curTaskInfo(thread_info) + offset,
sizeof(tgid));
+ CopyOut(tc, &tgid, task_struct + offset, sizeof(tgid));
return tgid;
}
+ int32_t
+ curTaskTGID(Addr thread_info = 0)
+ {
+ return curTaskTGIDFromTaskStruct(curTaskInfo(thread_info));
+ }
+
int64_t
- curTaskStart(Addr thread_info = 0)
+ curTaskStartFromTaskStruct(Addr task_struct)
{
int32_t offset;
if (!get_data("task_struct_start_time", offset))
@@ -144,13 +158,19 @@
int64_t data;
// start_time is actually of type timespec, but if we just
// grab the first long, we'll get the seconds out of it
- CopyOut(tc, &data, curTaskInfo(thread_info) + offset,
sizeof(data));
+ CopyOut(tc, &data, task_struct + offset, sizeof(data));
return data;
}
+ int64_t
+ curTaskStart(Addr thread_info = 0)
+ {
+ return curTaskStartFromTaskStruct(curTaskInfo(thread_info));
+ }
+
std::string
- curTaskName(Addr thread_info = 0)
+ curTaskNameFromTaskStruct(Addr task_struct)
{
int32_t offset;
int32_t size;
@@ -162,23 +182,35 @@
return "FailureIn_curTaskName";
char buffer[size + 1];
- CopyStringOut(tc, buffer, curTaskInfo(thread_info) + offset, size);
+ CopyStringOut(tc, buffer, task_struct + offset, size);
return buffer;
}
+ std::string
+ curTaskName(Addr thread_info = 0)
+ {
+ return curTaskNameFromTaskStruct(curTaskInfo(thread_info));
+ }
+
int32_t
- curTaskMm(Addr thread_info = 0)
+ curTaskMmFromTaskStruct(Addr task_struct)
{
int32_t offset;
if (!get_data("task_struct_mm", offset))
return -1;
int32_t mm_ptr;
- CopyOut(tc, &mm_ptr, curTaskInfo(thread_info) + offset,
sizeof(mm_ptr));
+ CopyOut(tc, &mm_ptr, task_struct + offset, sizeof(mm_ptr));
return mm_ptr;
}
+
+ int32_t
+ curTaskMm(Addr thread_info = 0)
+ {
+ return curTaskMmFromTaskStruct(curTaskInfo(thread_info));
+ }
};
} // namespace Linux
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I63c4b3e1ad64446751a91f6340901d5180d7382d
Gerrit-Change-Number: 2640
Gerrit-PatchSet: 3
Gerrit-Owner: Paul Rosenfeld <prosenf...@micron.com>
Gerrit-Reviewer: Andreas Sandberg <andreas.sandb...@arm.com>
Gerrit-Reviewer: Curtis Dunham <curtis.dun...@arm.com>
Gerrit-Reviewer: Jason Lowe-Power <ja...@lowepower.com>
Gerrit-Reviewer: Nikos Nikoleris <nikos.nikole...@arm.com>
Gerrit-Reviewer: Pau Cabre <pau.ca...@metempsy.com>
Gerrit-Reviewer: Paul Rosenfeld <prosenf...@micron.com>
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