[Qemu-devel] [PATCH v2 0/2] Avoid QEMU specific types in trace probes

[Qemu-devel] [PATCH v2 0/2] Avoid QEMU specific types in trace probes

[Daniel P. Berrangé]

Changed in v2:

 - Split into 2 patches
 - Added ptrdiff_t type to whitelist

Daniel P. Berrangé (2):
  trace: remove use of QEMU specific types from trace probes
  trace: only permit standard C types and fixed size integer types

 scripts/tracetool/__init__.py | 46 +++++++++++++++++++++++++++++++++++++++++++
 trace-events                  |  6 +++---
 2 files changed, 49 insertions(+), 3 deletions(-)

-- 
2.14.3

[Qemu-devel] [PATCH v2 1/2] trace: remove use of QEMU specific types from trace probes

[Daniel P. Berrangé]

Any compound structs / unions / etc, should always be declared as
'void *' pointers, since it cannot be assumed that trace backends
are able to resolve QEMU typedefs.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 trace-events | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/trace-events b/trace-events
index 89fcad0fd1..855b0ab240 100644
--- a/trace-events
+++ b/trace-events
@@ -68,9 +68,9 @@ memory_region_tb_read(int cpu_index, uint64_t addr, uint64_t value, unsigned siz
 memory_region_tb_write(int cpu_index, uint64_t addr, uint64_t value, unsigned size) "cpu %d addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
 memory_region_ram_device_read(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
 memory_region_ram_device_write(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
-flatview_new(FlatView *view, MemoryRegion *root) "%p (root %p)"
-flatview_destroy(FlatView *view, MemoryRegion *root) "%p (root %p)"
-flatview_destroy_rcu(FlatView *view, MemoryRegion *root) "%p (root %p)"
+flatview_new(void *view, void *root) "%p (root %p)"
+flatview_destroy(void *view, void *root) "%p (root %p)"
+flatview_destroy_rcu(void *view, void *root) "%p (root %p)"
 
 # gdbstub.c
 gdbstub_op_start(const char *device) "Starting gdbstub using device %s"
-- 
2.14.3

[Qemu-devel] [PATCH v2 2/2] trace: only permit standard C types and fixed size integer types

[Daniel P. Berrangé]

Some trace backends will compile code based on the declared trace
events. It should not be assumed that the backends can resolve any QEMU
specific typedefs. So trace events should restrict their argument
types to the standard C types and fixed size integer types. Any complex
pointer types can be declared as "void *" for purposes of trace events,
since nothing will be dereferencing these pointer arguments.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 scripts/tracetool/__init__.py | 46 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index 4236062650..b20fac34a3 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -41,6 +41,51 @@ def out(*lines, **kwargs):
     lines = [ l % kwargs for l in lines ]
     sys.stdout.writelines("\n".join(lines) + "\n")
 
+# We only want to allow standard C types or fixed sized
+# integer types. We don't want QEMU specific types
+# as we can't assume trace backends can resolve all the
+# typedefs
+ALLOWED_TYPES = [
+    "int",
+    "long",
+    "short",
+    "char",
+    "bool",
+    "unsigned",
+    "signed",
+    "float",
+    "double",
+    "int8_t",
+    "uint8_t",
+    "int16_t",
+    "uint16_t",
+    "int32_t",
+    "uint32_t",
+    "int64_t",
+    "uint64_t",
+    "void",
+    "size_t",
+    "ssize_t",
+    "uintptr_t",
+    "ptrdiff_t",
+    # Magic substitution is done by tracetool
+    "TCGv",
+]
+
+def validate_type(name):
+    bits = name.split(" ")
+    for bit in bits:
+        bit = re.sub("\*", "", bit)
+        if bit == "":
+            continue
+        if bit == "const":
+            continue
+        if bit not in ALLOWED_TYPES:
+            raise ValueError("Argument type '%s' is not in whitelist. "
+                             "Only standard C types and fixed size integer "
+                             "types should be used. struct, union, and "
+                             "other complex pointer types should be "
+                             "declared as 'void *'" % name)
 
 class Arguments:
     """Event arguments description."""
@@ -87,6 +132,7 @@ class Arguments:
             else:
                 arg_type, identifier = arg.rsplit(None, 1)
 
+            validate_type(arg_type)
             res.append((arg_type, identifier))
         return Arguments(res)
 
-- 
2.14.3

Re: [Qemu-devel] [PATCH v2 0/2] Avoid QEMU specific types in trace probes

[Stefan Hajnoczi]

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On Thu, Mar 08, 2018 at 03:55:22PM +0000, Daniel P. Berrangé wrote:
> Changed in v2:
> 
>  - Split into 2 patches
>  - Added ptrdiff_t type to whitelist
> 
> Daniel P. Berrangé (2):
>   trace: remove use of QEMU specific types from trace probes
>   trace: only permit standard C types and fixed size integer types
> 
>  scripts/tracetool/__init__.py | 46 +++++++++++++++++++++++++++++++++++++++++++
>  trace-events                  |  6 +++---
>  2 files changed, 49 insertions(+), 3 deletions(-)
> 
> -- 
> 2.14.3
> 

Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing

Stefan

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