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Avoid QEMU specific types in trace probes

PATCH Applied Daniel P. Berrangé 2 participants 4 messages Mar 8, 2018 – Mar 9, 2018

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Daniel P. Berrangé

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#0 lore raw

v2 cover Avoid QEMU specific types in trace probes

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(-)
Signature · 1 line
2.14.3
author
#1 lore raw

PATCH v2 1/2 trace: remove use of QEMU specific types from trace probes

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 <[email protected]>
---
 trace-events | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
trace-events +3 -3
index 89fcad0fd1..855b0ab240 100644
@@ -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"
Signature · 1 line
2.14.3
author
#2 lore raw

PATCH v2 2/2 trace: only permit standard C types and fixed size integer types

In reply to 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 <[email protected]>
---
 scripts/tracetool/__init__.py | 46 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
scripts/tracetool/__init__.py +46 -0
index 4236062650..b20fac34a3 100644
@@ -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)
Signature · 1 line
2.14.3
Applied
#3 lore raw
In reply to Daniel P. Berrangé
Quoted 5 lines · Daniel P. Berrangé

Changed in v2:

- Split into 2 patches
- Added ptrdiff_t type to whitelist

Quoted 11 lines

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(-)
Signature · 1 line
2.14.3

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

Stefan