331744 - trace-malloc does not work on x86_64 linux

Status: RESOLVED WORKSFORME

(Core :: XPCOM, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

trace-malloc doesn't work for me on x86_64 Linux (Fedora Core 5), because the way we define a malloc whose goal is to override the malloc in glibc doesn't actually seem to override the one in glibc.  I asked Ulrich Drepper about this, and he said (as I expected) that the functions in glibc are designed so that you can do this, and didn't know why it wouldn't be working.

(Working on x86_64 also depends on being 64-bit clean, bug 331743.)

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Turns out 4 changes of the form:

-__ptr_t malloc(size_t size)
+NS_EXTERNAL_VIS_(__ptr_t)
+malloc(size_t size)

get the callbacks called.  Not sure why this is different between i386 and x86_64, though.

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

This might actually not be x86_64 specific.  I may have just had different visibility options in the two builds.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I've put the patch for this within my patch on bug 331743.

Comment 4

[Karl Tomlinson (:karlt)]

We need a better stackwalk.