Re: [PATCH] drop the deprecated malloc/free hooks in hurd/mach-defpager
Hi!
On Tue, 29 Dec 2015 23:09:54 +0100, Flavio Cruz wrote:
> mach-defpager: Drop the deprecated malloc/free hooks.
(After approval by Samuel, this became commit
8c49801c8f7e3f800cabedf8fca8ccec3cf35a22.)
> * mach-defpager/kalloc.c: Define malloc and free directly since those are weak
> symbols.
The idea here is to just change the mechanism (override glibc's weak
symbols instead of using glibc's deprecated malloc hooks), while not
changing any semantics, right?
From a quick look, I have some doubts about this generally (so, not only
related to your change).
> --- a/mach-defpager/kalloc.c
> +++ b/mach-defpager/kalloc.c
> -static void *
> -malloc_hook (size_t size, const void *caller)
> +void *
> +malloc (size_t size)
> {
>return (void *) kalloc ((vm_size_t) size);
> }
>
> -static void
> -free_hook (void *ptr, const void *caller)
> +void
> +free (void *ptr)
> {
>/* Just ignore harmless attempts at cleanliness. */
>/* panic("free not implemented"); */
So, here we now only provide the malloc and free symbols. What happens
if, for example, calloc, realloc, posix_memalign et al. are called?
For example, looking at [glibc]/malloc/malloc.c:__libc_calloc (weak alias
for calloc). Before your change, it called mach-defpager's malloc_hook,
and then zeroed that region. After your change, it is implemented using
the real glibc calloc -- which actually does change the semantics in an
unintended way?
Backing up one step: what is actually being done here in mach-defpager?
Again from just a quick look, is the idea to use wired memory for all of
mach-defpager's process memory?
So, for example, if now some mach-defpager code calls calloc, it will now
get non-wired "glibc" memory instead of wired "kalloc" memory. The
problem here is not mach-defpager's own code (which we can easily
verify/control), but the problems is the libraries it links against,
which currently are: libihash, libpthread, glibc itself, and any
dependencies these may have. Can we be sure these are not internally
using calloc, for example?
Now, this is not a new problem that you introduced ;-) -- previously we
also didn't provide malloc's memalign and realloc hooks, and realloc is
used quite commonly, I suppose?
If my theories are correct, do we need to use a different mechanism to
get the whole mach-defpager process into wired memory?
Grüße
Thomas
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Re: Complete changes to use -L instead of -Wl,-rpath-link (was: [SCM] Hurd branch, master, updated. v0.7-16-gc9c29eb)
Thomas Schwinge, on Mon 16 May 2016 17:00:16 +0200, wrote: > > * Makeconf (rpath): Remove, replaced by... > > (lpath): ... new variable. > > (link-executable, $(libname).so.$(hurd-version)): Use $(lpath) instead > > of > > $(rpath). > > Please verify these additional changes -- you probably just missed these > by accident? Very probably, yes. Samuel
Complete changes to use -L instead of -Wl, -rpath-link (was: [SCM] Hurd branch, master, updated. v0.7-16-gc9c29eb)
Hi Samuel!
On Sun, 29 Nov 2015 15:49:00 +, Samuel Thibault
wrote:
> commit c9c29eb890527fe68900e4a0af7c2df9a9fa5b40
> Author: Samuel Thibault
> Date: Sun Nov 29 16:47:06 2015 +0100
>
> Use -L instead of -Wl,-rpath-link
>
> The latter does not work for libpthread.a which passes -lihash, which
> would
> find the installed libihash.a instead of the just-compiled one.
>
> * Makeconf (rpath): Remove, replaced by...
> (lpath): ... new variable.
> (link-executable, $(libname).so.$(hurd-version)): Use $(lpath) instead of
> $(rpath).
Please verify these additional changes -- you probably just missed these
by accident?
commit 34071b357d821cc6285ef85d600dfa842252949c
Author: Thomas Schwinge
Date: Mon May 16 16:49:30 2016 +0200
Complete changes to use -L instead of -Wl,-rpath-link
Changes missing from commit c9c29eb890527fe68900e4a0af7c2df9a9fa5b40.
* console-client/Makefile (%.so.$(hurd-version)): Use $(lpath) instead of
$(rpath)
* libstore/Makefile (libstore_%.so.$(hurd-version)): Likewise.
---
console-client/Makefile | 5 +++--
libstore/Makefile | 5 +++--
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git console-client/Makefile console-client/Makefile
index 1784d7c..024a053 100644
--- console-client/Makefile
+++ console-client/Makefile
@@ -1,6 +1,7 @@
#
# Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004,
-# 2005, 2008, 2010 Free Software Foundation, Inc.
+# 2005, 2008, 2010, 2011, 2012, 2013, 2014, 2015, 2016 Free Software
+# Foundation, Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
@@ -91,7 +92,7 @@ $(module-dir)/%: %
# You can use this rule to make a dynamically-loadable version of any
# of the modules.
%.so.$(hurd-version):
- $(CC) -shared -Wl,-soname=$@ -o $@ $(rpath) \
+ $(CC) -shared -Wl,-soname=$@ -o $@ $(lpath) \
$(CFLAGS) $($*-CFLAGS) $(LDFLAGS) \
'-Wl,-(' $($*-LDLIBS) '-Wl,-)' $^
diff --git libstore/Makefile libstore/Makefile
index 28f5660..3ba0017 100644
--- libstore/Makefile
+++ libstore/Makefile
@@ -1,6 +1,7 @@
# Makefile for libstore
#
-# Copyright (C) 1995,96,97,2001,02 Free Software Foundation, Inc.
+# Copyright (C) 1995, 1996, 1997, 1999, 2001, 2002, 2010, 2012, 2013, 2014,
+# 2016 Free Software Foundation, Inc.
# Written by Miles Bader
#
# This file is part of the GNU Hurd.
@@ -73,7 +74,7 @@ libstore_bunzip2.so.$(hurd-version): $(BUNZIP2_OBJS:.o=_pic.o)
# just include all the standard store types in libstore.so itself.
libstore_%.so.$(hurd-version): %_pic.o libstore.so
$(CC) -shared -Wl,-soname=$@ -o $@ \
- $(rpath) $(CFLAGS) $(LDFLAGS) $(libstore_$*.so-LDFLAGS) $^
+ $(lpath) $(CFLAGS) $(LDFLAGS) $(libstore_$*.so-LDFLAGS) $^
# Each libstore_TYPE.a is in fact an object file script so that `-lstore_TYPE'
# just has the same effect as `-u store_TYPE_class'.
Grüße
Thomas
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