[Valgrind-developers] [valgrind] Darwin stack size

[Paul F. <pa...@so...>]

https://sourceware.org/cgit/valgrind/commit/?id=8338e4a11c695b8b24ccb06bae4ed9d611de4d88

commit 8338e4a11c695b8b24ccb06bae4ed9d611de4d88
Author: Paul Floyd <pj...@wa...>
Date:   Mon Mar 9 08:05:39 2026 +0100

    Darwin stack size
    
    Darwin wasn't using --main-stacksize. Instead the stack was being set
    based on rlimit (in my tests I saw that it could also be set from
    macho, but it appears to specify a size of 0, at least on regtest
    files compiled on macOS 12.
    
    Also unlike other OSes there was no lower/upper limit of 1MB
    and 16MB.
    
    It looks like all four platforms now have duplicated code for setting
    the main client stack size, so I should probably factor it out into
    something like VG_(get_default_stack_size)().
    
    With this change I tried to get the lsframe1 and lsframe2 tests to work.
    With some twiddling of the stack and frame size they seem to work.
    One issue is that Darwin has a function that probes below the stack.
    I think that is related to stack growth. We don't implement a grow down
    stack on Darwin.  The whole stack gets mapped in one go. So this probing
    does not serve much purpose under Valgrind but it does generate a lot of
    memcheck noise.
    
    ~t seems as though the name of this probe function changed with
    macOS 12. Previously it was __chkstk_darwin_probe. With macOS 12
    it is ___chkstk_darwin. So I added a couple of wildcards to the suppressions
    so that they match both versions.

Diff:
---
 coregrind/m_ume/macho.c | 21 +++++++++++++++++----
 darwin.supp             |  6 ++++--
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/coregrind/m_ume/macho.c b/coregrind/m_ume/macho.c
index 22f2d7a0d6..536eef261e 100644
--- a/coregrind/m_ume/macho.c
+++ b/coregrind/m_ume/macho.c
@@ -42,6 +42,7 @@
 #include "pub_core_mallocfree.h"    // VG_(malloc), VG_(free)
 #include "pub_core_syscall.h"       // VG_(strerror)
 #include "pub_core_clientstate.h"
+#include "pub_core_options.h"
 #include "pub_core_ume.h"           // self
 
 #include "priv_ume.h"
@@ -349,10 +350,22 @@ load_genericthread(struct thread_command *threadcmd, int type,
    GrP fixme 64-bit? */
 static vki_size_t default_stack_size(void)
 {
-   struct vki_rlimit lim;
-   int err = VG_(getrlimit)(VKI_RLIMIT_STACK, &lim);
-   if (err) return 8*1024*1024; // 8 MB
-   else return lim.rlim_cur;
+   SizeT m1  = 1024 * 1024;
+   SizeT m16 = 16 * m1;
+   SizeT szB = (SizeT)VG_(client_rlimit_stack).rlim_cur;
+   if (szB < m1) {
+      szB = m1;
+   }
+   if (szB > m16) {
+      szB = m16;
+   }
+   if (VG_(clo_main_stacksize) > 0) {
+      szB = VG_(clo_main_stacksize);
+   }
+   if (szB < m1) {
+      szB = m1;
+   }
+   return szB;
 }
 
 
diff --git a/darwin.supp b/darwin.supp
index b53ea93596..9d6506492c 100644
--- a/darwin.supp
+++ b/darwin.supp
@@ -782,10 +782,12 @@
 
 # I suppose that this is deliberate
 # and that Apple know what they are doing?
+# On macOS 12 at least this seems to have changed name to ___chkstk_darwin
+# this matches both
 {
    macOS1015:__chkstk_darwin_probe
    Memcheck:Addr8
-   fun:__chkstk_darwin_probe
+   fun:__*chkstk_darwin*
 }
 
 {
@@ -815,7 +817,7 @@
 {
    macOS1100:__chkstk_darwin_probe
    Memcheck:Addr1
-   fun:__chkstk_darwin_probe
+   fun:__*chkstk_darwin*
 }
 
 {