From: Paul Floyd <pjfloyd@wanadoo.fr>
Date: Tue, 18 Oct 2022 21:38:36 +0000 (+0200)
Subject: Add auxv entry for usrstack on FreeBSD 14, part 1
X-Git-Tag: VALGRIND_3_20_0~8
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=121374b287ce39ef0e42e45dfc27ae0949e6f528;p=thirdparty%2Fvalgrind.git

Add auxv entry for usrstack on FreeBSD 14, part 1

Previously the user stack was obtained using the kern.usrstack
sysctl. This has been moved to auxv in FreeBSD 14. Without
this change all programs linked with libthr fail with a panic
when they fail to get a valid user stack address.

Note also in FreeBSD 14 ASLR has been enabled. This means that
there is now some extra difference between the address layout of
a standalone executable and the same executable under valgrind.

Pre-FreeBSD 14 and under valgrind:
lib rtld is loaded after the executable (though a much smaller gap
inder valgrind)
user stack starts at 0x7ffffffff000

FreeBSD 14
lib rtld is loaded at a much higher address, around 0xeeeecc15000
user stack is at a much lower address, around 0x82073d000

This means that valgrind behaves somewhat as thogh the
kern.elf(64|32).aslr.stack sysctl were set to 0.

Some more work will be needed for the stack size.
There are no plans at the moment to match the FreeBSD 14 memory
layout.
---

diff --git a/coregrind/m_initimg/initimg-freebsd.c b/coregrind/m_initimg/initimg-freebsd.c
index f315a147ff..920ed92911 100644
--- a/coregrind/m_initimg/initimg-freebsd.c
+++ b/coregrind/m_initimg/initimg-freebsd.c
@@ -713,6 +713,15 @@ Addr setup_client_stack( void*  init_sp,
       // case AT_KPRELOAD:
 #endif
 
+#if (FREEBSD_VERS >= FREEBSD_14)
+      case AT_USRSTACKBASE:
+         auxv->u.a_val = VG_(get_usrstack)();
+         break;
+      case AT_USRSTACKLIM:
+         auxv->a_type = AT_IGNORE;
+         break;
+#endif
+
       case AT_PHDR:
          if (info->phdr == 0)
             auxv->a_type = AT_IGNORE;