git: e163ee6ef5b6 - stable/13 - Add kern.elf{32,64}.vdso knobs to enable/disable vdso preloading

The branch stable/13 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=e163ee6ef5b65ec4ae584095ecdff22314613a7f

commit e163ee6ef5b65ec4ae584095ecdff22314613a7f
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2021-11-25 01:31:27 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2022-01-02 16:43:01 +0000

    Add kern.elf{32,64}.vdso knobs to enable/disable vdso preloading
    
    (cherry picked from commit eb029587481e8d6f610eb31d7f50d34b9240f2f2)
---
 sys/kern/imgact_elf.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index c01b9eb7b8a4..721c24af7fe6 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -130,6 +130,15 @@ SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
     nxstack, CTLFLAG_RW, &__elfN(nxstack), 0,
     __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": enable non-executable stack");
 
+#if defined(__amd64__)
+static int __elfN(vdso) = 1;
+SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
+    vdso, CTLFLAG_RWTUN, &__elfN(vdso), 0,
+    __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": enable vdso preloading");
+#else
+static int __elfN(vdso) = 0;
+#endif
+
 #if __ELF_WORD_SIZE == 32 && (defined(__amd64__) || defined(__i386__))
 int i386_read_exec = 0;
 SYSCTL_INT(_kern_elf32, OID_AUTO, read_exec, CTLFLAG_RW, &i386_read_exec, 0,
@@ -1452,7 +1461,7 @@ __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
 	AUXARGS_ENTRY_PTR(pos, AT_PS_STRINGS, imgp->ps_strings);
 	if (imgp->sysent->sv_fxrng_gen_base != 0)
 		AUXARGS_ENTRY(pos, AT_FXRNG, imgp->sysent->sv_fxrng_gen_base);
-	if (imgp->sysent->sv_vdso_base != 0)
+	if (imgp->sysent->sv_vdso_base != 0 && __elfN(vdso) != 0)
 		AUXARGS_ENTRY(pos, AT_KPRELOAD, imgp->sysent->sv_vdso_base);
 	AUXARGS_ENTRY(pos, AT_NULL, 0);