git: ff41239f587f - main - Add AT_USRSTACK{BASE, LIM} AT vectors, and ELF_BSDF_VMNOOVERCOMMIT flag

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=ff41239f587f2c2850c10639bd0ab8b5422b33fa

commit ff41239f587f2c2850c10639bd0ab8b5422b33fa
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2022-09-12 19:32:02 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2022-09-16 20:23:26 +0000

    Add AT_USRSTACK{BASE, LIM} AT vectors, and ELF_BSDF_VMNOOVERCOMMIT flag
    
    Reviewed by:    brooks, imp (previous version)
    Discussed with: markj
    Sponsored by:   The FreeBSD Foundation
    MFC after:      2 weeks
    Differential revision:  https://reviews.freebsd.org/D36540
---
 sys/kern/imgact_elf.c | 14 +++++++++++---
 sys/sys/elf_common.h  |  5 ++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 6c36c880a2c0..1c13a9a7c737 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -1448,7 +1448,8 @@ __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
 	Elf_Auxargs *args = (Elf_Auxargs *)imgp->auxargs;
 	Elf_Auxinfo *argarray, *pos;
 	struct vmspace *vmspace;
-	int error;
+	rlim_t stacksz;
+	int error, bsdflags, oc;
 
 	argarray = pos = malloc(AT_COUNT * sizeof(*pos), M_TEMP,
 	    M_WAITOK | M_ZERO);
@@ -1489,8 +1490,12 @@ __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
 		AUXARGS_ENTRY(pos, AT_HWCAP, *imgp->sysent->sv_hwcap);
 	if (imgp->sysent->sv_hwcap2 != NULL)
 		AUXARGS_ENTRY(pos, AT_HWCAP2, *imgp->sysent->sv_hwcap2);
-	AUXARGS_ENTRY(pos, AT_BSDFLAGS, __elfN(sigfastblock) ?
-	    ELF_BSDF_SIGFASTBLK : 0);
+	bsdflags = 0;
+	bsdflags |= __elfN(sigfastblock) ? ELF_BSDF_SIGFASTBLK : 0;
+	oc = atomic_load_int(&vm_overcommit);
+	bsdflags |= (oc & (SWAP_RESERVE_FORCE_ON | SWAP_RESERVE_RLIMIT_ON)) !=
+	    0 ? ELF_BSDF_VMNOOVERCOMMIT : 0;
+	AUXARGS_ENTRY(pos, AT_BSDFLAGS, bsdflags);
 	AUXARGS_ENTRY(pos, AT_ARGC, imgp->args->argc);
 	AUXARGS_ENTRY_PTR(pos, AT_ARGV, imgp->argv);
 	AUXARGS_ENTRY(pos, AT_ENVC, imgp->args->envc);
@@ -1506,6 +1511,9 @@ __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
 		AUXARGS_ENTRY(pos, AT_KPRELOAD,
 		    vmspace->vm_shp_base + imgp->sysent->sv_vdso_offset);
 	}
+	AUXARGS_ENTRY(pos, AT_USRSTACKBASE, round_page(vmspace->vm_stacktop));
+	stacksz = imgp->proc->p_limit->pl_rlimit[RLIMIT_STACK].rlim_cur;
+	AUXARGS_ENTRY(pos, AT_USRSTACKLIM, stacksz);
 	AUXARGS_ENTRY(pos, AT_NULL, 0);
 
 	free(imgp->auxargs, M_TEMP);
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index 23440f535887..9366593b24bd 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -986,8 +986,10 @@ typedef struct {
 #define	AT_PS_STRINGS	32	/* struct ps_strings */
 #define	AT_FXRNG	33	/* Pointer to root RNG seed version. */
 #define	AT_KPRELOAD	34	/* Base of vdso, preloaded by rtld */
+#define	AT_USRSTACKBASE	35	/* Top of user stack */
+#define	AT_USRSTACKLIM	36	/* Grow limit of user stack */
 
-#define	AT_COUNT	35	/* Count of defined aux entry types. */
+#define	AT_COUNT	37	/* Count of defined aux entry types. */
 
 /*
  * Relocation types.
@@ -1501,5 +1503,6 @@ typedef struct {
 #define	R_X86_64_REX_GOTPCRELX	42
 
 #define	ELF_BSDF_SIGFASTBLK	0x0001	/* Kernel supports fast sigblock */
+#define	ELF_BSDF_VMNOOVERCOMMIT	0x0002
 
 #endif /* !_SYS_ELF_COMMON_H_ */