git: 5a66ec2748f4 - stable/13 - fork: Allow ABI to specify fork return values for child.
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Date: Fri, 17 Jun 2022 19:37:57 UTC
The branch stable/13 has been updated by dchagin:
URL: https://cgit.FreeBSD.org/src/commit/?id=5a66ec2748f4e81a9c07fe3eaffb8b83578e12f3
commit 5a66ec2748f4e81a9c07fe3eaffb8b83578e12f3
Author: Dmitry Chagin <dchagin@FreeBSD.org>
AuthorDate: 2022-06-17 19:33:28 +0000
Commit: Dmitry Chagin <dchagin@FreeBSD.org>
CommitDate: 2022-06-17 19:33:28 +0000
fork: Allow ABI to specify fork return values for child.
At least Linux x86 ABI's does not use carry bit and expects that the dx register
is preserved. For this add a new sv_set_fork_retval hook and call it from cpu_fork().
Add a short comment about touching dx in x86_set_fork_retval(), for more details
see phab comments from kib@ and imp@.
Reviewed by: kib
Differential revision: https://reviews.freebsd.org/D31472
MFC after: 2 weeks
(cherry picked from commit de8374df28cc23ce0d893fd96d1ad0a861414154)
---
sys/amd64/amd64/elf_machdep.c | 2 ++
sys/amd64/amd64/vm_machdep.c | 15 ++++++++++++---
sys/amd64/cloudabi32/cloudabi32_sysvec.c | 2 ++
sys/amd64/cloudabi64/cloudabi64_sysvec.c | 2 ++
sys/amd64/linux/linux_sysvec.c | 10 ++++++++++
sys/amd64/linux32/linux32_sysvec.c | 10 ++++++++++
sys/compat/ia32/ia32_sysvec.c | 1 +
sys/i386/cloudabi32/cloudabi32_sysvec.c | 2 ++
sys/i386/i386/elf_machdep.c | 1 +
sys/i386/i386/vm_machdep.c | 15 ++++++++++++---
sys/i386/linux/linux_sysvec.c | 11 +++++++++++
sys/kern/imgact_aout.c | 2 ++
sys/kern/init_main.c | 7 +++++++
sys/sys/sysent.h | 2 ++
sys/x86/include/x86_var.h | 1 +
15 files changed, 77 insertions(+), 6 deletions(-)
diff --git a/sys/amd64/amd64/elf_machdep.c b/sys/amd64/amd64/elf_machdep.c
index 6b39fd03f471..f31ec0cca519 100644
--- a/sys/amd64/amd64/elf_machdep.c
+++ b/sys/amd64/amd64/elf_machdep.c
@@ -97,6 +97,7 @@ struct sysentvec elf64_freebsd_sysvec_la48 = {
.sv_onexit = exit_onexit,
.sv_regset_begin = SET_BEGIN(__elfN(regset)),
.sv_regset_end = SET_LIMIT(__elfN(regset)),
+ .sv_set_fork_retval = x86_set_fork_retval,
};
struct sysentvec elf64_freebsd_sysvec_la57 = {
@@ -140,6 +141,7 @@ struct sysentvec elf64_freebsd_sysvec_la57 = {
.sv_onexit = exit_onexit,
.sv_regset_begin = SET_BEGIN(__elfN(regset)),
.sv_regset_end = SET_LIMIT(__elfN(regset)),
+ .sv_set_fork_retval= x86_set_fork_retval,
};
static void
diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index ef4856cbdfd7..e9804c6afb94 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -243,9 +243,8 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
td2->td_frame = (struct trapframe *)td2->td_md.md_stack_base - 1;
bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
- td2->td_frame->tf_rax = 0; /* Child returns zero */
- td2->td_frame->tf_rflags &= ~PSL_C; /* success */
- td2->td_frame->tf_rdx = 1;
+ /* Set child return values. */
+ p2->p_sysent->sv_set_fork_retval(td2);
/*
* If the parent process has the trap bit set (i.e. a debugger
@@ -298,6 +297,16 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
*/
}
+void
+x86_set_fork_retval(struct thread *td)
+{
+ struct trapframe *frame = td->td_frame;
+
+ frame->tf_rax = 0; /* Child returns zero */
+ frame->tf_rflags &= ~PSL_C; /* success */
+ frame->tf_rdx = 1; /* System V emulation */
+}
+
/*
* Intercept the return address from a freshly forked process that has NOT
* been scheduled yet.
diff --git a/sys/amd64/cloudabi32/cloudabi32_sysvec.c b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
index 164f87e90e91..a0b3095c9b7d 100644
--- a/sys/amd64/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <vm/pmap.h>
#include <machine/frame.h>
+#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/vmparam.h>
@@ -224,6 +225,7 @@ static struct sysentvec cloudabi32_elf_sysvec = {
.sv_fetch_syscall_args = cloudabi32_fetch_syscall_args,
.sv_syscallnames = cloudabi32_syscallnames,
.sv_schedtail = cloudabi32_schedtail,
+ .sv_set_fork_retval = x86_set_fork_retval,
};
INIT_SYSENTVEC(elf_sysvec, &cloudabi32_elf_sysvec);
diff --git a/sys/amd64/cloudabi64/cloudabi64_sysvec.c b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
index d3893902b08e..743b216aa05c 100644
--- a/sys/amd64/cloudabi64/cloudabi64_sysvec.c
+++ b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <vm/pmap.h>
#include <machine/frame.h>
+#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/vmparam.h>
@@ -211,6 +212,7 @@ static struct sysentvec cloudabi64_elf_sysvec = {
.sv_fetch_syscall_args = cloudabi64_fetch_syscall_args,
.sv_syscallnames = cloudabi64_syscallnames,
.sv_schedtail = cloudabi64_schedtail,
+ .sv_set_fork_retval = x86_set_fork_retval,
};
INIT_SYSENTVEC(elf_sysvec, &cloudabi64_elf_sysvec);
diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index 08b9a5f1650f..f9ab19a40ef2 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -125,6 +125,7 @@ static void linux_exec_setregs(struct thread *td, struct image_params *imgp,
static void linux_exec_sysvec_init(void *param);
static int linux_on_exec_vmspace(struct proc *p,
struct image_params *imgp);
+static void linux_set_fork_retval(struct thread *td);
static int linux_vsyscall(struct thread *td);
#define LINUX_T_UNKNOWN 255
@@ -268,6 +269,14 @@ linux_set_syscall_retval(struct thread *td, int error)
set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
}
+static void
+linux_set_fork_retval(struct thread *td)
+{
+ struct trapframe *frame = td->td_frame;
+
+ frame->tf_rax = 0;
+}
+
static int
linux_copyout_auxargs(struct image_params *imgp, uintptr_t base)
{
@@ -784,6 +793,7 @@ struct sysentvec elf_linux_sysvec = {
.sv_onexit = linux_on_exit,
.sv_ontdexit = linux_thread_dtor,
.sv_setid_allowed = &linux_setid_allowed_query,
+ .sv_set_fork_retval = linux_set_fork_retval,
};
static int
diff --git a/sys/amd64/linux32/linux32_sysvec.c b/sys/amd64/linux32/linux32_sysvec.c
index 77d6c612c359..42b40ee3094a 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -128,6 +128,7 @@ static bool linux32_trans_osrel(const Elf_Note *note, int32_t *osrel);
static void linux_vdso_install(const void *param);
static void linux_vdso_deinstall(const void *param);
static void linux_vdso_reloc(char *mapping, Elf_Addr offset);
+static void linux32_set_fork_retval(struct thread *td);
static void linux32_set_syscall_retval(struct thread *td, int error);
#define LINUX_T_UNKNOWN 255
@@ -698,6 +699,14 @@ linux32_set_syscall_retval(struct thread *td, int error)
}
}
+static void
+linux32_set_fork_retval(struct thread *td)
+{
+ struct trapframe *frame = td->td_frame;
+
+ frame->tf_rax = 0;
+}
+
/*
* Clear registers on exec
* XXX copied from ia32_signal.c.
@@ -947,6 +956,7 @@ struct sysentvec elf_linux_sysvec = {
.sv_onexit = linux_on_exit,
.sv_ontdexit = linux_thread_dtor,
.sv_setid_allowed = &linux_setid_allowed_query,
+ .sv_set_fork_retval = linux32_set_fork_retval,
};
static int
diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index 7f3ba2da352b..6619301569b1 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -144,6 +144,7 @@ struct sysentvec ia32_freebsd_sysvec = {
.sv_onexit = exit_onexit,
.sv_regset_begin = SET_BEGIN(__elfN(regset)),
.sv_regset_end = SET_LIMIT(__elfN(regset)),
+ .sv_set_fork_retval = x86_set_fork_retval,
};
INIT_SYSENTVEC(elf_ia32_sysvec, &ia32_freebsd_sysvec);
diff --git a/sys/i386/cloudabi32/cloudabi32_sysvec.c b/sys/i386/cloudabi32/cloudabi32_sysvec.c
index 4f12d2b6cbce..f81f334ce75f 100644
--- a/sys/i386/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/i386/cloudabi32/cloudabi32_sysvec.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <vm/pmap.h>
#include <machine/frame.h>
+#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/vmparam.h>
@@ -194,6 +195,7 @@ static struct sysentvec cloudabi32_elf_sysvec = {
.sv_fetch_syscall_args = cloudabi32_fetch_syscall_args,
.sv_syscallnames = cloudabi32_syscallnames,
.sv_schedtail = cloudabi32_schedtail,
+ .sv_set_fork_retval = x86_set_fork_retval,
};
INIT_SYSENTVEC(elf_sysvec, &cloudabi32_elf_sysvec);
diff --git a/sys/i386/i386/elf_machdep.c b/sys/i386/i386/elf_machdep.c
index 4e9fe52d4e7e..874b4249024e 100644
--- a/sys/i386/i386/elf_machdep.c
+++ b/sys/i386/i386/elf_machdep.c
@@ -92,6 +92,7 @@ struct sysentvec elf32_freebsd_sysvec = {
.sv_onexit = exit_onexit,
.sv_regset_begin = SET_BEGIN(__elfN(regset)),
.sv_regset_end = SET_LIMIT(__elfN(regset)),
+ .sv_set_fork_retval = x86_set_fork_retval,
};
INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index 5626f9594ecf..ba1bc996bda4 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -258,9 +258,8 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
VM86_STACK_SPACE) - 1;
bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
- td2->td_frame->tf_eax = 0; /* Child returns zero */
- td2->td_frame->tf_eflags &= ~PSL_C; /* success */
- td2->td_frame->tf_edx = 1;
+ /* Set child return values. */
+ p2->p_sysent->sv_set_fork_retval(td2);
/*
* If the parent process has the trap bit set (i.e. a debugger
@@ -302,6 +301,16 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
*/
}
+void
+x86_set_fork_retval(struct thread *td)
+{
+ struct trapframe * frame = td->td_frame;
+
+ frame->tf_eax = 0; /* Child returns zero */
+ frame->tf_eflags &= ~PSL_C; /* success */
+ frame->tf_edx = 1; /* System V emulation */
+}
+
/*
* Intercept the return address from a freshly forked process that has NOT
* been scheduled yet.
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index c3974e71b8e8..6805a29204c5 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -108,6 +108,7 @@ static int linux_on_exec_vmspace(struct proc *p,
struct image_params *imgp);
static int linux_copyout_strings(struct image_params *imgp,
uintptr_t *stack_base);
+static void linux_set_fork_retval(struct thread *td);
static bool linux_trans_osrel(const Elf_Note *note, int32_t *osrel);
static void linux_vdso_install(const void *param);
static void linux_vdso_deinstall(const void *param);
@@ -798,6 +799,14 @@ linux_set_syscall_retval(struct thread *td, int error)
}
}
+static void
+linux_set_fork_retval(struct thread *td)
+{
+ struct trapframe *frame = td->td_frame;
+
+ frame->tf_eax = 0;
+}
+
/*
* exec_setregs may initialize some registers differently than Linux
* does, thus potentially confusing Linux binaries. If necessary, we
@@ -852,6 +861,7 @@ struct sysentvec linux_sysvec = {
.sv_onexit = linux_on_exit,
.sv_ontdexit = linux_thread_dtor,
.sv_setid_allowed = &linux_setid_allowed_query,
+ .sv_set_fork_retval = linux_set_fork_retval,
};
INIT_SYSENTVEC(aout_sysvec, &linux_sysvec);
@@ -895,6 +905,7 @@ struct sysentvec elf_linux_sysvec = {
.sv_onexit = linux_on_exit,
.sv_ontdexit = linux_thread_dtor,
.sv_setid_allowed = &linux_setid_allowed_query,
+ .sv_set_fork_retval = linux_set_fork_retval,
};
static int
diff --git a/sys/kern/imgact_aout.c b/sys/kern/imgact_aout.c
index b7ff48dd8cdc..1818e5665caf 100644
--- a/sys/kern/imgact_aout.c
+++ b/sys/kern/imgact_aout.c
@@ -104,6 +104,7 @@ struct sysentvec aout_sysvec = {
.sv_trap = NULL,
.sv_onexec_old = exec_onexec_old,
.sv_onexit = exit_onexit,
+ .sv_set_fork_retval = x86_set_fork_retval,
};
#elif defined(__amd64__)
@@ -151,6 +152,7 @@ struct sysentvec aout_sysvec = {
.sv_syscallnames = freebsd32_syscallnames,
.sv_onexec_old = exec_onexec_old,
.sv_onexit = exit_onexit,
+ .sv_set_fork_retval = x86_set_fork_retval,
};
static void
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 8226d8ffd434..aaa4f65f0000 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -402,6 +402,12 @@ null_set_syscall_retval(struct thread *td __unused, int error __unused)
panic("null_set_syscall_retval");
}
+static void
+null_set_fork_retval(struct thread *td __unused)
+{
+
+}
+
struct sysentvec null_sysvec = {
.sv_size = 0,
.sv_table = NULL,
@@ -433,6 +439,7 @@ struct sysentvec null_sysvec = {
.sv_trap = NULL,
.sv_regset_begin = NULL,
.sv_regset_end = NULL,
+ .sv_set_fork_retval = null_set_fork_retval,
};
/*
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index 7696879112e5..045fa382ca25 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -160,6 +160,8 @@ struct sysentvec {
struct image_params *imgp);
struct regset **sv_regset_begin;
struct regset **sv_regset_end;
+ void (*sv_set_fork_retval)(struct thread *);
+ /* Only used on x86 */
};
#define SV_ILP32 0x000100 /* 32-bit executable. */
diff --git a/sys/x86/include/x86_var.h b/sys/x86/include/x86_var.h
index 85c2eec5d005..e4c3fe797a00 100644
--- a/sys/x86/include/x86_var.h
+++ b/sys/x86/include/x86_var.h
@@ -152,6 +152,7 @@ int user_dbreg_trap(register_t dr6);
int cpu_minidumpsys(struct dumperinfo *, const struct minidumpstate *);
struct pcb *get_pcb_td(struct thread *td);
uint64_t rdtsc_ordered(void);
+void x86_set_fork_retval(struct thread *td);
/*
* MSR ops for x86_msr_op()