[PATCH 0/3] um: Remove userspace_pid[]

[PATCH 0/3] um: Remove userspace_pid[]

[Tiwei Bie]

From: Tiwei Bie <tiwei.btw@antgroup.com>

Tiwei Bie (3):
  um: Use err consistently in userspace()
  um: Remove the pid parameter of handle_trap()
  um: Stop tracking stub's PID via userspace_pid[]

 arch/um/include/asm/mmu_context.h   |  9 +-------
 arch/um/include/shared/skas/mm_id.h |  2 --
 arch/um/kernel/exec.c               |  2 --
 arch/um/os-Linux/skas/process.c     | 33 ++++++++++++-----------------
 4 files changed, 15 insertions(+), 31 deletions(-)

-- 
2.34.1

[PATCH 1/3] um: Use err consistently in userspace()

[Tiwei Bie]

From: Tiwei Bie <tiwei.btw@antgroup.com>

Avoid declaring a new variable 'ret' inside the 'if (using_seccomp)'
block, as the existing 'err' variable declared at the top of the
function already serves the same purpose.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/os-Linux/skas/process.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index e42ffac23e3c..2de7fbc6eb23 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -592,12 +592,11 @@ void userspace(struct uml_pt_regs *regs)
 		if (using_seccomp) {
 			struct mm_id *mm_id = current_mm_id();
 			struct stub_data *proc_data = (void *) mm_id->stack;
-			int ret;
 
-			ret = set_stub_state(regs, proc_data, singlestepping());
-			if (ret) {
+			err = set_stub_state(regs, proc_data, singlestepping());
+			if (err) {
 				printk(UM_KERN_ERR "%s - failed to set regs: %d",
-				       __func__, ret);
+				       __func__, err);
 				fatal_sigsegv();
 			}
 
@@ -623,10 +622,10 @@ void userspace(struct uml_pt_regs *regs)
 			mm_id->syscall_data_len = 0;
 			mm_id->syscall_fd_num = 0;
 
-			ret = get_stub_state(regs, proc_data, NULL);
-			if (ret) {
+			err = get_stub_state(regs, proc_data, NULL);
+			if (err) {
 				printk(UM_KERN_ERR "%s - failed to get regs: %d",
-				       __func__, ret);
+				       __func__, err);
 				fatal_sigsegv();
 			}
 
-- 
2.34.1

[PATCH 2/3] um: Remove the pid parameter of handle_trap()

[Tiwei Bie]

From: Tiwei Bie <tiwei.btw@antgroup.com>

It's no longer used. Remove it.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/os-Linux/skas/process.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 2de7fbc6eb23..e90a0658bba8 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -267,7 +267,7 @@ static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 	memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
 }
 
-static void handle_trap(int pid, struct uml_pt_regs *regs)
+static void handle_trap(struct uml_pt_regs *regs)
 {
 	if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
 		fatal_sigsegv();
@@ -755,7 +755,7 @@ void userspace(struct uml_pt_regs *regs)
 				handle_syscall(regs);
 				break;
 			case SIGTRAP + 0x80:
-				handle_trap(pid, regs);
+				handle_trap(regs);
 				break;
 			case SIGTRAP:
 				relay_signal(SIGTRAP, (struct siginfo *)si, regs, NULL);
-- 
2.34.1

[PATCH 3/3] um: Stop tracking stub's PID via userspace_pid[]

[Tiwei Bie]

From: Tiwei Bie <tiwei.btw@antgroup.com>

The PID of the stub process can be obtained from current_mm_id().
There is no need to track it via userspace_pid[]. Stop doing that
to simplify the code.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/include/asm/mmu_context.h   |  9 +--------
 arch/um/include/shared/skas/mm_id.h |  2 --
 arch/um/kernel/exec.c               |  2 --
 arch/um/os-Linux/skas/process.c     | 16 ++++++----------
 4 files changed, 7 insertions(+), 22 deletions(-)

diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 23dcc914d44e..0bbb24868557 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -16,11 +16,6 @@
 #define activate_mm activate_mm
 static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
 {
-	/*
-	 * This is called by fs/exec.c and sys_unshare()
-	 * when the new ->mm is used for the first time.
-	 */
-	__switch_mm(&new->context.id);
 }
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 
@@ -28,11 +23,9 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 {
 	unsigned cpu = smp_processor_id();
 
-	if(prev != next){
+	if (prev != next) {
 		cpumask_clear_cpu(cpu, mm_cpumask(prev));
 		cpumask_set_cpu(cpu, mm_cpumask(next));
-		if(next != &init_mm)
-			__switch_mm(&next->context.id);
 	}
 }
 
diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
index 89df9a55fbea..4f977ef5dda5 100644
--- a/arch/um/include/shared/skas/mm_id.h
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -19,8 +19,6 @@ struct mm_id {
 	int syscall_fd_map[STUB_MAX_FDS];
 };
 
-void __switch_mm(struct mm_id *mm_idp);
-
 void notify_mm_kill(int pid);
 
 #endif
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index cb8b5cd9285c..13812fa97eee 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -26,8 +26,6 @@ void flush_thread(void)
 
 	get_safe_registers(current_pt_regs()->regs.gp,
 			   current_pt_regs()->regs.fp);
-
-	__switch_mm(&current->mm->context.id);
 }
 
 void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index e90a0658bba8..702ff2aeb32a 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -434,7 +434,6 @@ static int __init init_stub_exe_fd(void)
 __initcall(init_stub_exe_fd);
 
 int using_seccomp;
-int userspace_pid[NR_CPUS];
 
 /**
  * start_userspace() - prepare a new userspace process
@@ -553,7 +552,7 @@ extern unsigned long tt_extra_sched_jiffies;
 
 void userspace(struct uml_pt_regs *regs)
 {
-	int err, status, op, pid = userspace_pid[0];
+	int err, status, op;
 	siginfo_t si_ptrace;
 	siginfo_t *si;
 	int sig;
@@ -562,6 +561,8 @@ void userspace(struct uml_pt_regs *regs)
 	interrupt_end();
 
 	while (1) {
+		struct mm_id *mm_id = current_mm_id();
+
 		/*
 		 * When we are in time-travel mode, userspace can theoretically
 		 * do a *lot* of work without being scheduled. The problem with
@@ -590,7 +591,6 @@ void userspace(struct uml_pt_regs *regs)
 		current_mm_sync();
 
 		if (using_seccomp) {
-			struct mm_id *mm_id = current_mm_id();
 			struct stub_data *proc_data = (void *) mm_id->stack;
 
 			err = set_stub_state(regs, proc_data, singlestepping());
@@ -644,8 +644,10 @@ void userspace(struct uml_pt_regs *regs)
 				GET_FAULTINFO_FROM_MC(regs->faultinfo, mcontext);
 			}
 		} else {
+			int pid = mm_id->pid;
+
 			/* Flush out any pending syscalls */
-			err = syscall_stub_flush(current_mm_id());
+			err = syscall_stub_flush(mm_id);
 			if (err) {
 				if (err == -ENOMEM)
 					report_enomem();
@@ -776,7 +778,6 @@ void userspace(struct uml_pt_regs *regs)
 				       __func__, sig);
 				fatal_sigsegv();
 			}
-			pid = userspace_pid[0];
 			interrupt_end();
 
 			/* Avoid -ERESTARTSYS handling in host */
@@ -901,8 +902,3 @@ void reboot_skas(void)
 	block_signals_trace();
 	UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT);
 }
-
-void __switch_mm(struct mm_id *mm_idp)
-{
-	userspace_pid[0] = mm_idp->pid;
-}
-- 
2.34.1