@@ -12,3 +12,11 @@ __int128_t __ashlti3(__int128_t a, int b);
__int128_t __ashrti3(__int128_t a, int b);
__int128_t __lshrti3(__int128_t a, int b);
#endif
+
+asmlinkage void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev,
+ struct pt_regs *regs);
+
+asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev,
+ struct pt_regs *regs,
+ int (*fn)(void *),
+ void *fn_arg);
@@ -77,24 +77,22 @@ SYM_CODE_START(handle_syscall)
SYM_CODE_END(handle_syscall)
_ASM_NOKPROBE(handle_syscall)
-SYM_CODE_START(ret_from_fork)
+SYM_CODE_START(ret_from_fork_asm)
UNWIND_HINT_REGS
- bl schedule_tail # a0 = struct task_struct *prev
- move a0, sp
- bl syscall_exit_to_user_mode
+ move a1, sp
+ bl ret_from_fork
RESTORE_STATIC
RESTORE_SOME
RESTORE_SP_AND_RET
-SYM_CODE_END(ret_from_fork)
+SYM_CODE_END(ret_from_fork_asm)
-SYM_CODE_START(ret_from_kernel_thread)
+SYM_CODE_START(ret_from_kernel_thread_asm)
UNWIND_HINT_REGS
- bl schedule_tail # a0 = struct task_struct *prev
- move a0, s1
- jirl ra, s0, 0
- move a0, sp
- bl syscall_exit_to_user_mode
+ move a1, sp
+ move a2, s0
+ move a3, s1
+ bl ret_from_kernel_thread
RESTORE_STATIC
RESTORE_SOME
RESTORE_SP_AND_RET
-SYM_CODE_END(ret_from_kernel_thread)
+SYM_CODE_END(ret_from_kernel_thread_asm)
@@ -14,6 +14,7 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/errno.h>
+#include <linux/entry-common.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
@@ -33,6 +34,7 @@
#include <linux/prctl.h>
#include <linux/nmi.h>
+#include <asm/asm-prototypes.h>
#include <asm/asm.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
@@ -47,6 +49,7 @@
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/reg.h>
+#include <asm/switch_to.h>
#include <asm/unwind.h>
#include <asm/vdso.h>
@@ -63,8 +66,9 @@ EXPORT_SYMBOL(__stack_chk_guard);
unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
EXPORT_SYMBOL(boot_option_idle_override);
-asmlinkage void ret_from_fork(void);
-asmlinkage void ret_from_kernel_thread(void);
+asmlinkage void restore_and_ret(void);
+asmlinkage void ret_from_fork_asm(void);
+asmlinkage void ret_from_kernel_thread_asm(void);
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
{
@@ -138,6 +142,23 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
return 0;
}
+asmlinkage void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev,
+ struct pt_regs *regs)
+{
+ schedule_tail(prev);
+ syscall_exit_to_user_mode(regs);
+}
+
+asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev,
+ struct pt_regs *regs,
+ int (*fn)(void *),
+ void *fn_arg)
+{
+ schedule_tail(prev);
+ fn(fn_arg);
+ syscall_exit_to_user_mode(regs);
+}
+
/*
* Copy architecture-specific thread state
*/
@@ -165,8 +186,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
p->thread.reg03 = childksp;
p->thread.reg23 = (unsigned long)args->fn;
p->thread.reg24 = (unsigned long)args->fn_arg;
- p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
- p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
+ p->thread.reg01 = (unsigned long)ret_from_kernel_thread_asm;
+ p->thread.sched_ra = (unsigned long)ret_from_kernel_thread_asm;
memset(childregs, 0, sizeof(struct pt_regs));
childregs->csr_euen = p->thread.csr_euen;
childregs->csr_crmd = p->thread.csr_crmd;
@@ -182,8 +203,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
childregs->regs[3] = usp;
p->thread.reg03 = (unsigned long) childregs;
- p->thread.reg01 = (unsigned long) ret_from_fork;
- p->thread.sched_ra = (unsigned long) ret_from_fork;
+ p->thread.reg01 = (unsigned long) ret_from_fork_asm;
+ p->thread.sched_ra = (unsigned long) ret_from_fork_asm;
/*
* New tasks lose permission to use the fpu. This accelerates context
LoongArch is the only architecture that calls syscall_exit_to_user_mode() from asm. Move the call into C so that this function can be inlined across all architectures. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- arch/loongarch/include/asm/asm-prototypes.h | 8 +++++++ arch/loongarch/kernel/entry.S | 22 +++++++++---------- arch/loongarch/kernel/process.c | 33 +++++++++++++++++++++++------ 3 files changed, 45 insertions(+), 18 deletions(-)