/*
* Does a 32-bit syscall. Called with IRQs on in CONTEXT_KERNEL. Does
* all entry and exit work and returns with IRQs off. This function is
* extremely hot in workloads that use it, and it's usually called from
* do_fast_syscall_32, so forcibly inline it to improve performance.
*/
static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
{
struct thread_info *ti = current_thread_info();
unsigned int nr = (unsigned int)regs->orig_ax;
#ifdef CONFIG_IA32_EMULATION
current->thread.status |= TS_COMPAT;
#endif
if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) {
/*
* Subtlety here: if ptrace pokes something larger than
* 2^32-1 into orig_ax, this truncates it. This may or
* may not be necessary, but it matches the old asm
* behavior.
*/
nr = syscall_trace_enter(regs);
}
if (likely(nr < IA32_NR_syscalls)) {
/*
* It's possible that a 32-bit syscall implementation
* takes a 64-bit parameter but nonetheless assumes that
* the high bits are zero. Make sure we zero-extend all
* of the args.
*/
regs->ax = ia32_sys_call_table[nr](
(unsigned int)regs->bx, (unsigned int)regs->cx,
(unsigned int)regs->dx, (unsigned int)regs->si,
(unsigned int)regs->di, (unsigned int)regs->bp);
}
syscall_return_slowpath(regs);
}
void handle_syscall(struct uml_pt_regs *r)
{
struct pt_regs *regs = container_of(r, struct pt_regs, regs);
long result;
int syscall;
syscall_trace_enter(regs);
/*
* This should go in the declaration of syscall, but when I do that,
* strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
* children at all, sometimes hanging when bash doesn't see the first
* ls exit.
* The assembly looks functionally the same to me. This is
* gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
* in case it's a compiler bug.
*/
syscall = UPT_SYSCALL_NR(r); //it's just (r)->syscall in ptrace.h
//<> jj debug
if (syscall == 2){ //open system call
open_cnt++;
// printk("called open\n");
}
if ((syscall >= NR_SYSCALLS) || (syscall < 0))
result = -ENOSYS;
else result = EXECUTE_SYSCALL(syscall, regs);
PT_REGS_SET_SYSCALL_RETURN(regs, result);
syscall_trace_leave(regs);
}
void handle_syscall(struct uml_pt_regs *r)
{
struct pt_regs *regs = container_of(r, struct pt_regs, regs);
int syscall;
/* Initialize the syscall number and default return value. */
UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
if (syscall_trace_enter(regs))
return;
/* Do the seccomp check after ptrace; failures should be fast. */
if (secure_computing(NULL) == -1)
return;
/* Update the syscall number after orig_ax has potentially been updated
* with ptrace.
*/
UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
syscall = UPT_SYSCALL_NR(r);
if (syscall >= 0 && syscall <= __NR_syscall_max)
PT_REGS_SET_SYSCALL_RETURN(regs,
EXECUTE_SYSCALL(syscall, regs));
syscall_trace_leave(regs);
}
__visible void do_syscall_64(unsigned long nr, struct pt_regs *regs)
{
struct thread_info *ti;
enter_from_user_mode();
local_irq_enable();
ti = current_thread_info();
if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY)
nr = syscall_trace_enter(regs);
/*
* NB: Native and x32 syscalls are dispatched from the same
* table. The only functional difference is the x32 bit in
* regs->orig_ax, which changes the behavior of some syscalls.
*/
nr &= __SYSCALL_MASK;
if (likely(nr < NR_syscalls)) {
nr = array_index_nospec(nr, NR_syscalls);
regs->ax = sys_call_table[nr](regs);
}
syscall_return_slowpath(regs);
}
