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f37099b699
Currently syscall tracing is a tricky assembly state machine, which can be rather difficult to follow, and even harder to modify. Before we start fiddling with it for pt_regs syscalls, let's convert it to C. This is not intended to have any functional change. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
99 lines
2.3 KiB
C
99 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <linux/context_tracking.h>
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#include <linux/errno.h>
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#include <linux/nospec.h>
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#include <linux/ptrace.h>
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#include <linux/syscalls.h>
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#include <asm/daifflags.h>
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#include <asm/syscall.h>
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#include <asm/thread_info.h>
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long compat_arm_syscall(struct pt_regs *regs);
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asmlinkage long do_ni_syscall(struct pt_regs *regs)
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{
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#ifdef CONFIG_COMPAT
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long ret;
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if (is_compat_task()) {
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ret = compat_arm_syscall(regs);
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if (ret != -ENOSYS)
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return ret;
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}
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#endif
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return sys_ni_syscall();
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}
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static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
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{
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return syscall_fn(regs->regs[0], regs->regs[1], regs->regs[2],
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regs->regs[3], regs->regs[4], regs->regs[5]);
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}
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static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
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unsigned int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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long ret;
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if (scno < sc_nr) {
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syscall_fn_t syscall_fn;
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syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
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ret = __invoke_syscall(regs, syscall_fn);
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} else {
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ret = do_ni_syscall(regs);
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}
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regs->regs[0] = ret;
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}
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static inline bool has_syscall_work(unsigned long flags)
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{
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return unlikely(flags & _TIF_SYSCALL_WORK);
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}
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int syscall_trace_enter(struct pt_regs *regs);
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void syscall_trace_exit(struct pt_regs *regs);
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asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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unsigned long flags = current_thread_info()->flags;
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regs->orig_x0 = regs->regs[0];
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regs->syscallno = scno;
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local_daif_restore(DAIF_PROCCTX);
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user_exit();
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if (has_syscall_work(flags)) {
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/* set default errno for user-issued syscall(-1) */
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if (scno == NO_SYSCALL)
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regs->regs[0] = -ENOSYS;
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scno = syscall_trace_enter(regs);
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if (scno == NO_SYSCALL)
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goto trace_exit;
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}
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invoke_syscall(regs, scno, sc_nr, syscall_table);
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/*
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* The tracing status may have changed under our feet, so we have to
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* check again. However, if we were tracing entry, then we always trace
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* exit regardless, as the old entry assembly did.
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*/
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if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
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local_daif_mask();
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flags = current_thread_info()->flags;
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if (!has_syscall_work(flags))
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return;
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local_daif_restore(DAIF_PROCCTX);
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}
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trace_exit:
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syscall_trace_exit(regs);
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}
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