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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package boot
import (
"fmt"
rpb "gvisor.dev/gvisor/pkg/sentry/arch/registers_go_proto"
)
// reportLimit is the max number of events that should be reported per tracker.
const reportLimit = 100
// argsTracker reports only once for each different combination of arguments.
// It's used for generic syscalls like ioctl to report once per 'cmd'.
type argsTracker struct {
// argsIdx is the syscall arguments to use as unique ID.
argsIdx []int
reported map[string]struct{}
count int
}
func newArgsTracker(argIdx ...int) *argsTracker {
return &argsTracker{argsIdx: argIdx, reported: make(map[string]struct{})}
}
// cmd returns the command based on the syscall argument index.
func (a *argsTracker) key(regs *rpb.AMD64Registers) string {
var rv string
for _, idx := range a.argsIdx {
rv += fmt.Sprintf("%d|", argVal(idx, regs))
}
return rv
}
func argVal(argIdx int, regs *rpb.AMD64Registers) uint32 {
switch argIdx {
case 0:
return uint32(regs.Rdi)
case 1:
return uint32(regs.Rsi)
case 2:
return uint32(regs.Rdx)
case 3:
return uint32(regs.R10)
case 4:
return uint32(regs.R8)
case 5:
return uint32(regs.R9)
}
panic(fmt.Sprintf("invalid syscall argument index %d", argIdx))
}
func (a *argsTracker) shouldReport(regs *rpb.AMD64Registers) bool {
if a.count >= reportLimit {
return false
}
_, ok := a.reported[a.key(regs)]
return !ok
}
func (a *argsTracker) onReported(regs *rpb.AMD64Registers) {
a.count++
a.reported[a.key(regs)] = struct{}{}
}
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