Add NetBSD support

.github/workflows/build.yaml

@@ -55,6 +55,33 @@ jobs:
             make fmt
             make -C apps/basic fmt
             test -z "$(git status --porcelain)"
+  netbsd-build:
+    name: NetBSD Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Code checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Build on NetBSD
+        uses: vmactions/netbsd-vm@v1
+        with:
+          arch: aarch64
+          usesh: true
+          prepare: |
+            export PKG_PATH="ftp://ftp.NetBSD.org/pub/pkgsrc/packages/$(uname -s)/$(uname -p)/$(uname -r)/All"
+            /usr/sbin/pkg_add -U -v pkgin
+            /usr/pkg/bin/pkgin update
+            /usr/pkg/bin/pkgin install -y clang
+            /sbin/sysctl -w security.pax.mprotect.global=0
+          run: |
+            make clean
+            make -C apps/basic clean
+            make
+            make -C apps/basic
+            make fmt
+            make -C apps/basic fmt
+            test -z "$(git status --porcelain)"
   android-build:
     name: Android Cross Build
     runs-on: ubuntu-latest

Makefile

@@ -31,7 +31,7 @@ OBJS = $(C_SRCS:.c=.o)
 all: $(PROGS)
 
 $(PROGS): $(OBJS)
-	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+	$(CC) $(CFLAGS) -o $@ $(OBJS) $(LDFLAGS)
 
 clean:
 	-@rm -rf $(CLEANFILES)

README.md

@@ -14,7 +14,7 @@ Read [my blog post (ja)](https://retrage.github.io/2024/07/31/svc-hook.html/) fo
 
 ## Target Platform
 
-svc-hook supports ARM64 Linux and FreeBSD.
+svc-hook supports ARM64 Linux, FreeBSD and NetBSD.
 
 ## Build
 

main.c

@@ -18,7 +18,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-#ifdef __FreeBSD__
+#if defined(__FreeBSD__) || defined(__NetBSD__)
 #define PROCFS_MAP "/proc/self/map"
 #else
 #define PROCFS_MAP "/proc/self/maps"
@@ -33,7 +33,7 @@
  * SUPPLEMENTAL: syscall record without syscalls
  */
 #define BM_BACKING_FILE "/tmp/syscall_record"
-#define BM_SIZE (1UL << 9)
+#define BM_SIZE (1UL << 16)  // svc #imm is 16-bit, so 65536 entries
 static char *bm_mem = NULL;
 
 static void bm_init(void) {
@@ -120,7 +120,7 @@ void ____asm_impl(void) {
       "adrp x6, :got:syscall_table \n\t"
       "ldr x6, [x6, #:got_lo12:syscall_table] \n\t"
       "ldr x6, [x6] \n\t"
-      "add x6, x6, xzr, lsl #3 \n\t"
+      "add x6, x6, x8, lsl #3 \n\t"
       "br x6 \n\t");
 
   /*
@@ -138,6 +138,7 @@ void ____asm_impl(void) {
       ".globl asm_syscall_hook \n\t"
       "asm_syscall_hook: \n\t"
 
+#if defined(__linux__)
       "cmp x8, #139 \n\t" /* rt_sigreturn */
       "b.eq do_rt_sigreturn \n\t" /* bypass hook */
       "cmp x8, #220 \n\t" /* clone */
@@ -179,6 +180,7 @@ void ____asm_impl(void) {
       /* Copy x0-x30 to cl_args->stack + cl_args->stack_size */
       SAVE_CONTEXT(x15)
       "b do_syscall_hook \n\t"
+#endif /* defined(__linux__) */
 
       "do_syscall_hook: \n\t"
 
@@ -189,7 +191,9 @@ void ____asm_impl(void) {
 
       /* arguments for syscall_hook */
       "mov x7, x14 \n\t" /* return address */
+#if !defined(__NetBSD__)
       "mov x6, x8 \n\t"  /* syscall NR */
+#endif /* !defined(__NetBSD__) */
 
       "bl syscall_hook \n\t"
 
@@ -508,7 +512,7 @@ static void scan_exec_code(char *code, size_t code_size, int mem_prot,
   close(fd);
 }
 
-#ifdef __FreeBSD__
+#if defined(__FreeBSD__)
 /* entry point for binary scanning on FreeBSD */
 static void scan_code(void) {
   LIST_INIT(&head);
@@ -559,6 +563,57 @@ static void scan_code(void) {
   }
   fclose(fp);
 }
+#elif defined(__NetBSD__)
+/* entry point for binary scanning on NetBSD */
+static void scan_code(void) {
+  LIST_INIT(&head);
+
+  FILE *fp = NULL;
+  /* get memory mapping information from procfs */
+  assert((fp = fopen(PROCFS_MAP, "r")) != NULL);
+  char buf[4096];
+  while (fgets(buf, sizeof(buf), fp) != NULL) {
+    /* we do not touch stack memory */
+    if (strstr(buf, "[stack]") != NULL) {
+      continue;
+    }
+    int mem_prot = 0;
+    int i = 0;
+    char from_addr[65] = {0};
+    char to_addr[65] = {0};
+    char *c = strtok(buf, " ");
+    while (c != NULL) {
+      switch (i) {
+        case 0:
+          strncpy(from_addr, c, sizeof(from_addr) - 1);
+          break;
+        case 1:
+          strncpy(to_addr, c, sizeof(to_addr) - 1);
+          break;
+        case 2:
+          for (size_t j = 0; j < strlen(c); j++) {
+            if (c[j] == 'r') mem_prot |= PROT_READ;
+            if (c[j] == 'w') mem_prot |= PROT_WRITE;
+            if (c[j] == 'x') mem_prot |= PROT_EXEC;
+          }
+          break;
+        case 4:
+          if (strncmp(c, "COW", 3) == 0) {
+            int64_t from = strtol(&from_addr[0], NULL, 16);
+            int64_t to = strtol(&to_addr[0], NULL, 16);
+            if (mem_prot & PROT_EXEC) {
+              scan_exec_code((char *)from, (size_t)to - from, mem_prot, NULL);
+            }
+          }
+          break;
+      }
+      if (i == 4) break;
+      c = strtok(NULL, " ");
+      i++;
+    }
+  }
+  fclose(fp);
+}
 #else
 /* entry point for binary scanning on Linux */
 static void scan_code(void) {