generate wrappers for syscalls

crt/.gitignore

@@ -0,0 +1,2 @@
+syscalls.c
+

crt/Makefile

@@ -16,6 +16,8 @@
 
 DESTDIR ?= /opt/ps5-payload-sdk
 
+PYTHON ?= python3
+
 CCS := clang-18 clang-17 clang-16 clang-15 clang
 CCS := $(foreach CC,$(CCS),$(if $(shell command -v $(CC) 2> /dev/null),$(CC)))
 CC  := $(firstword $(CCS))
@@ -36,14 +38,19 @@ CFLAGS += -Wall -Werror
 
 all: crt1.o
 
-crt1.o: crt.o klog.o kernel.o rtld.o patch.o mdbg.o env.o
+crt1.o: crt.o klog.o kernel.o rtld.o patch.o mdbg.o env.o syscalls.o
 	$(LD) -r -o $@ $^
 
+syscalls.o: syscalls.c
+
+syscalls.c: ../include/freebsd/sys/syscall.h
+	$(PYTHON) gen_syscall_funcs.py > $@
+
 %.o: %.c
 	$(CC) -c $(CFLAGS) -o $@ $^
 
 clean:
-	rm -f *.o
+	rm -f *.o syscalls.c
 
 install: crt1.o
 	install -d $(DESTDIR)/target/lib

crt/crt.c

@@ -40,30 +40,7 @@ extern int main(int argc, char* argv[], char *envp[]);
 int __klog_init(payload_args_t *args);
 int __kernel_init(payload_args_t* args);
 int __rtld_init(payload_args_t* args);
-
-
-/**
- * The PS5 does not allow syscalls from .text sections that are allocated in
- * shared memory. Instead, we simply assign the approriate registers, and
- * jump directly to a syscall instruction in libkernel (which is not in shared
- * memory).
- **/
-static __attribute__ ((used)) long ptr_syscall = 0;
-asm(".intel_syntax noprefix\n"
-    ".global syscall\n"
-    ".type syscall @function\n"
-    "syscall:\n"
-    "  mov rax, rdi\n"                      // sysno
-    "  mov rdi, rsi\n"                      // arg1
-    "  mov rsi, rdx\n"                      // arg2
-    "  mov rdx, rcx\n"                      // arg3
-    "  mov r10, r8\n"                       // arg4
-    "  mov r8,  r9\n"                       // arg5
-    "  mov r9,  qword ptr [rsp + 8]\n"      // arg6
-    "  jmp qword ptr [rip + ptr_syscall]\n" // syscall
-    "  ret\n"
-    );
-
+int __syscall_init(payload_args_t* args);
 
 static payload_args_t* payload_args = 0;
 
@@ -79,21 +56,14 @@ pre_init(payload_args_t *args) {
   int *__isthreaded;
   int error = 0;
 
-  if(args->sceKernelDlsym(0x1, "getpid", &ptr_syscall)) {
-    if((error=args->sceKernelDlsym(0x2001, "getpid", &ptr_syscall))) {
-      return error;
-    }
-  }
-
-  // jump directly to the syscall instruction
-  // in getpid (provided by libkernel)
-  ptr_syscall += 0xa;
-
   if((error=args->sceKernelDlsym(0x2, "__isthreaded", &__isthreaded))) {
     return error;
   }
   *__isthreaded = 1;
 
+  if((error=__syscall_init(args))) {
+    return error;
+  }
   if((error=__klog_init(args))) {
     return error;
   }

crt/gen_syscall_funcs.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+# Copyright (C) 2024 John Törnblom
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; see the file COPYING. If not see
+# <http://www.gnu.org/licenses/>.
+
+import os
+import string
+
+
+print('''
+static __attribute__ ((used)) long ptr_syscall = 0;
+asm(".intel_syntax noprefix\\n"
+    ".global syscall\\n"
+    ".type syscall @function\\n"
+    "syscall:\\n"
+    "  mov rax, rdi\\n"
+    "  mov rdi, rsi\\n"
+    "  mov rsi, rdx\\n"
+    "  mov rdx, rcx\\n"
+    "  mov r10, r8\\n"
+    "  mov r8,  r9\\n"
+    "  mov r9,  qword ptr [rsp + 8]\\n"
+    "  jmp qword ptr [rip + ptr_syscall]\\n"
+    "  ret\\n"
+    );
+''')
+
+
+syscall_tmpl = string.Template('''
+asm(".intel_syntax noprefix\\n"
+    ".global $sysname\\n"
+    ".type $sysname @function\\n"
+    "$sysname:\\n"
+    "  mov rax, $sysno\\n"
+    "  mov r10, rcx\\n"
+    "  jmp qword ptr [rip + ptr_syscall]\\n"
+    "  ret\\n"
+    );
+''')
+
+header = os.path.dirname(__file__)
+with open(f'{header}/../include/freebsd/sys/syscall.h') as f:
+    s = f.read()
+    for line in s.splitlines():
+        if not line.startswith('#define\tSYS'):
+            continue
+
+        line = line[12:].strip()
+        name, no = line.split()
+        name = name.strip()
+        no = int(no.strip())
+
+        if name.startswith('__acl'):
+            continue
+
+        if name.startswith('__cap'):
+            continue
+
+        if name.startswith('__'):
+            name = name[2:]
+
+        if name in ['syscall', 'pipe', 'MAXSYSCALL']:
+            continue
+
+        if name.startswith('freebsd'):
+            continue
+
+        print(syscall_tmpl.substitute(sysname=name, sysno=no))
+
+
+print('''
+#include "payload.h"
+
+int __syscall_init(payload_args_t* args) {
+  int error;
+  if(args->sceKernelDlsym(0x1, "getpid", &ptr_syscall)) {
+    if((error=args->sceKernelDlsym(0x2001, "getpid", &ptr_syscall))) {
+      return error;
+    }
+  }
+
+  // jump directly to the syscall instruction
+  // in getpid (provided by libkernel)
+  ptr_syscall += 0xa;
+  return 0;
+}
+''')