Rust: implement exceptional kernel termination.

This also adjusts the way backtraces are serialized by kloader.

artiq/runtime.rs/src/kernel.rs

@@ -3,7 +3,6 @@ use board::csr;
 use mailbox;
 
 const KERNELCPU_EXEC_ADDRESS:    usize = 0x42000000;
-const KERNELCPU_PAYLOAD_ADDRESS: usize = 0x42020000;
 const KERNELCPU_LAST_ADDRESS:    usize = (0x4fffffff - 1024*1024);
 const KSUPPORT_HEADER_SIZE:      usize = 0x80;
 

artiq/runtime.rs/src/kernel_proto.rs

@@ -15,8 +15,6 @@ pub struct Exception<'a> {
     pub param:    [u64; 3],
 }
 
-pub use self::c::BacktraceItem;
-
 #[derive(Debug)]
 pub enum Message<'a> {
     LoadRequest(&'a [u8]),
@@ -29,7 +27,7 @@ pub enum Message<'a> {
     RunFinished,
     RunException {
         exception: Exception<'a>,
-        backtrace: &'a [BacktraceItem]
+        backtrace: &'a [usize]
     },
 
     WatchdogSetRequest { ms: u64 },
@@ -315,7 +313,7 @@ mod c {
     pub struct RunException {
         pub ty: Type,
         pub exception: *const Exception,
-        pub backtrace: *const BacktraceItem,
+        pub backtrace: *const usize,
         pub backtrace_size: size_t
     }
 
@@ -417,13 +415,6 @@ mod c {
         pub param:    [u64; 3],
     }
 
-    #[repr(C)]
-    #[derive(Debug)]
-    pub struct BacktraceItem {
-        pub function: usize,
-        pub offset: usize
-    }
-
     pub unsafe fn from_c_str_len<'a>(ptr: *const c_char, len: size_t) -> &'a str {
         str::from_utf8_unchecked(slice::from_raw_parts(ptr as *const u8, len))
     }

artiq/runtime.rs/src/session.rs

@@ -350,12 +350,39 @@ fn process_kern_message(waiter: Waiter,
             }
 
             kern::RunFinished => {
-                try!(kern_acknowledge());
-
                 kernel::stop();
                 session.kernel_state = KernelState::Absent;
 
+                match stream {
+                    None => return Ok(true),
+                    Some(ref mut stream) =>
+                        host_write(stream, host::Reply::KernelFinished)
+                }
+            }
+
+            kern::RunException { exception: ref exn, backtrace } => {
+                kernel::stop();
+                session.kernel_state = KernelState::Absent;
+
+                match stream {
+                    None => {
+                        error!("exception in flash kernel");
+                        error!("{}: {} {:?}", exn.name, exn.message, exn.param);
+                        error!("at {}:{}:{} in {}", exn.file, exn.line, exn.column, exn.function);
                         return Ok(true)
+                    },
+                    Some(ref mut stream) =>
+                        host_write(stream, host::Reply::KernelException {
+                            name: exn.name,
+                            message: exn.message,
+                            param: exn.param,
+                            file: exn.file,
+                            line: exn.line,
+                            column: exn.column,
+                            function: exn.function,
+                            backtrace: backtrace
+                        })
+                }
             }
 
             request => unexpected!("unexpected request {:?} from kernel CPU", request)
@@ -374,9 +401,7 @@ fn host_kernel_worker(waiter: Waiter,
         }
 
         if mailbox::receive() != 0 {
-            if try!(process_kern_message(waiter, Some(stream), &mut session)) {
+            try!(process_kern_message(waiter, Some(stream), &mut session));
-                try!(host_write(stream, host::Reply::KernelFinished))
-            }
         }
 
         if session.kernel_state == KernelState::Running {

artiq/runtime.rs/src/session_proto.rs

@@ -15,46 +15,6 @@ fn write_sync(writer: &mut Write) -> io::Result<()> {
     writer.write_all(&[0x5a; 4])
 }
 
-#[derive(Debug)]
-pub struct Exception {
-    name:     String,
-    message:  String,
-    param:    [u64; 3],
-    file:     String,
-    line:     u32,
-    column:   u32,
-    function: String,
-}
-
-impl Exception {
-    pub fn read_from(reader: &mut Read) -> io::Result<Exception> {
-        Ok(Exception {
-            name:     try!(read_string(reader)),
-            message:  try!(read_string(reader)),
-            param:    [try!(read_u64(reader)),
-                       try!(read_u64(reader)),
-                       try!(read_u64(reader))],
-            file:     try!(read_string(reader)),
-            line:     try!(read_u32(reader)),
-            column:   try!(read_u32(reader)),
-            function: try!(read_string(reader))
-        })
-    }
-
-    pub fn write_to(&self, writer: &mut Write) -> io::Result<()> {
-        try!(write_string(writer, &self.name));
-        try!(write_string(writer, &self.message));
-        try!(write_u64(writer, self.param[0]));
-        try!(write_u64(writer, self.param[1]));
-        try!(write_u64(writer, self.param[2]));
-        try!(write_string(writer, &self.file));
-        try!(write_u32(writer, self.line));
-        try!(write_u32(writer, self.column));
-        try!(write_string(writer, &self.function));
-        Ok(())
-    }
-}
-
 #[derive(Debug)]
 pub enum Request {
     Log,
@@ -67,7 +27,15 @@ pub enum Request {
     RunKernel,
 
     RpcReply { tag: Vec<u8>, data: Vec<u8> },
-    RpcException(Exception),
+    RpcException {
+        name:     String,
+        message:  String,
+        param:    [u64; 3],
+        file:     String,
+        line:     u32,
+        column:   u32,
+        function: String,
+    },
 
     FlashRead   { key: String },
     FlashWrite  { key: String, value: Vec<u8> },
@@ -100,7 +68,17 @@ impl Request {
                 try!(reader.read_exact(&mut data));
                 Request::RpcReply { tag: tag, data: data }
             }
-            8  => Request::RpcException(try!(Exception::read_from(reader))),
+            8  => Request::RpcException {
+                name:     try!(read_string(reader)),
+                message:  try!(read_string(reader)),
+                param:    [try!(read_u64(reader)),
+                           try!(read_u64(reader)),
+                           try!(read_u64(reader))],
+                file:     try!(read_string(reader)),
+                line:     try!(read_u32(reader)),
+                column:   try!(read_u32(reader)),
+                function: try!(read_string(reader))
+            },
             9  => Request::FlashRead {
                 key: try!(read_string(reader))
             },
@@ -130,7 +108,16 @@ pub enum Reply<'a> {
 
     KernelFinished,
     KernelStartupFailed,
-    KernelException(Exception),
+    KernelException {
+        name:      &'a str,
+        message:   &'a str,
+        param:     [u64; 3],
+        file:      &'a str,
+        line:      u32,
+        column:    u32,
+        function:  &'a str,
+        backtrace: &'a [usize]
+    },
 
     RpcRequest { service: u32, data: &'a [u8] },
 
@@ -179,9 +166,23 @@ impl<'a> Reply<'a> {
             Reply::KernelStartupFailed => {
                 try!(write_u8(&mut buf, 8));
             },
-            Reply::KernelException(ref exception) => {
+            Reply::KernelException {
+                name, message, param, file, line, column, function, backtrace
+            } => {
                 try!(write_u8(&mut buf, 9));
-                try!(exception.write_to(writer));
+                try!(write_string(&mut buf, name));
+                try!(write_string(&mut buf, message));
+                try!(write_u64(&mut buf, param[0]));
+                try!(write_u64(&mut buf, param[1]));
+                try!(write_u64(&mut buf, param[2]));
+                try!(write_string(&mut buf, file));
+                try!(write_u32(&mut buf, line));
+                try!(write_u32(&mut buf, column));
+                try!(write_string(&mut buf, function));
+                try!(write_u32(&mut buf, backtrace.len() as u32));
+                for &addr in backtrace {
+                    try!(write_u32(&mut buf, addr as u32))
+                }
             },
 
             Reply::RpcRequest { service, data } => {

artiq/runtime/artiq_personality.c

@@ -233,7 +233,7 @@ struct artiq_raised_exception {
   struct _Unwind_Exception unwind;
   struct artiq_exception artiq;
   int handled;
-  struct artiq_backtrace_item backtrace[1024];
+  uintptr_t backtrace[1024];
   size_t backtrace_size;
 };
 
@@ -303,8 +303,7 @@ static _Unwind_Reason_Code __artiq_uncaught_exception(
   uintptr_t pcOffset = pc - funcStart;
   EH_LOG("===> uncaught (pc=%p+%p)", (void*)funcStart, (void*)pcOffset);
 
-  inflight->backtrace[inflight->backtrace_size].function = funcStart;
+  inflight->backtrace[inflight->backtrace_size] = funcStart + pcOffset;
-  inflight->backtrace[inflight->backtrace_size].offset = pcOffset;
   ++inflight->backtrace_size;
 
   if(actions & _UA_END_OF_STACK) {

artiq/runtime/artiq_personality.h

@@ -17,11 +17,6 @@ struct artiq_exception {
   int64_t param[3];
 };
 
-struct artiq_backtrace_item {
-  intptr_t function;
-  intptr_t offset;
-};
-
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -48,7 +43,7 @@ void __artiq_reraise(void)
 
 /* Called by the runtime */
 void __artiq_terminate(struct artiq_exception *artiq_exn,
-                       struct artiq_backtrace_item *backtrace,
+                       uintptr_t *backtrace,
                        size_t backtrace_size)
         __attribute__((noreturn));
 

artiq/runtime/kloader.c

@@ -58,22 +58,6 @@ void kloader_start_kernel()
     mailbox_acknowledge();
 }
 
-void kloader_filter_backtrace(struct artiq_backtrace_item *backtrace,
-                              size_t *backtrace_size) {
-    struct artiq_backtrace_item *cursor = backtrace;
-
-    // Remove all backtrace items belonging to ksupport and subtract
-    // shared object base from the addresses.
-    for(int i = 0; i < *backtrace_size; i++) {
-        if(backtrace[i].function > KERNELCPU_PAYLOAD_ADDRESS) {
-            backtrace[i].function -= KERNELCPU_PAYLOAD_ADDRESS;
-            *cursor++ = backtrace[i];
-        }
-    }
-
-    *backtrace_size = cursor - backtrace;
-}
-
 static int kloader_start_flash_kernel(char *key)
 {
 #if (defined CSR_SPIFLASH_BASE && defined CONFIG_SPIFLASH_PAGE_SIZE)

artiq/runtime/kloader.h

@@ -1,16 +1,12 @@
 #ifndef __KLOADER_H
 #define __KLOADER_H
 
-#include "artiq_personality.h"
-
 #define KERNELCPU_EXEC_ADDRESS    0x42000000
 #define KERNELCPU_PAYLOAD_ADDRESS 0x42020000
 #define KERNELCPU_LAST_ADDRESS    (0x4fffffff - 1024*1024)
 #define KSUPPORT_HEADER_SIZE      0x80
 
 int kloader_load_library(const void *code);
-void kloader_filter_backtrace(struct artiq_backtrace_item *backtrace,
-                              size_t *backtrace_size);
 
 int kloader_start_startup_kernel(void);
 int kloader_start_idle_kernel(void);

artiq/runtime/ksupport.c

@@ -415,13 +415,26 @@ int main(void)
 
 /* called from __artiq_personality */
 void __artiq_terminate(struct artiq_exception *artiq_exn,
-                       struct artiq_backtrace_item *backtrace,
+                       uintptr_t *backtrace,
                        size_t backtrace_size)
 {
     struct msg_exception msg;
 
     now_save();
 
+    uintptr_t *cursor = backtrace;
+
+    // Remove all backtrace items belonging to ksupport and subtract
+    // shared object base from the addresses.
+    for(int i = 0; i < backtrace_size; i++) {
+        if(backtrace[i] > KERNELCPU_PAYLOAD_ADDRESS) {
+            backtrace[i] -= KERNELCPU_PAYLOAD_ADDRESS;
+            *cursor++ = backtrace[i];
+        }
+    }
+
+    backtrace_size = cursor - backtrace;
+
     msg.type = MESSAGE_TYPE_EXCEPTION;
     msg.exception = artiq_exn;
     msg.backtrace = backtrace;

artiq/runtime/messages.h

@@ -56,7 +56,7 @@ struct msg_now_save {
 struct msg_exception {
     int type;
     struct artiq_exception *exception;
-    struct artiq_backtrace_item *backtrace;
+    uintptr_t *backtrace;
     size_t backtrace_size;
 };
 

artiq/runtime/session.c

@@ -973,13 +973,9 @@ static int process_kmsg(struct msg_base *umsg)
             out_packet_int32(msg->exception->column);
             out_packet_string(msg->exception->function);
 
-            kloader_filter_backtrace(msg->backtrace,
-                                     &msg->backtrace_size);
-
             out_packet_int32(msg->backtrace_size);
             for(int i = 0; i < msg->backtrace_size; i++) {
-                struct artiq_backtrace_item *item = &msg->backtrace[i];
+                out_packet_int32(msg->backtrace[i]);
-                out_packet_int32(item->function + item->offset);
             }
 
             out_packet_finish();