Add patches to enable runtime

libgo uses backtracking but it leads to page faults. For the time being
it is disabled but it should be revisited in the future.

The second patch decreases the amount of memory maps because it was
exceeding 1G.

Finally, Go uses context switching to manage goroutines. This patch
adds some changes to the way contexts are handled so they can be
compatible with threading in Unikraft.

Signed-off-by: Charalampos Mainas <Charalampos.Mainas@neclab.eu>
Reviewed-by: Felipe Huici <felipe.huici@neclab.eu>

diff --git a/patches/0003-libgo-Disable-backtracing.patch b/patches/0003-libgo-Disable-backtracing.patch
new file mode 100644 (file)
index 0000000..5194363
--- /dev/null
+++ b/patches/0003-libgo-Disable-backtracing.patch
@@ -0,0 +1,28 @@
+From 173b07db3b85d565d650e9368132e311617ea3f1 Mon Sep 17 00:00:00 2001
+From: Costin Lupu <costin.lup@gmail.com>
+Date: Wed, 21 Aug 2019 17:03:25 +0300
+Subject: [PATCH 1/3] libgo: Disable backtracing
+
+Signed-off-by: Charalampos Mainas <charalampos.mainas@neclab.eu>
+---
+ libgo/runtime/go-callers.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/libgo/runtime/go-callers.c b/libgo/runtime/go-callers.c
+index 0c1c60314..a80bc56f5 100644
+--- a/libgo/runtime/go-callers.c
++++ b/libgo/runtime/go-callers.c
+@@ -167,8 +167,8 @@ runtime_callers (int32 skip, Location *locbuf, int32 m, bool keep_thunks)
+   data.max = m;
+   data.keep_thunks = keep_thunks;
+   runtime_xadd (&runtime_in_callers, 1);
+-  backtrace_full (__go_get_backtrace_state (), 0, callback, error_callback,
+-                &data);
++//  backtrace_full (__go_get_backtrace_state (), 0, callback, error_callback,
++//              &data);
+   runtime_xadd (&runtime_in_callers, -1);
+   return data.index;
+ }
+-- 
+2.20.1
+

diff --git a/patches/0004-libgo-Reduce-maximum-memory-size.patch b/patches/0004-libgo-Reduce-maximum-memory-size.patch
new file mode 100644 (file)
index 0000000..7fbf4ea
--- /dev/null
+++ b/patches/0004-libgo-Reduce-maximum-memory-size.patch
@@ -0,0 +1,27 @@
+From caaef739ecf4e87b9994747cbe6c7e627c8678d9 Mon Sep 17 00:00:00 2001
+From: Costin Lupu <costin.lup@gmail.com>
+Date: Wed, 21 Aug 2019 17:03:49 +0300
+Subject: [PATCH 2/3] libgo: Reduce maximum memory size
+
+Signed-off-by: Charalampos Mainas <charalampos.mainas@neclab.eu>
+---
+ libgo/runtime/malloc.goc | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/libgo/runtime/malloc.goc b/libgo/runtime/malloc.goc
+index 232210fc4..211b84748 100644
+--- a/libgo/runtime/malloc.goc
++++ b/libgo/runtime/malloc.goc
+@@ -448,7 +448,8 @@ runtime_mallocinit(void)
+               // but it hardly matters: e0 00 is not valid UTF-8 either.
+               //
+               // If this fails we fall back to the 32 bit memory mechanism
+-              arena_size = MaxMem;
++              //arena_size = MaxMem;
++              arena_size = 104857600;
+               bitmap_size = arena_size / (sizeof(void*)*8/4);
+               spans_size = arena_size / PageSize * sizeof(runtime_mheap.spans[0]);
+               spans_size = ROUND(spans_size, PageSize);
+-- 
+2.20.1
+

diff --git a/patches/0005-libgo-Use-our-context-logic.patch b/patches/0005-libgo-Use-our-context-logic.patch
new file mode 100644 (file)
index 0000000..239058f
--- /dev/null
+++ b/patches/0005-libgo-Use-our-context-logic.patch
@@ -0,0 +1,57 @@
+From 8e22dedf2df725d256235d9bd22fb97f290fd12d Mon Sep 17 00:00:00 2001
+From: Costin Lupu <costin.lup@gmail.com>
+Date: Wed, 21 Aug 2019 17:04:13 +0300
+Subject: [PATCH 3/3] libgo: Use our context logic
+
+Signed-off-by: Charalampos Mainas <charalampos.mainas@neclab.eu>
+---
+ libgo/runtime/proc.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
+index 06a9c2ad6..e8a43272e 100644
+--- a/libgo/runtime/proc.c
++++ b/libgo/runtime/proc.c
+@@ -43,6 +43,10 @@ extern void __splitstack_block_signals_context (void *context[10], int *,
+ 
+ #endif
+ 
++extern size_t get_stack_size();
++extern void makecontext1(ucontext_t *, void *, int);
++extern void *alloc_stack();
++
+ #ifndef PTHREAD_STACK_MIN
+ # define PTHREAD_STACK_MIN 8192
+ #endif
+@@ -831,7 +835,7 @@ makeGContext(G* gp, byte* sp, uintptr spsize) {
+       getcontext(uc);
+       uc->uc_stack.ss_sp = sp;
+       uc->uc_stack.ss_size = (size_t)spsize;
+-      makecontext(uc, kickoff, 0);
++      makecontext1(uc, kickoff, 0);
+ }
+ 
+ // Create a new m.  It will start off with a call to fn, or else the scheduler.
+@@ -1348,7 +1352,8 @@ runtime_malg(bool allocatestack, bool signalstack, byte** ret_stack, uintptr* re
+       }
+       newg = allocg();
+       if(allocatestack) {
+-              stacksize = StackMin;
++              //stacksize = StackMin;
++              stacksize = get_stack_size();
+               if(signalstack) {
+                       stacksize = 32 * 1024; // OS X wants >= 8K, GNU/Linux >= 2K
+ #ifdef SIGSTKSZ
+@@ -1372,7 +1377,8 @@ runtime_malg(bool allocatestack, bool signalstack, byte** ret_stack, uintptr* re
+                 // 32-bit mode, the Go allocation space is all of
+                 // memory anyhow.
+               if(sizeof(void*) == 8) {
+-                      void *p = runtime_SysAlloc(stacksize, &mstats()->other_sys);
++                      //void *p = runtime_SysAlloc(stacksize, &mstats()->other_sys);
++                      void *p = alloc_stack();
+                       if(p == nil)
+                               runtime_throw("runtime: cannot allocate memory for goroutine stack");
+                       *ret_stack = (byte*)p;
+-- 
+2.20.1
+