jit object

(cherry picked from commit 9af5422203769f2f939d4a61e7de54b402863bc5)

8 files changed, 267 insertions, 58 deletions

diff --git a/rts/Linker.c b/rts/Linker.c
index e0a3a07dc2..b0ffa46688 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -1630,6 +1630,8 @@ int ocTryLoad (ObjectCode* oc) {
 #   endif
     if (!r) { return r; }
 
+    register_jit_object(oc);
+
     IF_DEBUG(linker, ocDebugBelch(oc, "protecting mappings\n"));
 #if defined(NEED_SYMBOL_EXTRAS)
     ocProtectExtras(oc);
diff --git a/rts/linker/BufferBuilder.c b/rts/linker/BufferBuilder.c
index 2c4f84836e..9f6ff04277 100644
--- a/rts/linker/BufferBuilder.c
+++ b/rts/linker/BufferBuilder.c
@@ -1,15 +1,12 @@
 #include "Rts.h"
-
-struct BufferBuilder {
-    uint8_t *buffer; // start of buffer
-    uint8_t *head;   // next unfilled byte
-    uint8_t *end     // end of buffer
-};
+#include "RtsUtils.h"
+#include "BufferBuilder.h"
+#include <string.h>
 
 struct BufferBuilder buffer_builder_new(size_t initial_sz)
 {
     uint8_t *buffer = stgMallocBytes(initial_sz, "new_buffer_builder");
-    return struct BufferBuilder {
+    return (struct BufferBuilder) {
         .buffer = buffer,
         .head = buffer,
         .end = buffer + initial_sz,
@@ -62,15 +59,3 @@ void buffer_builder_append(struct BufferBuilder *bb, struct BufferBuilder *src)
     buffer_builder_push(bb, bb->buffer, sz);
 }
 
-#define DEFINE_BUILDER(ty) \
-    void buffer_builder_#ty(struct BufferBuilder *bb, ty#_t x) \
-        { return (ty#_t *) buffer_builder_push(bb, &x, sizeof(x)); }
-DEFINE_BUILDER(uint8)
-DEFINE_BUILDER(uint16)
-DEFINE_BUILDER(uint32)
-DEFINE_BUILDER(uint64)
-DEFINE_BUILDER(int8)
-DEFINE_BUILDER(int16)
-DEFINE_BUILDER(int32)
-DEFINE_BUILDER(int64)
-#undef DEFINE_BUILDER
diff --git a/rts/linker/BufferBuilder.h b/rts/linker/BufferBuilder.h
new file mode 100644
index 0000000000..facccb8335
--- /dev/null
+++ b/rts/linker/BufferBuilder.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct BufferBuilder {
+    uint8_t *buffer; // start of buffer
+    uint8_t *head;   // next unfilled byte
+    uint8_t *end;    // end of buffer
+};
+
+struct BufferBuilder buffer_builder_new(size_t initial_sz);
+void buffer_builder_free(struct BufferBuilder *bb);
+size_t buffer_builder_filled_size(struct BufferBuilder *bb);
+size_t buffer_builder_reserved_size(struct BufferBuilder *bb);
+void buffer_builder_realloc(struct BufferBuilder *bb, size_t new_sz);
+uint8_t *buffer_builder_push(struct BufferBuilder *bb, uint8_t *x, size_t sz);
+void buffer_builder_append(struct BufferBuilder *bb, struct BufferBuilder *src);
+
+#define buffer_builder_push_struct(bb, x) \
+    (typeof(x)*) buffer_builder_push(bb, (uint8_t *) &x, sizeof(x))
+
+#define DEFINE_BUILDER(ty) \
+    static inline ty ## _t* buffer_builder_ ## ty(struct BufferBuilder *bb, ty ## _t x) \
+        { return (ty ## _t *) buffer_builder_push(bb, (uint8_t *) &x, sizeof(x)); }
+
+DEFINE_BUILDER(uint8);
+DEFINE_BUILDER(uint16);
+DEFINE_BUILDER(uint32);
+DEFINE_BUILDER(uint64);
+DEFINE_BUILDER(int8);
+DEFINE_BUILDER(int16);
+DEFINE_BUILDER(int32);
+DEFINE_BUILDER(int64);
+
+#undef DEFINE_BUILDER
+
diff --git a/rts/linker/JitObject.c b/rts/linker/JitObject.c
index bd8b432f9e..48652283b7 100644
--- a/rts/linker/JitObject.c
+++ b/rts/linker/JitObject.c
@@ -1,43 +1,62 @@
 #include "BufferBuilder.h"
+#include "JitObject.h"
+#include "LinkerInternals.h"
+#include "RtsUtils.h"
 
-void *build_jit_object_coff(ObjectCode *oc)
+/*
+ * GDB JIT interface
+ */
+
+typedef enum
+{
+  JIT_NOACTION = 0,
+  JIT_REGISTER_FN,
+  JIT_UNREGISTER_FN
+} jit_actions_t;
+
+struct jit_code_entry
 {
-    struct BufferBuilder bb = buffer_builder_new(4096);
-
-    // COFF header
-    buffer_builder_uint16(bb, IMAGE_FILE_MACHINE_AMD64);
-    buffer_builder_uint16(bb, 1); // NumberOfSections
-    buffer_builder_uint32(bb, 0); // TimeDateStamp
-    uint32_t *ptr_to_symbol_table = buffer_builder_uint32(bb, 0); // PointerToSymbolTable
-    buffer_builder_uint32(bb, n_syms); // NumberOfSymbols
-    buffer_builder_uint16(bb, 0); // SizeOfOptionalHeader
-    buffer_builder_uint16(bb, 0); // Characteristics
-
-    // Sections
-    buffer_builder_push(bb, ".text\0\0\0", 8); // Name
-    buffer_builder_uint32(bb, sect_sz);        // VirtualSize
-    buffer_builder_uint32(bb, sect_base);      // VirtualAddress
-    buffer_builder_uint32(bb, 0);              // SizeOfRawData
-    buffer_builder_uint32(bb, 0);              // PointerToRawData
-    buffer_builder_uint32(bb, 0);              // PointerToRelocations
-    buffer_builder_uint32(bb, 0);              // PointerToLinenumbers
-    buffer_builder_uint16(bb, 0);              // NumberOfRelocations
-    buffer_builder_uint16(bb, 0);              // NumberOfLinenumbers
-    buffer_builder_uint32(bb, 0);              // Characteristics
-
-    struct BufferBuilder strings = buffer_builder_new(4096);
-    for (int i=0; i < oc->n_symbols; i++) {
-        Symbol_t *sym = oc->symbols[i];
-        size_t offset = buffer_builder_filled_size(strings);
-        buffer_builder_push(strings, sym->name);
-        buffer_builder_uint32(bb, 0);
-        buffer_builder_uint32(bb, offset); // RawName index
-        buffer_builder_uint32(bb, value);  // Value
-        buffer_builder_uint16(bb, 1);      // SectionNumber
-        buffer_builder_uint8(bb, 0x20);    // StorageClass
-        buffer_builder_uint8(bb, 0);       // NumberOfAuxSymbols
-    }
-
-    buffer_builder_append(bb, strings);
-    return bb->start;
+  struct jit_code_entry *next_entry;
+  struct jit_code_entry *prev_entry;
+  const char *symfile_addr;
+  uint64_t symfile_size;
+};
+
+struct jit_descriptor
+{
+  uint32_t version;
+  /* This type should be jit_actions_t, but we use uint32_t
+     to be explicit about the bitwidth.  */
+  uint32_t action_flag;
+  struct jit_code_entry *relevant_entry;
+  struct jit_code_entry *first_entry;
+};
+
+/* GDB puts a breakpoint in this function.  */
+void __jit_debug_register_code(void);
+void __attribute__((noinline)) __jit_debug_register_code() { };
+
+/* Make sure to specify the version statically, because the
+   debugger may check the version before we can set it.  */
+struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
+
+/*
+ * Registering a JIT object
+ */
+
+void register_jit_object(ObjectCode *oc)
+{
+    struct BufferBuilder buf = build_jit_object(oc);
+
+    struct jit_code_entry *code_entry = stgMallocBytes(sizeof(struct jit_code_entry), "register_jit_object");
+    code_entry->next_entry = __jit_debug_descriptor.first_entry;
+    code_entry->prev_entry = NULL;
+    code_entry->symfile_addr = (const char *) buf.buffer;
+    code_entry->symfile_size = buffer_builder_filled_size(&buf);
+
+    __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
+    __jit_debug_descriptor.first_entry = code_entry;
+    __jit_debug_descriptor.relevant_entry = code_entry;
+    __jit_debug_register_code();
 }
+
diff --git a/rts/linker/JitObject.h b/rts/linker/JitObject.h
new file mode 100644
index 0000000000..1f21ee28c8
--- /dev/null
+++ b/rts/linker/JitObject.h
@@ -0,0 +1,5 @@
+#include "LinkerInternals.h"
+#include "BufferBuilder.h"
+
+void register_jit_object(ObjectCode *oc);
+struct BufferBuilder build_jit_object(ObjectCode *oc);
diff --git a/rts/linker/JitObjectCoff.c b/rts/linker/JitObjectCoff.c
new file mode 100644
index 0000000000..77ce9fecc9
--- /dev/null
+++ b/rts/linker/JitObjectCoff.c
@@ -0,0 +1,47 @@
+#include "BufferBuilder.h"
+#include "JitObject.h"
+#include "LinkerInternals.h"
+#include "RtsUtils.h"
+
+struct BufferBuilder build_jit_object(ObjectCode *oc)
+{
+    struct BufferBuilder bb = buffer_builder_new(4096);
+
+    // COFF header
+    buffer_builder_uint16(&bb, IMAGE_FILE_MACHINE_AMD64);
+    buffer_builder_uint16(&bb, 1); // NumberOfSections
+    buffer_builder_uint32(&bb, 0); // TimeDateStamp
+    uint32_t *ptr_to_symbol_table = buffer_builder_uint32(&bb, 0); // PointerToSymbolTable
+    buffer_builder_uint32(&bb, n_syms); // NumberOfSymbols
+    buffer_builder_uint16(&bb, 0); // SizeOfOptionalHeader
+    buffer_builder_uint16(&bb, 0); // Characteristics
+
+    // Sections
+    buffer_builder_push(&bb, ".text\0\0\0", 8); // Name
+    buffer_builder_uint32(&bb, sect_sz);        // VirtualSize
+    buffer_builder_uint32(&bb, sect_base);      // VirtualAddress
+    buffer_builder_uint32(&bb, 0);              // SizeOfRawData
+    buffer_builder_uint32(&bb, 0);              // PointerToRawData
+    buffer_builder_uint32(&bb, 0);              // PointerToRelocations
+    buffer_builder_uint32(&bb, 0);              // PointerToLinenumbers
+    buffer_builder_uint16(&bb, 0);              // NumberOfRelocations
+    buffer_builder_uint16(&bb, 0);              // NumberOfLinenumbers
+    buffer_builder_uint32(&bb, 0);              // Characteristics
+
+    struct BufferBuilder strings = buffer_builder_new(4096);
+    for (int i=0; i < oc->n_symbols; i++) {
+        Symbol_t *sym = &oc->symbols[i];
+        size_t offset = buffer_builder_filled_size(&strings);
+        buffer_builder_push(&strings, sym->name, strlen(sym->name));
+        buffer_builder_uint32(&bb, 0);
+        buffer_builder_uint32(&bb, offset); // RawName index
+        buffer_builder_uint32(&bb, value);  // Value
+        buffer_builder_uint16(&bb, 1);      // SectionNumber
+        buffer_builder_uint8(&bb, 0x20);    // StorageClass
+        buffer_builder_uint8(&bb, 0);       // NumberOfAuxSymbols
+    }
+
+    buffer_builder_append(&bb, strings);
+    return bb;
+}
+
diff --git a/rts/linker/JitObjectElf.c b/rts/linker/JitObjectElf.c
new file mode 100644
index 0000000000..41653ad45e
--- /dev/null
+++ b/rts/linker/JitObjectElf.c
@@ -0,0 +1,105 @@
+#include "BufferBuilder.h"
+#include "elf_compat.h"
+#include "linker/Elf.h"
+#include "JitObject.h"
+#include "LinkerInternals.h"
+#include "RtsUtils.h"
+
+#include <string.h>
+
+#define TEXT_SECTION_IDX 1
+
+struct BufferBuilder build_jit_object(ObjectCode *oc)
+{
+    struct BufferBuilder bb = buffer_builder_new(4096);
+
+    // ELF header
+    Elf64_Ehdr ehdr = {
+        .e_ident = {
+            ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
+            ELFCLASS64,
+            ELFDATA2LSB,
+            EV_CURRENT,
+        },
+        .e_type = ET_REL,
+        .e_machine = EM_386,
+        .e_version = EV_CURRENT,
+        .e_entry = 0,
+        .e_phoff = 0,
+        .e_shoff = 0, // will be filled in later
+        .e_flags = 0,
+        .e_ehsize = sizeof(Elf64_Ehdr),
+        .e_phentsize = sizeof(Elf64_Phdr),
+        .e_phnum = 0,
+        .e_shentsize = sizeof(Elf64_Shdr),
+        .e_shnum = 2,
+        .e_shstrndx =  0,
+    };
+
+    Elf64_Ehdr *ehdr_ptr = buffer_builder_push_struct(&bb, ehdr);
+
+    // String table
+    struct BufferBuilder strings = buffer_builder_new(4096);
+    buffer_builder_uint8(&strings, 0);
+
+    // Section table
+    struct BufferBuilder shtab = buffer_builder_new(4096);
+    Elf64_Shdr shtab_zero_ent = {
+        .sh_name = 0,
+        .sh_type = SHT_NULL,
+        .sh_flags = 0,
+        .sh_addr = 0,
+        .sh_offset = 0,
+        .sh_size = 0,
+        .sh_link = SHN_UNDEF,
+        .sh_info = 0,
+        .sh_addralign = 0,
+        .sh_entsize = 0,
+    };
+    buffer_builder_push_struct(&shtab, shtab_zero_ent);
+
+    Elf64_Shdr shtab_text_ent = {
+        .sh_name = 1,
+        .sh_type = SHT_NULL,
+        .sh_flags = SHF_ALLOC | SHF_EXECINSTR,
+        .sh_addr = 0,
+        .sh_offset = 0, // will be filled in later
+        .sh_size = 0,
+        .sh_link = SHN_UNDEF,
+        .sh_info = 0,
+        .sh_addralign = 0,
+        .sh_entsize = 0,
+    };
+    buffer_builder_push_struct(&shtab, shtab_zero_ent);
+
+    // Symbol table
+    struct BufferBuilder symtab = buffer_builder_new(4096);
+    Elf64_Sym symtab_zero_ent = {
+        .st_name = 0,
+        .st_value = 0,
+        .st_size = 0,
+        .st_info = 0,
+        .st_other = 0,
+        .st_shndx = SHN_UNDEF,
+    };
+    buffer_builder_push_struct(&symtab, symtab_zero_ent);
+
+    for (int i=0; i < oc->n_symbols; i++) {
+        Symbol_t *sym = &oc->symbols[i];
+        size_t sym_name_offset = buffer_builder_filled_size(&strings);
+        buffer_builder_push(&strings, sym->name, strlen(sym->name)+1);
+
+        Elf64_Sym symtab_ent = {
+            .st_name = sym_name_offset,
+            .st_value = hi,
+            .st_size = 0,
+            .st_info = 0,
+            .st_other = 0,
+            .st_shndx = TEXT_SECTION_IDX,
+        };
+        buffer_builder_push_struct(&symtab, symtab_ent);
+    }
+
+    return bb;
+}
+
diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in
index cc449ee522..e2f0bf11fa 100644
--- a/rts/rts.cabal.in
+++ b/rts/rts.cabal.in
@@ -470,6 +470,13 @@ library
     if arch(ppc) || arch(ppc64) || arch(s390x) || arch(riscv64)
       asm-sources: StgCRunAsm.S
 
+    -- gdb JIT object logic
+    if os(mingw32)
+      c-sources: linker/JitObjectCoff.c
+    else
+      if os(linux) || os(freebsd)
+        c-sources: linker/JitObjectElf.c
+
     c-sources: Adjustor.c
                adjustor/AdjustorPool.c
                ExecPage.c
@@ -548,8 +555,10 @@ library
                hooks/OnExit.c
                hooks/OutOfHeap.c
                hooks/StackOverflow.c
+               linker/BufferBuilder.c
                linker/CacheFlush.c
                linker/Elf.c
+               linker/JitObject.c
                linker/LoadArchive.c
                linker/M32Alloc.c
                linker/MMap.c