hiwip/gdb-jit-object

(cherry picked from commit 07c9532947a623a065d43ef5f69e530ca762f986)

7 files changed, 186 insertions, 244 deletions

diff --git a/rts/linker/BufferBuilder.c b/rts/linker/BufferBuilder.c
deleted file mode 100644
index 9f6ff04277..0000000000
--- a/rts/linker/BufferBuilder.c
+++ /dev/null
@@ -1,61 +0,0 @@
-#include "Rts.h"
-#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) {
-        .buffer = buffer,
-        .head = buffer,
-        .end = buffer + initial_sz,
-    };
-}
-
-void buffer_builder_free(struct BufferBuilder *bb)
-{
-    stgFree(bb->buffer);
-    bb->buffer = NULL;
-    bb->head = NULL;
-    bb->end = NULL;
-}
-
-size_t buffer_builder_filled_size(struct BufferBuilder *bb)
-{
-    return bb->head - bb->buffer;
-}
-
-size_t buffer_builder_reserved_size(struct BufferBuilder *bb)
-{
-    return bb->end - bb->buffer;
-}
-
-void buffer_builder_realloc(struct BufferBuilder *bb, size_t new_sz)
-{
-    size_t filled_sz = buffer_builder_filled_size(bb);
-    ASSERT(filled_sz <= new_sz);
-    uint8_t *buffer = stgReallocBytes(bb->buffer, new_sz, "new_buffer_builder");
-    bb->buffer = buffer;
-    bb->head = buffer + filled_sz;
-    bb->end = buffer + new_sz;
-}
-
-uint8_t *buffer_builder_push(struct BufferBuilder *bb, uint8_t *x, size_t sz)
-{
-    if (bb->head + sz > bb->end) {
-        buffer_builder_realloc(bb, 2*buffer_builder_reserved_size(bb));
-    }
-
-    memcpy(bb->head, x, sz);
-    uint8_t *ret = bb->head;
-    bb->head += sz;
-    return ret;
-}
-
-void buffer_builder_append(struct BufferBuilder *bb, struct BufferBuilder *src)
-{
-    size_t sz = buffer_builder_filled_size(src);
-    buffer_builder_push(bb, bb->buffer, sz);
-}
-
diff --git a/rts/linker/BufferBuilder.h b/rts/linker/BufferBuilder.h
deleted file mode 100644
index facccb8335..0000000000
--- a/rts/linker/BufferBuilder.h
+++ /dev/null
@@ -1,37 +0,0 @@
-#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 48652283b7..08c1bc987c 100644
--- a/rts/linker/JitObject.c
+++ b/rts/linker/JitObject.c
@@ -1,4 +1,3 @@
-#include "BufferBuilder.h"
 #include "JitObject.h"
 #include "LinkerInternals.h"
 #include "RtsUtils.h"
@@ -46,13 +45,17 @@ struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
 
 void register_jit_object(ObjectCode *oc)
 {
-    struct BufferBuilder buf = build_jit_object(oc);
+    struct JitObject obj = build_jit_object(oc);
+    if (obj.buffer == NULL) {
+        debugBelch("Failed to build JIT object for %s\n", OC_INFORMATIVE_FILENAME(oc));
+        return;
+    }
 
     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);
+    code_entry->symfile_addr = (const char *) obj.buffer;
+    code_entry->symfile_size = obj.size;
 
     __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
     __jit_debug_descriptor.first_entry = code_entry;
diff --git a/rts/linker/JitObject.h b/rts/linker/JitObject.h
index 1f21ee28c8..0b89674026 100644
--- a/rts/linker/JitObject.h
+++ b/rts/linker/JitObject.h
@@ -1,5 +1,9 @@
 #include "LinkerInternals.h"
-#include "BufferBuilder.h"
+
+struct JitObject {
+    uint8_t *buffer;
+    size_t size;
+};
 
 void register_jit_object(ObjectCode *oc);
-struct BufferBuilder build_jit_object(ObjectCode *oc);
+struct JitObject build_jit_object(ObjectCode *oc);
diff --git a/rts/linker/JitObjectCoff.c b/rts/linker/JitObjectCoff.c
deleted file mode 100644
index 77ce9fecc9..0000000000
--- a/rts/linker/JitObjectCoff.c
+++ /dev/null
@@ -1,47 +0,0 @@
-#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
index 41653ad45e..37d042c0b2 100644
--- a/rts/linker/JitObjectElf.c
+++ b/rts/linker/JitObjectElf.c
@@ -1,4 +1,11 @@
-#include "BufferBuilder.h"
+/*
+ * GDB JIT object interface
+ *
+ * This module is responsible for generating and registering dummy interface
+ * files with gdb for reporting symbols loaded by GHC's runtime linker.
+ */
+
+#include "Rts.h"
 #include "elf_compat.h"
 #include "linker/Elf.h"
 #include "JitObject.h"
@@ -7,99 +14,176 @@
 
 #include <string.h>
 
-#define TEXT_SECTION_IDX 1
+#define CC WSTR("clang")
+
+struct temp_file {
+    pathchar *path;
+    FILE *handle;
+};
 
-struct BufferBuilder build_jit_object(ObjectCode *oc)
+static struct temp_file create_temp_file(pathchar *prefix, pathchar *suffix)
 {
-    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,
-    };
+#if defined(mingw32_HOST_OS)
+    // Windows doesn't have a sane temporary file interface that allows setting
+    // of a file suffix. Doing this correctly is quite tiresome so we instead
+    // use this hack since this is just a debugging facility.
+    GUID guid;
+    ZeroMemory(&guid, sizeof (guid));
+    if (CoCreateGuid(&guid) != S_OK) {
+        goto fail;
+    }
+
+    RPC_WSTR guid_str;
+    if (UuidToStringW ((UUID*)&guid, &guid_str) != S_OK) {
+        goto fail;
+    }
 
-    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,
+    size_t path_len = pathlen(prefix) + pathlen(guid_str) + pathlen(suffix) + 1;
+    CHECK(path_len < MAX_PATH);
+    pathchar *path = stgMallocBytes(sizeof(pathchar) * path_len, "create_temp_file");
+    pathcopy(path, prefix);
+    pathcopy(path + pathlen(path), guid_str);
+    pathcopy(path + pathlen(path), suffix);
+
+    FILE *handle = pathopen(path, WSTR("w+"));
+    if (handle == NULL) {
+        debugBelch("build_asm: Failed to create temporary file handle: %s\n", strerror(errno));
+        goto fail;
+    }
+
+    return (struct temp_file) {
+        .path = path,
+        .handle = handle,
     };
-    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,
+#else
+    size_t path_len = strlen(prefix) + 6 + strlen(suffix) + 1;
+    char *path = stgMallocBytes(path_len, "create_temp_file");
+    snprintf(path, path_len, "%sXXXXXX%s", prefix, suffix);
+
+    int fd = mkstemp(path);
+    if (fd == -1) {
+        debugBelch("build_asm: Failed to create temporary file: %s\n", strerror(errno));
+        goto fail;
+    }
+
+    FILE *handle = fdopen(fd, "w+");
+    if (handle == NULL) {
+        debugBelch("build_asm: Failed to create temporary file handle: %s\n", strerror(errno));
+        goto fail;
+    }
+
+    return (struct temp_file) {
+        .path = path,
+        .handle = handle,
     };
-    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,
+#endif
+
+fail:
+    return (struct temp_file) {
+        .path = NULL,
+        .handle = NULL,
     };
-    buffer_builder_push_struct(&symtab, symtab_zero_ent);
+}
 
+/* Returns path to assembler source file */
+static pathchar* build_asm(ObjectCode *oc)
+{
+    struct temp_file f = create_temp_file(WSTR("jit-object"), WSTR(".s"));
+    if (f.path == NULL) {
+        debugBelch("Failed to open JIT object source file: %s\n", strerror(errno));
+        return NULL;
+    }
+
+    //fprintf(f.handle, ".text\n");
     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;
+        const Symbol_t *sym = &oc->symbols[i];
+        if (sym->name) {
+            fprintf(f.handle, ".global %s\n", sym->name);
+#if defined(OBJFORMAT_PEi386)
+            //fprintf(f.handle, ".def %s; .scl 2; .type 32; .endef\n", sym->name);
+#else
+            fprintf(f.handle, ".type %s, %%object\n", sym->name);
+#endif
+            fprintf(f.handle, ".set %s, 0x%" PRIxPTR "\n", sym->name, (uintptr_t) sym->addr);
+        }
+    }
+
+    fclose(f.handle);
+    return f.path;
 }
 
+static ssize_t get_file_size(FILE *f) {
+    long orig_off = ftell(f);
+    if (orig_off == -1) {
+        return -1;
+    }
+    if (fseek(f, 0L, SEEK_END) == -1) {
+        return -1;
+    }
+    long sz = ftell(f);
+    if (sz == -1) {
+        return -1;
+    }
+
+    if (fseek(f, 0L, SEEK_SET) == -1) {
+        return -1;
+    }
+    return sz;
+}
+
+struct JitObject build_jit_object(ObjectCode *oc)
+{
+    pathchar *s_path = build_asm(oc);
+    if (s_path == NULL) {
+        goto fail;
+    }
+
+    struct temp_file f = create_temp_file(WSTR("jit-object"), WSTR(".o"));
+    if (f.path == NULL) {
+        debugBelch("build_jit_object: Failed to create temporary file: %s\n", strerror(errno));
+        goto fail;
+    }
+
+    // Assemble it
+    const int sz = snprintf(NULL, 0, "%" PATH_FMT" -c %" PATH_FMT" -o %" PATH_FMT, CC, s_path, f.path);
+    char *cmdline = malloc(sz+1);
+    snprintf(cmdline, sz+1, "%" PATH_FMT " -c %" PATH_FMT " -o %" PATH_FMT, CC, s_path, f.path);
+    int ret = system(cmdline);
+    free(cmdline);
+    free(s_path);
+    free(f.path);
+    
+    if (ret != 0) {
+        debugBelch("Error assembling JIT object (exit code %d)\n", ret);
+        fclose(f.handle);
+        goto fail;
+    }
+
+    // Read the resulting object
+    ssize_t o_size = get_file_size(f.handle);
+    if (o_size == -1) {
+        debugBelch("Error reading JIT object: %s\n", strerror(errno));
+        goto fail;
+    } else if (o_size == 0) {
+        debugBelch("Assembler produced empty object\n");
+        goto fail;
+    }
+
+    uint8_t *buffer = stgMallocBytes(o_size, "build_jit_object");
+    if (fread(buffer, 1, o_size, f.handle) != (size_t) o_size) {
+        debugBelch("Error reading JIT object: %s\n", strerror(errno));
+        goto fail;
+    }
+    fclose(f.handle);
+
+    return (struct JitObject) {
+        .buffer = buffer,
+        .size = o_size,
+    };
+
+fail:
+    return (struct JitObject) {
+        .buffer = NULL,
+        .size = 0,
+    };
+}
diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in
index e2f0bf11fa..d69ed22c25 100644
--- a/rts/rts.cabal.in
+++ b/rts/rts.cabal.in
@@ -471,11 +471,8 @@ library
       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
+    if os(linux) || os(freebsd)
+      c-sources: linker/JitObjectElf.c
 
     c-sources: Adjustor.c
                adjustor/AdjustorPool.c
@@ -555,7 +552,6 @@ library
                hooks/OnExit.c
                hooks/OutOfHeap.c
                hooks/StackOverflow.c
-               linker/BufferBuilder.c
                linker/CacheFlush.c
                linker/Elf.c
                linker/JitObject.c