Merge pull request #232 from dosemu2/rel2

Rel2

ci_prereq.sh

@@ -1,14 +1,15 @@
 #!/bin/sh
 
+sudo add-apt-repository ppa:stsp-0/nasm-segelf
 sudo apt update -q
 sudo apt install -y \
     bison \
     flex \
     sed \
     bash \
     clang \
-    nasm \
-    lld \
+    nasm-segelf \
+    binutils \
     pkgconf \
     autoconf \
     libelf-dev \

debian/control

@@ -10,8 +10,8 @@ Build-Depends:
     sed,
     bash,
     clang,
-    nasm,
-    lld (>= 13~),
+    nasm-segelf,
+    binutils,
     coreutils,
     libelf-dev,
     autoconf,

fdpp/clang.mak

@@ -2,6 +2,7 @@
 # CLANG.MAK - kernel copiler options for clang
 #
 
+LD ?= ld
 LLD ?= $(shell which ld.lld 2>/dev/null)
 CCACHE ?= $(shell which ccache 2>/dev/null)
 CC = $(CCACHE) clang++
@@ -23,12 +24,11 @@ endif
 CC_FOR_BUILD = $(CCACHE) clang
 CPP = $(CC_FOR_BUILD) -E
 CC_LD = $(CL)
-ifneq ($(LLD),)
+ifeq ($(LD),)
 # ld.lld can cross-compile while gnu ld not
 CROSS_LD ?= $(LLD)
 else
-$(warning lld not installed)
-CROSS_LD ?= ld
+CROSS_LD ?= $(LD)
 endif
 NASM ?= nasm
 PKG_CONFIG ?= pkg-config

fdpp/elf.c

@@ -39,16 +39,99 @@ struct elfstate {
     uint32_t load_offs;
 };
 
-static void elf_dl(char *addr, uint16_t seg)
+static int do_getsym(struct elfstate *state, const char *name, GElf_Sym *r_sym)
 {
-    const int reloc_tab[] = {
-        #include "rel.h"
-    };
-    size_t i;
-#define _countof(array) (sizeof(array) / sizeof(array[0]))
-
-    for (i = 0; i < _countof(reloc_tab); i++)
-        memcpy(&addr[reloc_tab[i]-1], &seg, sizeof(seg));
+    Elf_Data *data;
+    int count, i;
+
+    data = elf_getdata(state->symtab_scn, NULL);
+    count = state->symtab_shdr.sh_size / state->symtab_shdr.sh_entsize;
+
+    for (i = 0; i < count; i++) {
+        GElf_Sym sym;
+        gelf_getsym(data, i, &sym);
+        if (strcmp(elf_strptr(state->elf, state->symtab_shdr.sh_link,
+                sym.st_name), name) == 0) {
+            *r_sym = sym;
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
+static void do_elf_dl(struct elfstate *state, uint16_t seg, Elf_Scn *rel_scn,
+                      GElf_Shdr *rel_shdr)
+{
+    Elf_Data *rel_data;
+    Elf_Data *st_data;
+    int rel_count, st_count, i;
+
+    rel_data = elf_getdata(rel_scn, NULL);
+    rel_count = rel_shdr->sh_size / rel_shdr->sh_entsize;
+    st_data = elf_getdata(state->symtab_scn, NULL);
+    st_count = state->symtab_shdr.sh_size / state->symtab_shdr.sh_entsize;
+
+    for (i = 0; i < rel_count; i++) {
+        uint16_t *val;
+        GElf_Rel rel;
+        GElf_Sym sym;
+        char *name, *name2, *p;
+        int rc;
+
+        gelf_getrel(rel_data, i, &rel);
+        /* look for R_386_SEG16 */
+        if (GELF_R_TYPE(rel.r_info) != R_386_16)
+            continue;
+        if (GELF_R_SYM(rel.r_info) >= st_count) {
+            fprintf(stderr, "bad reloc %lx %i %li off=%lx\n",
+                GELF_R_TYPE(rel.r_info), st_count,
+                GELF_R_SYM(rel.r_info), rel.r_offset);
+            return;
+        }
+        gelf_getsym(st_data, GELF_R_SYM(rel.r_info), &sym);
+#ifndef STT_RELC
+#define STT_RELC 8
+#endif
+        if (GELF_ST_TYPE(sym.st_info) != STT_RELC)
+            continue;
+
+        name = elf_strptr(state->elf, state->symtab_shdr.sh_link, sym.st_name);
+        /* make sure its a SEG16 reloc symbol */
+        if (strncmp(name, ">>:", 3) != 0 || !strstr(name, "04"))
+            continue;
+        p = strstr(name, ":s");
+        if (!p)
+            continue;
+        p = strchr(p + 1, ':');
+        if (!p)
+            continue;
+        name2 = strdup(p + 1);
+        p = strchr(name2, ':');
+        if (p)
+            *p = '\0';
+        rc = do_getsym(state, name2, &sym);
+        free(name2);
+        if (rc)
+            continue;
+
+        /* not relocating against abs symbol */
+        if (sym.st_shndx == SHN_ABS)
+            continue;
+        val = (uint16_t *)(state->addr + state->load_offs + rel.r_offset);
+        *val += seg;
+    }
+}
+
+static void elf_dl(struct elfstate *state, uint16_t seg)
+{
+    Elf_Scn *rel_scn = NULL;
+    while ((rel_scn = elf_nextscn(state->elf, rel_scn)) != NULL) {
+        GElf_Shdr rel_shdr;
+        gelf_getshdr(rel_scn, &rel_shdr);
+        if (rel_shdr.sh_type == SHT_REL)
+            do_elf_dl(state, seg, rel_scn, &rel_shdr);
+    }
 }
 
 void *elf_open(const char *name)
@@ -130,7 +213,7 @@ void elf_reloc(void *arg, uint16_t seg)
 {
     struct elfstate *state = (struct elfstate *)arg;
 
-    elf_dl(state->addr, seg);
+    elf_dl(state, seg);
 }
 
 void elf_close(void *arg)
@@ -144,21 +227,9 @@ void elf_close(void *arg)
 
 static int do_getsymoff(struct elfstate *state, const char *name)
 {
-    Elf_Data *data;
-    int count, i;
-
-    data = elf_getdata(state->symtab_scn, NULL);
-    count = state->symtab_shdr.sh_size / state->symtab_shdr.sh_entsize;
-
-    for (i = 0; i < count; i++) {
-        GElf_Sym sym;
-        gelf_getsym(data, i, &sym);
-        if (strcmp(elf_strptr(state->elf, state->symtab_shdr.sh_link,
-                sym.st_name), name) == 0)
-            return sym.st_value;
-    }
-
-    return -1;
+    GElf_Sym sym;
+    int err = do_getsym(state, name, &sym);
+    return (err ? -1 : sym.st_value);
 }
 
 void *elf_getsym(void *arg, const char *name)

fdpp/kernel.ld

@@ -1,22 +1,29 @@
 /* linker script for fdpp project */
 
-/* these GROUPs play the same role as GROUPS (segments) in OMF */
-/* TINY model, all segments are equal */
-PGROUP = DOS_PSP;
-LGROUP = DOS_PSP;
-DGROUP = DOS_PSP;
-TGROUP = DOS_PSP;
-IGROUP = DOS_PSP;
-
 SECTIONS
   {
+    _LOADADDR = DEFINED(loadaddr) ? loadaddr : .;
+    /* these GROUPs play the same role as GROUPS (segments) in OMF */
+    /* TINY model, all segments are equal */
+    _LGROUP = ABSOLUTE(.);
+    _DGROUP = ABSOLUTE(.);
+    _IGROUP = ABSOLUTE(.);
+    _LGROUP~ = . + _LOADADDR;
+    _DGROUP~ = . + _LOADADDR;
+    _IGROUP~ = . + _LOADADDR;
+
+    . = SIZEOF_HEADERS;
+    . = ALIGN(0x100);
     /* Target PSP section.  */
-    .ptext SIZEOF_HEADERS : {
+    .ptext : {
+		_PGROUP = ABSOLUTE(.);
+		_PGROUP~ = . + _LOADADDR;
 		*(PSP)
+		. = ALIGN(0x100);
     }
 
     /* Target low data+text sections.  */
-    .ltext 0x200 : {
+    .ltext : {
 		*(_IRQTEXT)
 		*(_LOWTEXT)
 		*(_IO_TEXT)

fdpp/makefile

@@ -59,7 +59,16 @@ ALL = $(FDPPLIB) $(FDPPDEVL) $(TARGET).elf $(TARGET).map $(GEN_EXT)
 
 all: $(ALL)
 
-elf.o: rel.h
+want_loadaddr = 0
+ifeq ($(want_loadaddr),1)
+LA = --defsym=loadaddr=0xfa100
+else
+LA = --emit-relocs
+endif
+want_pie = 0
+ifeq ($(want_pie),1)
+PF = -pie
+endif
 
 # New makes have a way to avoid parallel invocation with the use of &:
 # On old make you would write "%.elf %.map :" which is a bit silly
@@ -74,19 +83,9 @@ else
 %.elf %.map : $(DEPS_OF_ELF)
 endif
 	$(CROSS_LD) -melf_i386 -static -Map=$(TARGET).map -o $@ \
-		$(^:%.ld=-T%.ld) --defsym=DOS_PSP=0x60
+		$(LA) $(PF) $(^:%.ld=-T%.ld)
 	chmod -x $@
 
-$(TARGET).elf.tmp: $(srcdir)/kernel.ld $(OBJS) $(PPOBJS) $(DOBJS)
-	$(CROSS_LD) -melf_i386 -static -o $@ \
-		$(^:%.ld=-T%.ld) --defsym=DOS_PSP=0
-	chmod -x $@
-
-rel.h: $(TARGET).elf $(TARGET).elf.tmp
-	cmp -l $^ | grep "140   0" | sed 's/^ *//' | cut -d " " -f 1 | \
-		sed 's/$$/,/' > $@
-
-
 clean:
 	+cd parsers && $(MAKE) srcdir=$(abspath $(srcdir))/parsers clean
 	-$(RM) .tstamp *.map $(TARGET).elf *.inc \
@@ -117,7 +116,7 @@ PLPHDRS = farobj.hpp farptr.hpp dispatch.hpp ctors.hpp
 _PPHDRS = $(PLPHDRS) dosobj.h farhlp.hpp thunks_priv.h smalloc.h \
     farhlp_sta.h
 PPHDRS = $(addprefix $(srcdir)/,$(_PPHDRS))
-GEN_HEADERS = thunk_calls.h thunk_asms.h rel.h
+GEN_HEADERS = thunk_calls.h thunk_asms.h
 GEN_HEADERS_FD = glob_asmdefs.h
 GEN_ASMS = plt.asm cdata.asm
 # dont change file order in GEN_TMP as it matches the gen script

fdpp/thunks.cc

@@ -641,6 +641,7 @@ const char *FdppKernelMapName(void)
 struct krnl_hndl {
     void *elf;
     const void *start;
+    unsigned load_off;
 };
 
 void *FdppKernelLoad(const char *dname, int *len, struct fdpp_bss_list **bss,
@@ -663,7 +664,7 @@ void *FdppKernelLoad(const char *dname, int *len, struct fdpp_bss_list **bss,
         return NULL;
     }
     free(kname);
-    start = elf_getloadaddr(handle);
+    start = elf_getsym(handle, "_start");
     s = elf_getsymoff(handle, "_start");
     if (s == -1)
         goto err_close;
@@ -704,6 +705,7 @@ void *FdppKernelLoad(const char *dname, int *len, struct fdpp_bss_list **bss,
     h = (struct krnl_hndl *)malloc(sizeof(*h));
     h->elf = handle;
     h->start = start;
+    h->load_off = s;
     return h;
 
 err_close:
@@ -716,10 +718,9 @@ const void *FdppKernelReloc(void *handle, uint16_t seg, uint16_t *r_seg)
     int i;
     far_s f;
     struct krnl_hndl *h = (struct krnl_hndl *)handle;
-    unsigned load_off = elf_getloadoff(h->elf);
 
-    assert(!(load_off & 0xf));
-    seg -= load_off >> 4;
+    assert(!(h->load_off & 0xf));
+    seg -= h->load_off >> 4;
     elf_reloc(h->elf, seg);
 
     farhlp_init(&sym_tab);

kernel/glob_asm.h

@@ -1,5 +1,6 @@
 /* grep "ASM " globals.h | grep "extern" | grep ";" | sed 's/extern \(.\+\) ASM \(.\+\);/__ASM(\1, \2) SEMIC/' */
 
+__ASM(UWORD, DOS_PSP) SEMIC
 __ASM(UWORD, NetBios) SEMIC
 __ASM(BYTE *, net_name) SEMIC
 __ASM(BYTE, net_set_count) SEMIC

kernel/kernel.asm

@@ -778,6 +778,8 @@ begin_hma:
 ; to minimize relocations
                 global _DGROUP_
 _DGROUP_        dw DGROUP
+                global _DOS_PSP
+_DOS_PSP        dw PGROUP
 
 %ifdef WATCOM
 ;               32 bit multiplication + division

kernel/main.c

@@ -73,8 +73,6 @@ __segment DosTextSeg = 0;
 
 #endif
 
-UWORD DOS_PSP;
-
 ASMREF(struct lol) LoL = __ASMADDR(DATASTART);
 struct _bprm bprm;
 #define TEXT_SIZE (_InitTextEnd - _HMATextStart)
@@ -91,7 +89,6 @@ VOID ASMCFUNC FreeDOSmain(void)
   DosDataSeg = (__segment) & DATASTART;
   DosTextSeg = (__segment) & prn_dev;
 #endif
-  DOS_PSP = _CS;
   /* back up kernel code to the top of ram */
   lpTop = MK_FP(_SS - (TEXT_SIZE + 15) / 16, 0);
   fmemcpy(lpTop, _HMATextStart, TEXT_SIZE);

kernel/segs.inc

@@ -66,12 +66,14 @@ group   I_GROUP         ID_B ID ID_E IC IDATA IB_B IB IB_E
 
 BITS 16
 ; groups are defined in the linker script kernel.ld
-extern PGROUP
-extern DGROUP
-extern LGROUP
-extern TGROUP
-extern IGROUP
-extern I_GROUP
+extern _PGROUP~
+extern _DGROUP~
+extern _LGROUP~
+extern _IGROUP~
+%define PGROUP seg _PGROUP~
+%define DGROUP seg _DGROUP~
+%define LGROUP seg _LGROUP~
+%define IGROUP seg _IGROUP~
 %define class(x)
 %define stack
 %define INITSTACKSIZE 512