path: root/packages/uclibc/uclibc-0.9.27/thumb-interwork-asm.patch

--- uClibc-0.9.27/ldso/include/dl-elf.h	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/ldso/include/dl-elf.h	2005-08-12 18:24:43.000000000 -0700
@@ -112,6 +112,13 @@
 # define ELF_RTYPE_CLASS_COPY	(0x2)
 #endif
 #define ELF_RTYPE_CLASS_PLT	(0x1)
+/* The type class can be qualified by a list (mask) of the acceptable
+ * STT_ symbol types, if not given the default is everything numerically
+ * <= STT_FUNC (from the original code...)
+ */
+#define ELF_RTYPE_CLASS_OF(type) ((1<<2) << (type))
+#define ELF_RTYPE_CLASS_ALL      (0xffff << 2)
+#define ELF_RTYPE_CLASS_DEFAULT  (((ELF_RTYPE_CLASS_OF(STT_FUNC) << 1) - 1)&ELF_RTYPE_CLASS_ALL)
 
 
 /* Convert between the Linux flags for page protections and the
--- uClibc-0.9.27/ldso/ldso/arm/resolve.S	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/ldso/ldso/arm/resolve.S	2005-08-13 15:08:27.523344709 -0700
@@ -1,43 +1,117 @@
 /*
- * This function is _not_ called directly.  It is jumped to (so no return
- * address is on the stack) when attempting to use a symbol that has not yet
- * been resolved.  The first time a jump symbol (such as a function call inside
- * a shared library) is used (before it gets resolved) it will jump here to
- * _dl_linux_resolve.  When we get called the stack looks like this:
- *	reloc_entry
- *	tpnt
- *
- * This function saves all the registers, puts a copy of reloc_entry and tpnt
- * on the stack (as function arguments) then make the function call
- * _dl_linux_resolver(tpnt, reloc_entry).  _dl_linux_resolver() figures out
- * where the jump symbol is _really_ supposed to have jumped to and returns
- * that to us.  Once we have that, we overwrite tpnt with this fixed up
- * address. We then clean up after ourselves, put all the registers back how we
- * found them, then we jump to the fixed up address, which is where the jump
- * symbol that got us here really wanted to jump to in the first place.
- *  -Erik Andersen
+ * On ARM the PLT contains the following three instructions (for ARM calls):
+ *
+ *	add   ip, pc, #0xNN00000
+ *	add   ip, ip, #0xNN000
+ *	ldr   pc, [ip, #0xNNN]!
+ *
+ * So that, effectively, causes the following to happen:
+ *
+ *	ip := pc+0x0NNNNNNN
+ *	pc := *ip
+ *
+ * For thumb the above fragment is preceded by "bx pc, nop" to switch to ARM
+ * mode and the thumb 'bl' must go to PLT-4 - the PLT entry is expanded by
+ * four bytes to accomodate the trampoline code.
+ *
+ * 0x0NNNNNNN is the offset of the GOT entry for this function relative to
+ * the PLT entry for this function (where the code is).  So the code in the
+ * PLT causes a branch to whatever is in the GOT, leaving the actual address
+ * of the GOT entry in ip.  (Note that the GOT must follow the PLT - the
+ * added value is 28 bit unsigned).
+ *
+ * ip is a pointer to the GOT entry for this function, the first time round
+ * *ip points to this code:
+ *
+ *	str   lr, [sp, #-4]!	@ save lr
+ *	ldr   lr, [pc, #4]	@ lr := *dat (&GOT_TABLE[0]-.)
+ *	add   lr, pc, lr	@ lr += &dat (so lr == &GOT_TABLE[0])
+ *	ldr   pc, [lr, #8]!	@ pc := GOT_TABLE[2]
+ *dat:	.long &GOT_TABLE[0] - .
+ *
+ * (this code is actually held in the first entry of the PLT).  The code
+ * preserves lr then uses it as a scratch register (this preserves the ip
+ * value calculated above).  GOT_TABLE[2] is initialized by INIT_GOT in
+ * dl-sysdep.h to point to _dl_linux_resolve - this function.  The first
+ * three entries in the GOT are reserved, then they are followed by the
+ * entries for the PLT entries, in order.
+ *
+ * The linker initialises the following (non-reserved) GOT entries to
+ * the offset of the PLT with an associated relocation so that on load
+ * the entry is relocated to point to the PLT - the above code.
+ *
+ * The net effect of all this is that on the first call to an external (as
+ * yet unresolved) function all seven of the above instructions are
+ * executed in sequence and the program ends up executing _dl_linux_resolve
+ * with the following important values in registers:
+ *
+ *	ip - a pointer to the GOT entry for the as yet unresolved function
+ *	lr - &GOT_TABLE[2]
+ *
+ * GOT_TABLE[2] has already been initialised to _dl_linux_resolve, and
+ * GOT_TABLE[1] is a pointer to the (elf_resolve*) from INIT_GOT.
+ * _dl_linux_resolve unfrobnicates the ip and lr values to obtain arguments
+ * for a call to _dl_linux_resolver (not the additional 'r' on the end) -
+ * this is in elfinterp.c in this directory.  The call takes arguments:
+ *
+ *	_dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
+ *
+ * And returns the address of the function, it also overwrites the GOT
+ * table entry so that the next time round only the first code fragment will
+ * be executed - it will call the function directly.
+ *
+ * [[Of course, this simply doesn't work on ARM 4T with a thumb target - because
+ * 4T did not do the thumb/arm change on ldr pc!  It can be made to work by
+ * changing _dl_linux_resolver to return __%s_from_arm for an STT_TFUNC, but
+ * this hasn't been done, and there is no guarantee that the linker generated
+ * that glue anyway.]]
+ *
+ * _dl_linux_resolve gets the arguments to call the resolver as follows:
+ *
+ *	tpnt		GOT_TABLE[1], [lr-4]
+ *	reloc-entry	&GOT-&GOT_TABLE[3], (ip - lr - 4)/4
+ *
+ * (I.e. 'GOT' means the table entry for this function, the thing for which
+ * ip holds the address.)  The reloc-entry is passed as an index, since
+ * since the GOT table has 4 byte entries the code needs to divide this by 4
+ * to get the actual index.
+ *
+ * John Bowler, August 13, 2005 - determined by experiment and examination
+ * of generated ARM code (there was no documentation...)
+ *
+ * This code is all ARM code - not thumb - _dl_linux_resolver may, itself,
+ * be thumb, in which case the linker will insert the appropriate glue.  A
+ * call from thumb to the PLT hits the trampoline code described above.
+ * This code (now) builds a proper stack frame.
+ *
+ * The code does *not* set sb (r9,v6) - to do that the basic PLT instructions
+ * would need to save sb and load the new value and that would require
+ * support in the linker since it generates those instructions.  (Also note
+ * that linux/uclibc seems to be using r10 - sl - as a PIC base register - see
+ * dl-startup.c).
  */
 
-#define sl r10
-#define fp r11
-#define ip r12
-
 .text
 .globl _dl_linux_resolve
 .type _dl_linux_resolve,%function
 .align 4;
 
 _dl_linux_resolve:
-	stmdb sp!, {r0, r1, r2, r3, sl, fp}
-	sub r1, ip, lr
-	sub r1, r1, #4
-	add r1, r1, r1
-	ldr r0, [lr, #-4]
-	mov r3,r0
+	@ _dl_linux_resolver is a standard subroutine call, therefore it
+	@ preserves everything except r0-r3 (a1-a4), ip and lr.  This
+	@ function must branch to the real function, and that expects
+	@ r0-r3 and lr to be as they were before the whole PLT stuff -
+	@ ip can be trashed.
+	stmdb sp!, {r0-r3}
+	ldr r0, [lr, #-4]	@ r0 := [lr-4] (GOT_TABLE[1])
+	sub r1, lr, ip		@ r1 := (lr-ip) (a multple of 4)
+	mvn r1, r1, ASR #2	@ r1 := ~((lr-ip)>>2), since -x = (1+~x)
+				@ ~x = -x-1, therefore ~(r1>>2) = (-((lr-ip)>>2)-1)
+				@ = - ((lr-ip)/4) - 1 = (ip - lr - 4)/4, as required
 
 	bl _dl_linux_resolver
 
-	mov ip, r0
-	ldmia sp!, {r0, r1, r2, r3, sl, fp, lr}
-	mov pc,ip
+	mov   ip, r0
+	ldmia sp!, {r0-r3, lr}
+	bx    ip
 .size _dl_linux_resolve, .-_dl_linux_resolve
--- uClibc-0.9.27/ldso/ldso/arm/elfinterp.c	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/ldso/ldso/arm/elfinterp.c	2005-08-13 16:08:19.061345947 -0700
@@ -128,7 +128,7 @@
 
 	rel_addr = (ELF_RELOC *) (tpnt->dynamic_info[DT_JMPREL] + tpnt->loadaddr);
 
-	this_reloc = rel_addr + (reloc_entry >> 3);
+	this_reloc = rel_addr + reloc_entry;
 	reloc_type = ELF32_R_TYPE(this_reloc->r_info);
 	symtab_index = ELF32_R_SYM(this_reloc->r_info);
 
@@ -149,13 +149,20 @@
 	got_addr = (char **) instr_addr;
 
 	/* Get the address of the GOT entry */
-	new_addr = _dl_find_hash(symname, tpnt->symbol_scope,
-				 tpnt, ELF_RTYPE_CLASS_PLT);
-	if (unlikely(!new_addr)) {
-		_dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
-			_dl_progname, symname);
-		_dl_exit(1);
-	};
+	new_addr = _dl_find_hash(symname, tpnt->symbol_scope, tpnt,
+		ELF_RTYPE_CLASS_PLT+ELF_RTYPE_CLASS_OF(STT_FUNC));
+	if (!new_addr) {
+		new_addr = _dl_find_hash(symname, tpnt->symbol_scope, tpnt,
+			ELF_RTYPE_CLASS_PLT+ELF_RTYPE_CLASS_OF(STT_ARM_TFUNC));
+		if (new_addr) {
+			/* Fix up the address for thumb. */
+			new_addr = (char*)((unsigned long)new_addr | 1);
+		} else {
+			_dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
+				_dl_progname, symname);
+			_dl_exit(1);
+		}
+	}
 #if defined (__SUPPORT_LD_DEBUG__)
 	if ((unsigned long) got_addr < 0x40000000)
 	{
@@ -278,7 +285,8 @@
 	if (symtab_index) {
 
 		symbol_addr = (unsigned long) _dl_find_hash(strtab + symtab[symtab_index].st_name,
-				scope, tpnt, elf_machine_type_class(reloc_type));
+				scope, tpnt, elf_machine_type_class(reloc_type) +
+				ELF_RTYPE_CLASS_DEFAULT + ELF_RTYPE_CLASS_OF(STT_ARM_TFUNC));
 
 		/*
 		 * We want to allow undefined references to weak symbols - this might
--- uClibc-0.9.27/ldso/ldso/dl-hash.c	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/ldso/ldso/dl-hash.c	2005-08-12 18:28:05.000000000 -0700
@@ -148,7 +148,11 @@
 	char *weak_result = NULL;
 
 	elf_hash_number = _dl_elf_hash(name);
-	   
+	/* The type class argument may specify the valid symbol types, if not
+	 * any type <= STT_FUNC is permitted.
+	 */
+	if ((type_class & ELF_RTYPE_CLASS_ALL) == 0)
+		type_class += ELF_RTYPE_CLASS_DEFAULT;
 	for (; rpnt; rpnt = rpnt->next) {
 		tpnt = rpnt->dyn;
 
@@ -178,13 +182,16 @@
 		for (si = tpnt->elf_buckets[hn]; si != STN_UNDEF; si = tpnt->chains[si]) {
 			sym = &symtab[si];
 
+			/*... nb, ELF_RTYPE_CLASS_PLT is, must be, "1" - at least
+			 * it must be for the following to work.
+			 */
 			if (type_class & (sym->st_shndx == SHN_UNDEF))
 				continue;
-			if (_dl_strcmp(strtab + sym->st_name, name) != 0)
-				continue;
 			if (sym->st_value == 0)
 				continue;
-			if (ELF32_ST_TYPE(sym->st_info) > STT_FUNC)
+			if ((ELF_RTYPE_CLASS_OF(ELF32_ST_TYPE(sym->st_info)) & type_class) == 0)
+				continue;
+			if (_dl_strcmp(strtab + sym->st_name, name) != 0)
 				continue;
 
 			switch (ELF32_ST_BIND(sym->st_info)) {
--- uClibc-0.9.27/libc/sysdeps/linux/arm/clone.S	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/libc/sysdeps/linux/arm/clone.S	2005-08-13 11:56:47.275679748 -0700
@@ -49,12 +49,13 @@
 	swi	__NR_clone
 	movs	a1, a1
 	blt	__syscall_error  (PLT)
-	movne    pc, lr
+	bxne    lr
 
 	@ pick the function arg and call address off the stack and execute
 	ldr	r0, [sp, #4]
+	ldr	ip, [sp]
 	mov	lr, pc
-	ldr 	pc, [sp]
+	bx 	ip
 
 	@ and we are done, passing the return value through r0
 	b	_exit	(PLT)
@@ -70,7 +71,7 @@
 
 	/* return -1 */
 	mvn  r0, $0
-	mov  pc, lr
+	bx   lr
 .size __clone,.-__clone;
 
 .L4:  .word errno
--- uClibc-0.9.27/libc/sysdeps/linux/arm/mmap64.S	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/libc/sysdeps/linux/arm/mmap64.S	2005-08-13 12:20:35.633560643 -0700
@@ -44,7 +44,7 @@
 	mov	ip, r0
 	swi	__NR_mmap2
 	cmn	r0, $4096
-	ldmccfd	sp!, {r4, r5, pc}
+	ldmccfd	sp!, {r4, r5, pc}	@ requires >=5T
 	cmn	r0, $ENOSYS
 	ldmnefd	sp!, {r4, r5, lr}
 	bne	__syscall_error (PLT)
@@ -71,7 +71,7 @@
 
 	/* return -1 */
 	mvn  r0, $0
-	mov  pc, lr
+	bx   lr
 .size mmap64,.-mmap64;
 
 .L4:  .word errno
--- uClibc-0.9.27/libc/sysdeps/linux/arm/vfork.S	2005-01-11 23:59:21.000000000 -0800
+++ uClibc-0.9.27/libc/sysdeps/linux/arm/vfork.S	2005-08-13 12:23:27.500375540 -0700
@@ -37,7 +37,7 @@
 #ifdef __NR_vfork
 		swi		__NR_vfork
 		cmn		r0, #4096
-		movcc	pc, lr
+		bxcc	lr
 
 		/* Check if vfork even exists.  */
 		ldr     r1, =-ENOSYS
@@ -50,7 +50,7 @@
 		cmn     r0, #4096
 
 		/* Syscal worked.  Return to child/parent */
-		movcc   pc, lr
+		bxcc    lr
 
 __syscall_error:
 
@@ -64,7 +64,7 @@
 
 		/* return -1 */
 		mvn  r0, $0
-		mov  pc, lr
+		bx   lr
 
 .L4:  .word errno