Merge branch 'sh/dwarf-unwinder'

Conflicts:
	arch/sh/kernel/dwarf.c

arch/sh/include/asm/dwarf.h

@@ -241,6 +241,12 @@ struct dwarf_cie {
 
 	unsigned long flags;
 #define DWARF_CIE_Z_AUGMENTATION	(1 << 0)
+
+	/*
+	 * 'mod' will be non-NULL if this CIE came from a module's
+	 * .eh_frame section.
+	 */
+	struct module *mod;
 };
 
 /**
@@ -255,6 +261,12 @@ struct dwarf_fde {
 	unsigned char *instructions;
 	unsigned char *end;
 	struct list_head link;
+
+	/*
+	 * 'mod' will be non-NULL if this FDE came from a module's
+	 * .eh_frame section.
+	 */
+	struct module *mod;
 };
 
 /**
@@ -364,6 +376,10 @@ static inline unsigned int DW_CFA_operand(unsigned long insn)
 
 extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
 					      struct dwarf_frame *);
+extern void dwarf_free_frame(struct dwarf_frame *);
+extern int dwarf_parse_section(char *, char *, struct module *);
+extern void dwarf_module_unload(struct module *);
+
 #endif /* !__ASSEMBLY__ */
 
 #define CFI_STARTPROC	.cfi_startproc

arch/sh/kernel/dwarf.c

@@ -529,7 +529,18 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
 }
 
 /**
- *	dwarf_unwind_stack - recursively unwind the stack
+ *	dwarf_free_frame - free the memory allocated for @frame
+ *	@frame: the frame to free
+ */
+void dwarf_free_frame(struct dwarf_frame *frame)
+{
+	dwarf_frame_free_regs(frame);
+	mempool_free(frame, dwarf_frame_pool);
+}
+
+/**
+ *	dwarf_unwind_stack - unwind the stack
+ *
  *	@pc: address of the function to unwind
  *	@prev: struct dwarf_frame of the previous stackframe on the callstack
  *
@@ -547,9 +558,9 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 	unsigned long addr;
 
 	/*
-	 * If this is the first invocation of this recursive function we
+	 * If we're starting at the top of the stack we need get the
-	 * need get the contents of a physical register to get the CFA
+	 * contents of a physical register to get the CFA in order to
-	 * in order to begin the virtual unwinding of the stack.
+	 * begin the virtual unwinding of the stack.
 	 *
 	 * NOTE: the return address is guaranteed to be setup by the
 	 * time this function makes its first function call.
@@ -571,9 +582,8 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 	fde = dwarf_lookup_fde(pc);
 	if (!fde) {
 		/*
-		 * This is our normal exit path - the one that stops the
+		 * This is our normal exit path. There are two reasons
-		 * recursion. There's two reasons why we might exit
+		 * why we might exit here,
-		 * here,
 		 *
 		 *	a) pc has no asscociated DWARF frame info and so
 		 *	we don't know how to unwind this frame. This is
@@ -615,10 +625,10 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 
 		} else {
 			/*
-			 * Again, this is the first invocation of this
+			 * Again, we're starting from the top of the
-			 * recurisve function. We need to physically
+			 * stack. We need to physically read
-			 * read the contents of a register in order to
+			 * the contents of a register in order to get
-			 * get the Canonical Frame Address for this
+			 * the Canonical Frame Address for this
 			 * function.
 			 */
 			frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
@@ -648,13 +658,12 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 	return frame;
 
 bail:
-	dwarf_frame_free_regs(frame);
+	dwarf_free_frame(frame);
-	mempool_free(frame, dwarf_frame_pool);
 	return NULL;
 }
 
 static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
-			   unsigned char *end)
+			   unsigned char *end, struct module *mod)
 {
 	struct dwarf_cie *cie;
 	unsigned long flags;
@@ -750,6 +759,8 @@ static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
 	cie->initial_instructions = p;
 	cie->instructions_end = end;
 
+	cie->mod = mod;
+
 	/* Add to list */
 	spin_lock_irqsave(&dwarf_cie_lock, flags);
 	list_add_tail(&cie->link, &dwarf_cie_list);
@@ -760,7 +771,7 @@ static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
 
 static int dwarf_parse_fde(void *entry, u32 entry_type,
 			   void *start, unsigned long len,
-			   unsigned char *end)
+			   unsigned char *end, struct module *mod)
 {
 	struct dwarf_fde *fde;
 	struct dwarf_cie *cie;
@@ -809,6 +820,8 @@ static int dwarf_parse_fde(void *entry, u32 entry_type,
 	fde->instructions = p;
 	fde->end = end;
 
+	fde->mod = mod;
+
 	/* Add to list. */
 	spin_lock_irqsave(&dwarf_fde_lock, flags);
 	list_add_tail(&fde->link, &dwarf_fde_list);
@@ -832,10 +845,8 @@ static void dwarf_unwinder_dump(struct task_struct *task,
 	while (1) {
 		frame = dwarf_unwind_stack(return_addr, _frame);
 
-		if (_frame) {
+		if (_frame)
-			dwarf_frame_free_regs(_frame);
+			dwarf_free_frame(_frame);
-			mempool_free(_frame, dwarf_frame_pool);
-		}
 
 		_frame = frame;
 
@@ -845,6 +856,9 @@ static void dwarf_unwinder_dump(struct task_struct *task,
 		return_addr = frame->return_addr;
 		ops->address(data, return_addr, 1);
 	}
+
+	if (frame)
+		dwarf_free_frame(frame);
 }
 
 static struct unwinder dwarf_unwinder = {
@@ -873,6 +887,124 @@ static void dwarf_unwinder_cleanup(void)
 	kmem_cache_destroy(dwarf_frame_cachep);
 }
 
+/**
+ *	dwarf_parse_section - parse DWARF section
+ *	@eh_frame_start: start address of the .eh_frame section
+ *	@eh_frame_end: end address of the .eh_frame section
+ *	@mod: the kernel module containing the .eh_frame section
+ *
+ *	Parse the information in a .eh_frame section.
+ */
+int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end,
+			struct module *mod)
+{
+	u32 entry_type;
+	void *p, *entry;
+	int count, err = 0;
+	unsigned long len;
+	unsigned int c_entries, f_entries;
+	unsigned char *end;
+
+	c_entries = 0;
+	f_entries = 0;
+	entry = eh_frame_start;
+
+	while ((char *)entry < eh_frame_end) {
+		p = entry;
+
+		count = dwarf_entry_len(p, &len);
+		if (count == 0) {
+			/*
+			 * We read a bogus length field value. There is
+			 * nothing we can do here apart from disabling
+			 * the DWARF unwinder. We can't even skip this
+			 * entry and move to the next one because 'len'
+			 * tells us where our next entry is.
+			 */
+			err = -EINVAL;
+			goto out;
+		} else
+			p += count;
+
+		/* initial length does not include itself */
+		end = p + len;
+
+		entry_type = get_unaligned((u32 *)p);
+		p += 4;
+
+		if (entry_type == DW_EH_FRAME_CIE) {
+			err = dwarf_parse_cie(entry, p, len, end, mod);
+			if (err < 0)
+				goto out;
+			else
+				c_entries++;
+		} else {
+			err = dwarf_parse_fde(entry, entry_type, p, len,
+					      end, mod);
+			if (err < 0)
+				goto out;
+			else
+				f_entries++;
+		}
+
+		entry = (char *)entry + len + 4;
+	}
+
+	printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
+	       c_entries, f_entries);
+
+	return 0;
+
+out:
+	return err;
+}
+
+/**
+ *	dwarf_module_unload - remove FDE/CIEs associated with @mod
+ *	@mod: the module that is being unloaded
+ *
+ *	Remove any FDEs and CIEs from the global lists that came from
+ *	@mod's .eh_frame section because @mod is being unloaded.
+ */
+void dwarf_module_unload(struct module *mod)
+{
+	struct dwarf_fde *fde;
+	struct dwarf_cie *cie;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dwarf_cie_lock, flags);
+
+again_cie:
+	list_for_each_entry(cie, &dwarf_cie_list, link) {
+		if (cie->mod == mod)
+			break;
+	}
+
+	if (&cie->link != &dwarf_cie_list) {
+		list_del(&cie->link);
+		kfree(cie);
+		goto again_cie;
+	}
+
+	spin_unlock_irqrestore(&dwarf_cie_lock, flags);
+
+	spin_lock_irqsave(&dwarf_fde_lock, flags);
+
+again_fde:
+	list_for_each_entry(fde, &dwarf_fde_list, link) {
+		if (fde->mod == mod)
+			break;
+	}
+
+	if (&fde->link != &dwarf_fde_list) {
+		list_del(&fde->link);
+		kfree(fde);
+		goto again_fde;
+	}
+
+	spin_unlock_irqrestore(&dwarf_fde_lock, flags);
+}
+
 /**
  *	dwarf_unwinder_init - initialise the dwarf unwinder
  *
@@ -884,19 +1016,10 @@ static void dwarf_unwinder_cleanup(void)
  */
 static int __init dwarf_unwinder_init(void)
 {
-	u32 entry_type;
+	int err;
-	void *p, *entry;
-	int count, err = 0;
-	unsigned long len;
-	unsigned int c_entries, f_entries;
-	unsigned char *end;
 	INIT_LIST_HEAD(&dwarf_cie_list);
 	INIT_LIST_HEAD(&dwarf_fde_list);
 
-	c_entries = 0;
-	f_entries = 0;
-	entry = &__start_eh_frame;
-
 	dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
 			sizeof(struct dwarf_frame), 0,
 			SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
@@ -915,47 +1038,9 @@ static int __init dwarf_unwinder_init(void)
 					 mempool_free_slab,
 					 dwarf_reg_cachep);
 
-	while ((char *)entry < __stop_eh_frame) {
+	err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
-		p = entry;
+	if (err)
-
+		goto out;
-		count = dwarf_entry_len(p, &len);
-		if (count == 0) {
-			/*
-			 * We read a bogus length field value. There is
-			 * nothing we can do here apart from disabling
-			 * the DWARF unwinder. We can't even skip this
-			 * entry and move to the next one because 'len'
-			 * tells us where our next entry is.
-			 */
-			goto out;
-		} else
-			p += count;
-
-		/* initial length does not include itself */
-		end = p + len;
-
-		entry_type = get_unaligned((u32 *)p);
-		p += 4;
-
-		if (entry_type == DW_EH_FRAME_CIE) {
-			err = dwarf_parse_cie(entry, p, len, end);
-			if (err < 0)
-				goto out;
-			else
-				c_entries++;
-		} else {
-			err = dwarf_parse_fde(entry, entry_type, p, len, end);
-			if (err < 0)
-				goto out;
-			else
-				f_entries++;
-		}
-
-		entry = (char *)entry + len + 4;
-	}
-
-	printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
-	       c_entries, f_entries);
 
 	err = unwinder_register(&dwarf_unwinder);
 	if (err)

arch/sh/kernel/module.c

@@ -32,6 +32,7 @@
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <asm/unaligned.h>
+#include <asm/dwarf.h>
 
 void *module_alloc(unsigned long size)
 {
@@ -145,10 +146,41 @@ int module_finalize(const Elf_Ehdr *hdr,
 		    const Elf_Shdr *sechdrs,
 		    struct module *me)
 {
+#ifdef CONFIG_DWARF_UNWINDER
+	unsigned int i, err;
+	unsigned long start, end;
+	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+	start = end = 0;
+
+	for (i = 1; i < hdr->e_shnum; i++) {
+		/* Alloc bit cleared means "ignore it." */
+		if ((sechdrs[i].sh_flags & SHF_ALLOC)
+		    && !strcmp(secstrings+sechdrs[i].sh_name, ".eh_frame")) {
+			start = sechdrs[i].sh_addr;
+			end = start + sechdrs[i].sh_size;
+			break;
+		}
+	}
+
+	/* Did we find the .eh_frame section? */
+	if (i != hdr->e_shnum) {
+		err = dwarf_parse_section((char *)start, (char *)end, me);
+		if (err)
+			printk(KERN_WARNING "%s: failed to parse DWARF info\n",
+			       me->name);
+	}
+
+#endif /* CONFIG_DWARF_UNWINDER */
+
 	return module_bug_finalize(hdr, sechdrs, me);
 }
 
 void module_arch_cleanup(struct module *mod)
 {
 	module_bug_cleanup(mod);
+
+#ifdef CONFIG_DWARF_UNWINDER
+	dwarf_module_unload(mod);
+#endif /* CONFIG_DWARF_UNWINDER */
 }