Merge branch 'sh/dwarf-unwinder' of git://github.com/mfleming/linux-2.6 into sh/dwarf-unwinder

3 files changed, 180 insertions, 47 deletions

diff --git a/arch/sh/include/asm/dwarf.h b/arch/sh/include/asm/dwarf.h
index c367ed3373c5..eef87539963d 100644
--- a/arch/sh/include/asm/dwarf.h
+++ b/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
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 577302f31e6a..f242cd120cf1 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/arch/sh/kernel/dwarf.c
@@ -530,7 +530,18 @@ 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
  *
@@ -548,9 +559,9 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
         unsigned long addr;
 
         /*
-         * If this is the first invocation of this recursive function we
-         * need get the contents of a physical register to get the CFA
-         * in order to begin the virtual unwinding of the stack.
+         * If we're starting at the top of the stack we need get the
+         * contents of a physical register to get the CFA in order to
+         * 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.
@@ -572,9 +583,8 @@ 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
-                 * recursion. There's two reasons why we might exit
-                 * here,
+                 * This is our normal exit path. There are two reasons
+                 * why we might exit here,
                  *
                  *      a) pc has no asscociated DWARF frame info and so
                  *      we don't know how to unwind this frame. This is
@@ -616,10 +626,10 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 
                 } else {
                         /*
-                         * Again, this is the first invocation of this
-                         * recurisve function. We need to physically
-                         * read the contents of a register in order to
-                         * get the Canonical Frame Address for this
+                         * Again, we're starting from the top of the
+                         * stack. We need to physically read
+                         * the contents of a register in order to get
+                         * the Canonical Frame Address for this
                          * function.
                          */
                         frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
@@ -649,13 +659,12 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
         return frame;
 
 bail:
-        dwarf_frame_free_regs(frame);
-        mempool_free(frame, dwarf_frame_pool);
+        dwarf_free_frame(frame);
         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;
@@ -751,6 +760,8 @@ 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);
@@ -761,7 +772,7 @@ 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;
@@ -810,6 +821,8 @@ 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);
@@ -833,10 +846,8 @@ static void dwarf_unwinder_dump(struct task_struct *task,
         while (1) {
                 frame = dwarf_unwind_stack(return_addr, _frame);
 
-                if (_frame) {
-                        dwarf_frame_free_regs(_frame);
-                        mempool_free(_frame, dwarf_frame_pool);
-                }
+                if (_frame)
+                        dwarf_free_frame(_frame);
 
                 _frame = frame;
 
@@ -846,6 +857,9 @@ 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 = {
@@ -875,15 +889,15 @@ static void dwarf_unwinder_cleanup(void)
 }
 
 /**
- *      dwarf_unwinder_init - initialise the dwarf unwinder
+ *      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
  *
- *      Build the data structures describing the .dwarf_frame section to
- *      make it easier to lookup CIE and FDE entries. Because the
- *      .eh_frame section is packed as tightly as possible it is not
- *      easy to lookup the FDE for a given PC, so we build a list of FDE
- *      and CIE entries that make it easier.
+ *      Parse the information in a .eh_frame section.
  */
-static int __init dwarf_unwinder_init(void)
+int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end,
+                        struct module *mod)
 {
         u32 entry_type;
         void *p, *entry;
@@ -891,29 +905,12 @@ static int __init dwarf_unwinder_init(void)
         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;
+        entry = eh_frame_start;
 
-        dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
-                        sizeof(struct dwarf_frame), 0, SLAB_PANIC, NULL);
-        dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
-                        sizeof(struct dwarf_reg), 0, SLAB_PANIC, NULL);
-
-        dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
-                                          mempool_alloc_slab,
-                                          mempool_free_slab,
-                                          dwarf_frame_cachep);
-
-        dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
-                                         mempool_alloc_slab,
-                                         mempool_free_slab,
-                                         dwarf_reg_cachep);
-
-        while ((char *)entry < __stop_eh_frame) {
+        while ((char *)entry < eh_frame_end) {
                 p = entry;
 
                 count = dwarf_entry_len(p, &len);
@@ -925,6 +922,7 @@ static int __init dwarf_unwinder_init(void)
                          * entry and move to the next one because 'len'
                          * tells us where our next entry is.
                          */
+                        err = -EINVAL;
                         goto out;
                 } else
                         p += count;
@@ -936,13 +934,14 @@ static int __init dwarf_unwinder_init(void)
                 p += 4;
 
                 if (entry_type == DW_EH_FRAME_CIE) {
-                        err = dwarf_parse_cie(entry, p, len, end);
+                        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);
+                        err = dwarf_parse_fde(entry, entry_type, p, len,
+                                              end, mod);
                         if (err < 0)
                                 goto out;
                         else
@@ -955,6 +954,92 @@ static int __init dwarf_unwinder_init(void)
         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
+ *
+ *      Build the data structures describing the .dwarf_frame section to
+ *      make it easier to lookup CIE and FDE entries. Because the
+ *      .eh_frame section is packed as tightly as possible it is not
+ *      easy to lookup the FDE for a given PC, so we build a list of FDE
+ *      and CIE entries that make it easier.
+ */
+static int __init dwarf_unwinder_init(void)
+{
+        int err;
+        INIT_LIST_HEAD(&dwarf_cie_list);
+        INIT_LIST_HEAD(&dwarf_fde_list);
+
+        dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
+                        sizeof(struct dwarf_frame), 0, SLAB_PANIC, NULL);
+        dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
+                        sizeof(struct dwarf_reg), 0, SLAB_PANIC, NULL);
+
+        dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
+                                          mempool_alloc_slab,
+                                          mempool_free_slab,
+                                          dwarf_frame_cachep);
+
+        dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
+                                         mempool_alloc_slab,
+                                         mempool_free_slab,
+                                         dwarf_reg_cachep);
+
+        err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
+        if (err)
+                goto out;
+
         err = unwinder_register(&dwarf_unwinder);
         if (err)
                 goto out;
diff --git a/arch/sh/kernel/module.c b/arch/sh/kernel/module.c
index c2efdcde266f..d297a148d16c 100644
--- a/arch/sh/kernel/module.c
+++ b/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 */
 }