On Thu, 06 Jul 2006 13:47:27 +0100
David Howells <[email protected]> wrote:
> From: David Howells <[email protected]>
>
> Add coredump capability for the ELF-FDPIC binfmt.
>
> ..
>
> +static int dump_seek(struct file *file, off_t off)
> +{
> + if (file->f_op->llseek) {
> + if (file->f_op->llseek(file, off, 0) != off)
> + return 0;
> + } else {
> + file->f_pos = off;
> + }
> + return 1;
> +}
llseek takes a loff_t and file->f_pos is loff_t. I guess it's a bit moot
on such a CPU. Was it deliberate?
(how come the kernel doesn't have a SEEK_SET #define?)
> +/*
> + * Decide whether a segment is worth dumping; default is yes to be
> + * sure (missing info is worse than too much; etc).
> + * Personally I'd include everything, and use the coredump limit...
> + *
> + * I think we should skip something. But I am not sure how. H.J.
> + */
> +static inline int maydump(struct vm_area_struct *vma)
> +{
> + /* Do not dump I/O mapped devices or special mappings */
> + if (vma->vm_flags & (VM_IO | VM_RESERVED)) {
> + kdcore("%08lx: %08lx: no (IO)", vma->vm_start, vma->vm_flags);
> + return 0;
> + }
> +
> + /* If we may not read the contents, don't allow us to dump
> + * them either. "dump_write()" can't handle it anyway.
> + */
> + if (!(vma->vm_flags & VM_READ)) {
> + kdcore("%08lx: %08lx: no (!read)", vma->vm_start, vma->vm_flags);
> + return 0;
> + }
> +
> + /* Dump shared memory only if mapped from an anonymous file. */
> + if (vma->vm_flags & VM_SHARED) {
> + if (vma->vm_file->f_dentry->d_inode->i_nlink == 0) {
> + kdcore("%08lx: %08lx: no (share)", vma->vm_start, vma->vm_flags);
> + return 1;
> + }
> +
> + kdcore("%08lx: %08lx: no (share)", vma->vm_start, vma->vm_flags);
> + return 0;
> + }
> +
> +#ifdef CONFIG_MMU
> + /* If it hasn't been written to, don't write it out */
> + if (!vma->anon_vma) {
> + kdcore("%08lx: %08lx: no (!anon)", vma->vm_start, vma->vm_flags);
> + return 0;
> + }
> +#endif
> +
> + kdcore("%08lx: %08lx: yes", vma->vm_start, vma->vm_flags);
> + return 1;
> +}
Three callsites - seems too large to inline.
> +#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
The GFS2 tree has
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -32,6 +32,7 @@ #define STACK_MAGIC 0xdeadbeef
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
+#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
#define KERN_EMERG "<0>" /* system is unusable */
Which seems reasonable to me. I'll steal it from them.
> +/* #define DEBUG */
> +
> +#define DUMP_WRITE(addr, nr) \
> + do { if (!dump_write(file, (addr), (nr))) return 0; } while(0)
> +#define DUMP_SEEK(off) \
> + do { if (!dump_seek(file, (off))) return 0; } while(0)
>
> ...
>
> +#undef DUMP_WRITE
> +#undef DUMP_SEEK
> +
> +#define DUMP_WRITE(addr, nr) \
> + if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
> + goto end_coredump;
> +#define DUMP_SEEK(off) \
> + if (!dump_seek(file, (off))) \
> + goto end_coredump;
Embedding returns and gotos in macros is evil. For new code it's worth
doing it vaguely tastefully.
ret = dump_write(...);
if (ret < 0)
goto actually_return_an_error_code;
> + for (vml = current->mm->context.vmlist; vml; vml = vml->next)
> + segs++;
Does this need locking?
-
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