drivers/xen/xenfs/xensyms.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/init.h>
   3 #include <linux/seq_file.h>
   4 #include <linux/fs.h>
   5 #include <linux/mm.h>
   6 #include <linux/proc_fs.h>
   7 #include <linux/slab.h>
   8 #include <xen/interface/platform.h>
   9 #include <asm/xen/hypercall.h>
  10 #include <xen/xen-ops.h>
  11 #include "xenfs.h"
  12
  13
  14 #define XEN_KSYM_NAME_LEN 127 /* Hypervisor may have different name length */
  15
  16 struct xensyms {
  17         struct xen_platform_op op;
  18         char *name;
  19         uint32_t namelen;
  20 };
  21
  22 /* Grab next output page from the hypervisor */
  23 static int xensyms_next_sym(struct xensyms *xs)
  24 {
  25         int ret;
  26         struct xenpf_symdata *symdata = &xs->op.u.symdata;
  27         uint64_t symnum;
  28
  29         memset(xs->name, 0, xs->namelen);
  30         symdata->namelen = xs->namelen;
  31
  32         symnum = symdata->symnum;
  33
  34         ret = HYPERVISOR_platform_op(&xs->op);
  35         if (ret < 0)
  36                 return ret;
  37
  38         /*
  39          * If hypervisor's symbol didn't fit into the buffer then allocate
  40          * a larger buffer and try again.
  41          */
  42         if (unlikely(symdata->namelen > xs->namelen)) {
  43                 kfree(xs->name);
  44
  45                 xs->namelen = symdata->namelen;
  46                 xs->name = kzalloc(xs->namelen, GFP_KERNEL);
  47                 if (!xs->name)
  48                         return -ENOMEM;
  49
  50                 set_xen_guest_handle(symdata->name, xs->name);
  51                 symdata->symnum--; /* Rewind */
  52
  53                 ret = HYPERVISOR_platform_op(&xs->op);
  54                 if (ret < 0)
  55                         return ret;
  56         }
  57
  58         if (symdata->symnum == symnum)
  59                 /* End of symbols */
  60                 return 1;
  61
  62         return 0;
  63 }
  64
  65 static void *xensyms_start(struct seq_file *m, loff_t *pos)
  66 {
  67         struct xensyms *xs = (struct xensyms *)m->private;
  68
  69         xs->op.u.symdata.symnum = *pos;
  70
  71         if (xensyms_next_sym(xs))
  72                 return NULL;
  73
  74         return m->private;
  75 }
  76
  77 static void *xensyms_next(struct seq_file *m, void *p, loff_t *pos)
  78 {
  79         struct xensyms *xs = (struct xensyms *)m->private;
  80
  81         xs->op.u.symdata.symnum = ++(*pos);
  82
  83         if (xensyms_next_sym(xs))
  84                 return NULL;
  85
  86         return p;
  87 }
  88
  89 static int xensyms_show(struct seq_file *m, void *p)
  90 {
  91         struct xensyms *xs = (struct xensyms *)m->private;
  92         struct xenpf_symdata *symdata = &xs->op.u.symdata;
  93
  94         seq_printf(m, "%016llx %c %s\n", symdata->address,
  95                    symdata->type, xs->name);
  96
  97         return 0;
  98 }
  99
 100 static void xensyms_stop(struct seq_file *m, void *p)
 101 {
 102 }
 103
 104 static const struct seq_operations xensyms_seq_ops = {
 105         .start = xensyms_start,
 106         .next = xensyms_next,
 107         .show = xensyms_show,
 108         .stop = xensyms_stop,
 109 };
 110
 111 static int xensyms_open(struct inode *inode, struct file *file)
 112 {
 113         struct seq_file *m;
 114         struct xensyms *xs;
 115         int ret;
 116
 117         ret = seq_open_private(file, &xensyms_seq_ops,
 118                                sizeof(struct xensyms));
 119         if (ret)
 120                 return ret;
 121
 122         m = file->private_data;
 123         xs = (struct xensyms *)m->private;
 124
 125         xs->namelen = XEN_KSYM_NAME_LEN + 1;
 126         xs->name = kzalloc(xs->namelen, GFP_KERNEL);
 127         if (!xs->name) {
 128                 seq_release_private(inode, file);
 129                 return -ENOMEM;
 130         }
 131         set_xen_guest_handle(xs->op.u.symdata.name, xs->name);
 132         xs->op.cmd = XENPF_get_symbol;
 133         xs->op.u.symdata.namelen = xs->namelen;
 134
 135         return 0;
 136 }
 137
 138 static int xensyms_release(struct inode *inode, struct file *file)
 139 {
 140         struct seq_file *m = file->private_data;
 141         struct xensyms *xs = (struct xensyms *)m->private;
 142
 143         kfree(xs->name);
 144         return seq_release_private(inode, file);
 145 }
 146
 147 const struct file_operations xensyms_ops = {
 148         .open = xensyms_open,
 149         .read = seq_read,
 150         .llseek = seq_lseek,
 151         .release = xensyms_release
 152 };