[PATCH v2 01/13] Export hypervisor symbols

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

Export Xen's symbols in format similar to Linux' /proc/kallsyms.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 xen/arch/x86/platform_hypercall.c        |  9 +++++
 xen/arch/x86/x86_64/platform_hypercall.c |  2 +-
 xen/common/symbols-dummy.c               |  1 +
 xen/common/symbols.c                     | 58 ++++++++++++++++++++++++++++++--
 xen/include/public/platform.h            | 22 ++++++++++++
 xen/include/xen/symbols.h                |  4 +++
 xen/tools/symbols.c                      |  4 +++
 7 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/platform_hypercall.c b/xen/arch/x86/platform_hypercall.c
index 7175a82..39376fe 100644
--- a/xen/arch/x86/platform_hypercall.c
+++ b/xen/arch/x86/platform_hypercall.c
@@ -23,6 +23,7 @@
 #include <xen/cpu.h>
 #include <xen/pmstat.h>
 #include <xen/irq.h>
+#include <xen/symbols.h>
 #include <asm/current.h>
 #include <public/platform.h>
 #include <acpi/cpufreq/processor_perf.h>
@@ -597,6 +598,14 @@ ret_t do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
     }
     break;
 
+    case XENPF_get_symbols:
+    {
+        ret = xensyms_read(&op->u.symdata);
+        if ( ret >= 0 && __copy_field_to_guest(u_xenpf_op, op, u.symdata) )
+            ret = -EFAULT;
+    }
+    break;
+ 
     default:
         ret = -ENOSYS;
         break;
diff --git a/xen/arch/x86/x86_64/platform_hypercall.c b/xen/arch/x86/x86_64/platform_hypercall.c
index aa2ad54..9ef705a 100644
--- a/xen/arch/x86/x86_64/platform_hypercall.c
+++ b/xen/arch/x86/x86_64/platform_hypercall.c
@@ -35,7 +35,7 @@ CHECK_pf_pcpu_version;
 #undef xen_pf_pcpu_version
 
 #define xenpf_enter_acpi_sleep compat_pf_enter_acpi_sleep
-
+#define xenpf_symdata	compat_pf_symdata
 #define COMPAT
 #define _XEN_GUEST_HANDLE(t) XEN_GUEST_HANDLE(t)
 #define _XEN_GUEST_HANDLE_PARAM(t) XEN_GUEST_HANDLE_PARAM(t)
diff --git a/xen/common/symbols-dummy.c b/xen/common/symbols-dummy.c
index 5090c3b..52a86c7 100644
--- a/xen/common/symbols-dummy.c
+++ b/xen/common/symbols-dummy.c
@@ -12,6 +12,7 @@ const unsigned int symbols_offsets[1];
 const unsigned long symbols_addresses[1];
 #endif
 const unsigned int symbols_num_syms;
+const unsigned long symbols_names_bytes;
 const u8 symbols_names[1];
 
 const u8 symbols_token_table[1];
diff --git a/xen/common/symbols.c b/xen/common/symbols.c
index 83b2b58..e74a585 100644
--- a/xen/common/symbols.c
+++ b/xen/common/symbols.c
@@ -17,6 +17,8 @@
 #include <xen/lib.h>
 #include <xen/string.h>
 #include <xen/spinlock.h>
+#include <public/platform.h>
+#include <xen/guest_access.h>
 
 #ifdef SYMBOLS_ORIGIN
 extern const unsigned int symbols_offsets[1];
@@ -26,6 +28,7 @@ extern const unsigned long symbols_addresses[];
 #define symbols_address(n) symbols_addresses[n]
 #endif
 extern const unsigned int symbols_num_syms;
+extern const unsigned long symbols_names_bytes;
 extern const u8 symbols_names[];
 
 extern const u8 symbols_token_table[];
@@ -35,7 +38,8 @@ extern const unsigned int symbols_markers[];
 
 /* expand a compressed symbol data into the resulting uncompressed string,
    given the offset to where the symbol is in the compressed stream */
-static unsigned int symbols_expand_symbol(unsigned int off, char *result)
+static unsigned int symbols_expand_symbol(unsigned int off, char *result,
+                                          int maxlen)
 {
     int len, skipped_first = 0;
     const u8 *tptr, *data;
@@ -49,6 +53,9 @@ static unsigned int symbols_expand_symbol(unsigned int off, char *result)
      * the compressed stream */
     off += len + 1;
 
+    if (maxlen < len)
+        len = maxlen;
+
     /* for every byte on the compressed symbol data, copy the table
        entry for that byte */
     while(len) {
@@ -129,7 +136,7 @@ const char *symbols_lookup(unsigned long addr,
         --low;
 
         /* Grab name */
-    symbols_expand_symbol(get_symbol_offset(low), namebuf);
+    symbols_expand_symbol(get_symbol_offset(low), namebuf, sizeof(namebuf));
 
     /* Search for next non-aliased symbol */
     for (i = low + 1; i < symbols_num_syms; i++) {
@@ -174,3 +181,50 @@ void __print_symbol(const char *fmt, unsigned long address)
 
     spin_unlock_irqrestore(&lock, flags);
 }
+
+/*
+ * Get symbol type information. This is encoded as a single char at the
+ * beginning of the symbol name.
+ */
+static char symbols_get_symbol_type(unsigned int off)
+{
+    /*
+     * Get just the first code, look it up in the token table,
+     * and return the first char from this token.
+     */
+    return symbols_token_table[symbols_token_index[symbols_names[off + 1]]];
+}
+
+/*
+ * Symbols are most likely accessed sequentially so we remember position from
+ * previous read. This can help us avoid extra call to get_symbol_offset().
+ */
+static uint64_t next_symbol, next_offset;
+static DEFINE_SPINLOCK(symbols_mutex);
+
+int xensyms_read(struct xenpf_symdata *symdata)
+{
+    if ( symdata->xen_symnum > symbols_num_syms )
+        return -EINVAL;
+    else if ( symdata->xen_symnum == symbols_num_syms )
+        return 0;
+
+    spin_lock(&symbols_mutex);
+
+    if ( symdata->xen_symnum == 0 )
+        next_offset = next_symbol = 0;
+    else if ( next_symbol != symdata->xen_symnum )
+        /* Non-sequential access */
+        next_offset = get_symbol_offset(symdata->xen_symnum);
+
+    symdata->type = symbols_get_symbol_type(next_offset);
+    next_offset = symbols_expand_symbol(next_offset, symdata->name,
+        sizeof(symdata->name));
+    symdata->address = symbols_offsets[symdata->xen_symnum] + SYMBOLS_ORIGIN;
+
+    next_symbol = symdata->xen_symnum + 1;
+
+    spin_unlock(&symbols_mutex);
+
+    return strlen(symdata->name);
+}
diff --git a/xen/include/public/platform.h b/xen/include/public/platform.h
index 4341f54..870e14b 100644
--- a/xen/include/public/platform.h
+++ b/xen/include/public/platform.h
@@ -527,6 +527,27 @@ struct xenpf_core_parking {
 typedef struct xenpf_core_parking xenpf_core_parking_t;
 DEFINE_XEN_GUEST_HANDLE(xenpf_core_parking_t);
 
+#define XENPF_get_symbols  61
+
+struct xenpf_symdata {
+    /* IN variables */
+    uint64_t xen_symnum;
+
+    /* OUT variables */
+    uint64_t address;
+    uint64_t type;
+    /*
+     * KSYM_NAME_LEN is 128 bytes. However, we cannot be larger than pad in
+     * xen_platform_op below (which is 128 bytes as well). Since the largest
+     * symbol is around 50 bytes it's probably more trouble than it's worth
+     * to try to deal with symbols that are close to 128 bytes in length.
+     */
+#define XEN_SYMS_MAX_LEN (128 - 3 * 8)
+    char name[XEN_SYMS_MAX_LEN];
+};
+typedef struct xenpf_symdata xenpf_symdata_t;
+DEFINE_XEN_GUEST_HANDLE(xenpf_symdata_t);
+
 /*
  * ` enum neg_errnoval
  * ` HYPERVISOR_platform_op(const struct xen_platform_op*);
@@ -553,6 +574,7 @@ struct xen_platform_op {
         struct xenpf_cpu_hotadd        cpu_add;
         struct xenpf_mem_hotadd        mem_add;
         struct xenpf_core_parking      core_parking;
+        struct xenpf_symdata           symdata;
         uint8_t                        pad[128];
     } u;
 };
diff --git a/xen/include/xen/symbols.h b/xen/include/xen/symbols.h
index 37cf6bf..c8df28f 100644
--- a/xen/include/xen/symbols.h
+++ b/xen/include/xen/symbols.h
@@ -2,6 +2,8 @@
 #define _XEN_SYMBOLS_H
 
 #include <xen/types.h>
+#include <public/xen.h>
+#include <public/platform.h>
 
 #define KSYM_NAME_LEN 127
 
@@ -34,4 +36,6 @@ do {						\
 	__print_symbol(fmt, addr);		\
 } while(0)
 
+extern int xensyms_read(struct xenpf_symdata *symdata);
+
 #endif /*_XEN_SYMBOLS_H*/
diff --git a/xen/tools/symbols.c b/xen/tools/symbols.c
index f39c906..818204d 100644
--- a/xen/tools/symbols.c
+++ b/xen/tools/symbols.c
@@ -272,6 +272,10 @@ static void write_src(void)
 	}
 	printf("\n");
 
+	output_label("symbols_names_bytes");
+	printf("\t.long\t%d\n", off);
+	printf("\n");
+
 	output_label("symbols_markers");
 	for (i = 0; i < ((table_cnt + 255) >> 8); i++)
 		printf("\t.long\t%d\n", markers[i]);
-- 
1.8.1.4