[PATCH v5 RESEND 01/17] common/symbols: Export hypervisor symbols to privileged guest

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

Export Xen's symbols as {<address><type><name>} triplet via new XENPF_get_symbol
hypercall

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 xen/arch/x86/platform_hypercall.c        | 18 ++++++++++++
 xen/arch/x86/x86_64/platform_hypercall.c |  2 ++
 xen/common/symbols.c                     | 50 +++++++++++++++++++++++++++++++-
 xen/common/vsprintf.c                    |  2 +-
 xen/include/public/platform.h            | 16 ++++++++++
 xen/include/xen/symbols.h                |  6 ++--
 xen/include/xlat.lst                     |  1 +
 7 files changed, 91 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/platform_hypercall.c b/xen/arch/x86/platform_hypercall.c
index 2162811..0a93037 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>
@@ -601,6 +602,23 @@ ret_t do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
     }
     break;
 
+    case XENPF_get_symbol:
+    {
+        char name[XEN_KSYM_NAME_LEN + 1];
+        XEN_GUEST_HANDLE(char) nameh;
+
+        guest_from_compat_handle(nameh, op->u.symdata.name);
+
+        ret = xensyms_read(&op->u.symdata.symnum, &op->u.symdata.type,
+                           &op->u.symdata.address, name);
+
+        if ( !ret && copy_to_guest(nameh, name, strlen(name)) )
+            ret = -EFAULT;
+        if ( !ret && __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 b6f380e..795837f 100644
--- a/xen/arch/x86/x86_64/platform_hypercall.c
+++ b/xen/arch/x86/x86_64/platform_hypercall.c
@@ -32,6 +32,8 @@ CHECK_pf_pcpu_version;
 CHECK_pf_enter_acpi_sleep;
 #undef xen_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.c b/xen/common/symbols.c
index 45941e1..bc83f76 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];
@@ -107,7 +109,7 @@ const char *symbols_lookup(unsigned long addr,
     unsigned long i, low, high, mid;
     unsigned long symbol_end = 0;
 
-    namebuf[KSYM_NAME_LEN] = 0;
+    namebuf[XEN_KSYM_NAME_LEN] = 0;
     namebuf[0] = 0;
 
     if (!is_active_kernel_text(addr))
@@ -148,3 +150,49 @@ const char *symbols_lookup(unsigned long addr,
     *offset = addr - symbols_address(low);
     return namebuf;
 }
+
+/*
+ * 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 the extra call to get_symbol_offset().
+ */
+static uint64_t next_symbol, next_offset;
+static DEFINE_SPINLOCK(symbols_mutex);
+
+int xensyms_read(uint32_t *symnum, uint32_t *type, uint64_t *address, char *name)
+{
+    if ( *symnum > symbols_num_syms )
+        return -ERANGE;
+    if ( *symnum == symbols_num_syms )
+        return 0;
+
+    spin_lock(&symbols_mutex);
+
+    if ( *symnum == 0 )
+        next_offset = next_symbol = 0;
+    if ( next_symbol != *symnum )
+        /* Non-sequential access */
+        next_offset = get_symbol_offset(*symnum);
+
+    *type = symbols_get_symbol_type(next_offset);
+    next_offset = symbols_expand_symbol(next_offset, name);
+    *address = symbols_offsets[*symnum] + SYMBOLS_ORIGIN;
+
+    next_symbol = ++*symnum;
+
+    spin_unlock(&symbols_mutex);
+
+    return 0;
+}
diff --git a/xen/common/vsprintf.c b/xen/common/vsprintf.c
index 1a6198e..c5ae187 100644
--- a/xen/common/vsprintf.c
+++ b/xen/common/vsprintf.c
@@ -275,7 +275,7 @@ static char *pointer(char *str, char *end, const char **fmt_ptr,
     case 'S': /* Symbol name unconditionally with offset and size */
     {
         unsigned long sym_size, sym_offset;
-        char namebuf[KSYM_NAME_LEN+1];
+        char namebuf[XEN_KSYM_NAME_LEN+1];
 
         /* Advance parents fmt string, as we have consumed 's' or 'S' */
         ++*fmt_ptr;
diff --git a/xen/include/public/platform.h b/xen/include/public/platform.h
index 4341f54..dc09b55 100644
--- a/xen/include/public/platform.h
+++ b/xen/include/public/platform.h
@@ -527,6 +527,21 @@ struct xenpf_core_parking {
 typedef struct xenpf_core_parking xenpf_core_parking_t;
 DEFINE_XEN_GUEST_HANDLE(xenpf_core_parking_t);
 
+#define XENPF_get_symbol   61
+#define XEN_KSYM_NAME_LEN 127
+struct xenpf_symdata {
+    /* IN variables */
+    uint32_t symnum;
+
+    /* OUT variables */
+    uint32_t type;
+    uint64_t address;
+
+    XEN_GUEST_HANDLE(char) name;
+};
+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 +568,7 @@ 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 87cd77d..3017449 100644
--- a/xen/include/xen/symbols.h
+++ b/xen/include/xen/symbols.h
@@ -2,8 +2,7 @@
 #define _XEN_SYMBOLS_H
 
 #include <xen/types.h>
-
-#define KSYM_NAME_LEN 127
+#include <public/platform.h>
 
 /* Lookup an address. */
 const char *symbols_lookup(unsigned long addr,
@@ -11,4 +10,7 @@ const char *symbols_lookup(unsigned long addr,
                            unsigned long *offset,
                            char *namebuf);
 
+int xensyms_read(uint32_t *symnum, uint32_t *type,
+                 uint64_t *address, char *name);
+
 #endif /*_XEN_SYMBOLS_H*/
diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
index 8caede6..6e3994d 100644
--- a/xen/include/xlat.lst
+++ b/xen/include/xlat.lst
@@ -85,6 +85,7 @@
 ?	processor_px			platform.h
 !	psd_package			platform.h
 ?	xenpf_enter_acpi_sleep		platform.h
+!	xenpf_symdata			platform.h
 ?	xenpf_pcpuinfo			platform.h
 ?	xenpf_pcpu_version		platform.h
 !	sched_poll			sched.h
-- 
1.8.3.1