kallsyms: Take callthunks into account

Since the pre-symbol function padding is an integral part of the
symbol make kallsyms report it as part of the symbol by reporting it
as sym-x instead of prev_sym+y.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.409656012@infradead.org

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 60c20f301a6ba2c794c7716c87e7bde61de196e7..cc244c02b4cf69e0d75d4a7baff1eea2b68c4e35 100644 (file)
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -293,6 +293,12 @@ static unsigned long get_symbol_pos(unsigned long addr,
        return low;
 }
 
+#ifdef CONFIG_FUNCTION_PADDING_BYTES
+#define PADDING_BYTES  CONFIG_FUNCTION_PADDING_BYTES
+#else
+#define PADDING_BYTES  0
+#endif
+
 /*
  * Lookup an address but don't bother to find any names.
  */
@@ -300,13 +306,25 @@ int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
                                unsigned long *offset)
 {
        char namebuf[KSYM_NAME_LEN];
+       int ret;
+
+       addr += PADDING_BYTES;
 
        if (is_ksym_addr(addr)) {
                get_symbol_pos(addr, symbolsize, offset);
-               return 1;
+               ret = 1;
+               goto found;
+       }
+
+       ret = !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf);
+       if (!ret) {
+               ret = !!__bpf_address_lookup(addr, symbolsize,
+                                            offset, namebuf);
        }
-       return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
-              !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
+found:
+       if (ret && offset)
+               *offset -= PADDING_BYTES;
+       return ret;
 }
 
 static const char *kallsyms_lookup_buildid(unsigned long addr,
@@ -319,6 +337,8 @@ static const char *kallsyms_lookup_buildid(unsigned long addr,
        namebuf[KSYM_NAME_LEN - 1] = 0;
        namebuf[0] = 0;
 
+       addr += PADDING_BYTES;
+
        if (is_ksym_addr(addr)) {
                unsigned long pos;
 
@@ -348,6 +368,8 @@ static const char *kallsyms_lookup_buildid(unsigned long addr,
 
 found:
        cleanup_symbol_name(namebuf);
+       if (ret && offset)
+               *offset -= PADDING_BYTES;
        return ret;
 }
 
@@ -374,6 +396,8 @@ int lookup_symbol_name(unsigned long addr, char *symname)
        symname[0] = '\0';
        symname[KSYM_NAME_LEN - 1] = '\0';
 
+       addr += PADDING_BYTES;
+
        if (is_ksym_addr(addr)) {
                unsigned long pos;
 
@@ -401,6 +425,8 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
        name[0] = '\0';
        name[KSYM_NAME_LEN - 1] = '\0';
 
+       addr += PADDING_BYTES;
+
        if (is_ksym_addr(addr)) {
                unsigned long pos;
 
@@ -417,6 +443,8 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
                return res;
 
 found:
+       if (offset)
+               *offset -= PADDING_BYTES;
        cleanup_symbol_name(name);
        return 0;
 }
@@ -442,8 +470,15 @@ static int __sprint_symbol(char *buffer, unsigned long address,
        len = strlen(buffer);
        offset -= symbol_offset;
 
-       if (add_offset)
-               len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
+       if (add_offset) {
+               char s = '+';
+
+               if ((long)offset < 0) {
+                       s = '-';
+                       offset = 0UL - offset;
+               }
+               len += sprintf(buffer + len, "%c%#lx/%#lx", s, offset, size);
+       }
 
        if (modname) {
                len += sprintf(buffer + len, " [%s", modname);