MIPS, Tracing: Substitute in_kernel_space() for in_module()

The old in_module() may not work in some situations(e.g. when module &
kernel are in the same address space when CONFIG_MAPPED_KERNEL=y), The
in_kernel_space() is more generic and it is also easy to be implemented
via cloning the existing core_kernel_text(), so, replace the in_module()
with in_kernel_space().

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2005/
Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>

1 files changed, 27 insertions, 27 deletions

diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index 635c1dcdc4fc..5970286131dd 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -17,21 +17,7 @@
 #include <asm/cacheflush.h>
 #include <asm/uasm.h>
 
-/*
- * If the Instruction Pointer is in module space (0xc0000000), return true;
- * otherwise, it is in kernel space (0x80000000), return false.
- *
- * FIXME: This will not work when the kernel space and module space are the
- * same. If they are the same, we need to modify scripts/recordmcount.pl,
- * ftrace_make_nop/call() and the other related parts to ensure the
- * enabling/disabling of the calling site to _mcount is right for both kernel
- * and module.
- */
-
-static inline int in_module(unsigned long ip)
-{
-        return ip & 0x40000000;
-}
+#include <asm-generic/sections.h>
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
@@ -69,6 +55,20 @@ static inline void ftrace_dyn_arch_init_insns(void)
 #endif
 }
 
+/*
+ * Check if the address is in kernel space
+ *
+ * Clone core_kernel_text() from kernel/extable.c, but doesn't call
+ * init_kernel_text() for Ftrace doesn't trace functions in init sections.
+ */
+static inline int in_kernel_space(unsigned long ip)
+{
+        if (ip >= (unsigned long)_stext &&
+            ip <= (unsigned long)_etext)
+                return 1;
+        return 0;
+}
+
 static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
 {
         int faulted;
@@ -91,10 +91,16 @@ int ftrace_make_nop(struct module *mod,
         unsigned long ip = rec->ip;
 
         /*
-         * We have compiled module with -mlong-calls, but compiled the kernel
-         * without it, we need to cope with them respectively.
+         * If ip is in kernel space, no long call, otherwise, long call is
+         * needed.
          */
-        if (in_module(ip)) {
+        if (in_kernel_space(ip)) {
+                /*
+                 * move at, ra
+                 * jal _mcount          --> nop
+                 */
+                new = INSN_NOP;
+        } else {
 #if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
                 /*
                  * lui v1, hi_16bit_of_mcount        --> b 1f (0x10000005)
@@ -117,12 +123,6 @@ int ftrace_make_nop(struct module *mod,
                  */
                 new = INSN_B_1F_4;
 #endif
-        } else {
-                /*
-                 * move at, ra
-                 * jal _mcount          --> nop
-                 */
-                new = INSN_NOP;
         }
         return ftrace_modify_code(ip, new);
 }
@@ -132,8 +132,8 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
         unsigned int new;
         unsigned long ip = rec->ip;
 
-        /* ip, module: 0xc0000000, kernel: 0x80000000 */
-        new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
+        new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
+                insn_lui_v1_hi16_mcount;
 
         return ftrace_modify_code(ip, new);
 }
@@ -204,7 +204,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
          * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
          * kernel, move after the instruction "move ra, at"(offset is 16)
          */
-        ip = self_addr - (in_module(self_addr) ? 24 : 16);
+        ip = self_addr - (in_kernel_space(self_addr) ? 16 : 24);
 
         /*
          * search the text until finding the non-store instruction or "s{d,w}