x86/retpoline/ftrace: Convert ftrace assembler indirect jumps

Convert all indirect jumps in ftrace assembler code to use non-speculative
sequences when CONFIG_RETPOLINE is enabled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: thomas.lendacky@amd.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-8-git-send-email-dwmw@amazon.co.uk

2 files changed, 8 insertions, 6 deletions

diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index b6c6468e10bc..4c8440de3355 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -8,6 +8,7 @@
 #include <asm/segment.h>
 #include <asm/export.h>
 #include <asm/ftrace.h>
+#include <asm/nospec-branch.h>
 
 #ifdef CC_USING_FENTRY
 # define function_hook  __fentry__
@@ -197,7 +198,8 @@ ftrace_stub:
         movl    0x4(%ebp), %edx
         subl    $MCOUNT_INSN_SIZE, %eax
 
-        call    *ftrace_trace_function
+        movl    ftrace_trace_function, %ecx
+        CALL_NOSPEC %ecx
 
         popl    %edx
         popl    %ecx
@@ -241,5 +243,5 @@ return_to_handler:
         movl    %eax, %ecx
         popl    %edx
         popl    %eax
-        jmp     *%ecx
+        JMP_NOSPEC %ecx
 #endif
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index c832291d948a..7cb8ba08beb9 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -7,7 +7,7 @@
 #include <asm/ptrace.h>
 #include <asm/ftrace.h>
 #include <asm/export.h>
-
+#include <asm/nospec-branch.h>
 
         .code64
         .section .entry.text, "ax"
@@ -286,8 +286,8 @@ trace:
          * ip and parent ip are used and the list function is called when
          * function tracing is enabled.
          */
-        call   *ftrace_trace_function
-
+        movq ftrace_trace_function, %r8
+        CALL_NOSPEC %r8
         restore_mcount_regs
 
         jmp fgraph_trace
@@ -329,5 +329,5 @@ GLOBAL(return_to_handler)
         movq 8(%rsp), %rdx
         movq (%rsp), %rax
         addq $24, %rsp
-        jmp *%rdi
+        JMP_NOSPEC %rdi
 #endif