x86/entry/64: Merge SAVE_C_REGS and SAVE_EXTRA_REGS, remove unused extensions

All current code paths call SAVE_C_REGS and then immediately
SAVE_EXTRA_REGS. Therefore, merge these two macros and order the MOV
sequeneces properly.

While at it, remove the macros to save all except specific registers,
as these macros have been unused for a long time.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180211104949.12992-2-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 19 insertions, 50 deletions

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index f4b129d4af42..8907a6593b42 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -101,49 +101,22 @@ For 32-bit we have the following conventions - kernel is built with
         addq    $-(15*8), %rsp
         .endm
 
-        .macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1
-        .if \r11
-        movq %r11, 6*8+\offset(%rsp)
-        .endif
-        .if \r8910
-        movq %r10, 7*8+\offset(%rsp)
-        movq %r9,  8*8+\offset(%rsp)
-        movq %r8,  9*8+\offset(%rsp)
-        .endif
-        .if \rax
-        movq %rax, 10*8+\offset(%rsp)
-        .endif
-        .if \rcx
-        movq %rcx, 11*8+\offset(%rsp)
-        .endif
-        movq %rdx, 12*8+\offset(%rsp)
-        movq %rsi, 13*8+\offset(%rsp)
+        .macro SAVE_REGS offset=0
         movq %rdi, 14*8+\offset(%rsp)
-        UNWIND_HINT_REGS offset=\offset extra=0
-        .endm
-        .macro SAVE_C_REGS offset=0
-        SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1
-        .endm
-        .macro SAVE_C_REGS_EXCEPT_RAX_RCX offset=0
-        SAVE_C_REGS_HELPER \offset, 0, 0, 1, 1
-        .endm
-        .macro SAVE_C_REGS_EXCEPT_R891011
-        SAVE_C_REGS_HELPER 0, 1, 1, 0, 0
-        .endm
-        .macro SAVE_C_REGS_EXCEPT_RCX_R891011
-        SAVE_C_REGS_HELPER 0, 1, 0, 0, 0
-        .endm
-        .macro SAVE_C_REGS_EXCEPT_RAX_RCX_R11
-        SAVE_C_REGS_HELPER 0, 0, 0, 1, 0
-        .endm
-
-        .macro SAVE_EXTRA_REGS offset=0
-        movq %r15, 0*8+\offset(%rsp)
-        movq %r14, 1*8+\offset(%rsp)
-        movq %r13, 2*8+\offset(%rsp)
-        movq %r12, 3*8+\offset(%rsp)
-        movq %rbp, 4*8+\offset(%rsp)
+        movq %rsi, 13*8+\offset(%rsp)
+        movq %rdx, 12*8+\offset(%rsp)
+        movq %rcx, 11*8+\offset(%rsp)
+        movq %rax, 10*8+\offset(%rsp)
+        movq %r8,  9*8+\offset(%rsp)
+        movq %r9,  8*8+\offset(%rsp)
+        movq %r10, 7*8+\offset(%rsp)
+        movq %r11, 6*8+\offset(%rsp)
         movq %rbx, 5*8+\offset(%rsp)
+        movq %rbp, 4*8+\offset(%rsp)
+        movq %r12, 3*8+\offset(%rsp)
+        movq %r13, 2*8+\offset(%rsp)
+        movq %r14, 1*8+\offset(%rsp)
+        movq %r15, 0*8+\offset(%rsp)
         UNWIND_HINT_REGS offset=\offset
         .endm
 
@@ -197,7 +170,7 @@ For 32-bit we have the following conventions - kernel is built with
  * is just setting the LSB, which makes it an invalid stack address and is also
  * a signal to the unwinder that it's a pt_regs pointer in disguise.
  *
- * NOTE: This macro must be used *after* SAVE_EXTRA_REGS because it corrupts
+ * NOTE: This macro must be used *after* SAVE_REGS because it corrupts
  * the original rbp.
  */
 .macro ENCODE_FRAME_POINTER ptregs_offset=0
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 932a445febee..1a6fc0136225 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -573,8 +573,7 @@ END(irq_entries_start)
 1:
 
         ALLOC_PT_GPREGS_ON_STACK
-        SAVE_C_REGS
-        SAVE_EXTRA_REGS
+        SAVE_REGS
         CLEAR_REGS_NOSPEC
         ENCODE_FRAME_POINTER
 
@@ -1132,8 +1131,7 @@ ENTRY(xen_failsafe_callback)
         UNWIND_HINT_IRET_REGS
         pushq   $-1 /* orig_ax = -1 => not a system call */
         ALLOC_PT_GPREGS_ON_STACK
-        SAVE_C_REGS
-        SAVE_EXTRA_REGS
+        SAVE_REGS
         CLEAR_REGS_NOSPEC
         ENCODE_FRAME_POINTER
         jmp     error_exit
@@ -1178,8 +1176,7 @@ idtentry machine_check		do_mce			has_error_code=0	paranoid=1
 ENTRY(paranoid_entry)
         UNWIND_HINT_FUNC
         cld
-        SAVE_C_REGS 8
-        SAVE_EXTRA_REGS 8
+        SAVE_REGS 8
         CLEAR_REGS_NOSPEC
         ENCODE_FRAME_POINTER 8
         movl    $1, %ebx
@@ -1231,8 +1228,7 @@ END(paranoid_exit)
 ENTRY(error_entry)
         UNWIND_HINT_FUNC
         cld
-        SAVE_C_REGS 8
-        SAVE_EXTRA_REGS 8
+        SAVE_REGS 8
         CLEAR_REGS_NOSPEC
         ENCODE_FRAME_POINTER 8
         testb   $3, CS+8(%rsp)