s390/kernel: use expoline for indirect branches

The assember code in arch/s390/kernel uses a few more indirect branches
which need to be done with execute trampolines for CONFIG_EXPOLINE=y.

Cc: stable@vger.kernel.org # 4.16
Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/base.S b/arch/s390/kernel/base.S
index f6c5600..b65874b 100644 (file)
--- a/arch/s390/kernel/base.S
+++ b/arch/s390/kernel/base.S
@@ -9,18 +9,22 @@
 
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
+#include <asm/nospec-insn.h>
 #include <asm/ptrace.h>
 #include <asm/sigp.h>
 
+       GEN_BR_THUNK %r9
+       GEN_BR_THUNK %r14
+
 ENTRY(s390_base_mcck_handler)
        basr    %r13,0
 0:     lg      %r15,__LC_PANIC_STACK   # load panic stack
        aghi    %r15,-STACK_FRAME_OVERHEAD
        larl    %r1,s390_base_mcck_handler_fn
-       lg      %r1,0(%r1)
-       ltgr    %r1,%r1
+       lg      %r9,0(%r1)
+       ltgr    %r9,%r9
        jz      1f
-       basr    %r14,%r1
+       BASR_EX %r14,%r9
 1:     la      %r1,4095
        lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)
        lpswe   __LC_MCK_OLD_PSW
@@ -37,10 +41,10 @@ ENTRY(s390_base_ext_handler)
        basr    %r13,0
 0:     aghi    %r15,-STACK_FRAME_OVERHEAD
        larl    %r1,s390_base_ext_handler_fn
-       lg      %r1,0(%r1)
-       ltgr    %r1,%r1
+       lg      %r9,0(%r1)
+       ltgr    %r9,%r9
        jz      1f
-       basr    %r14,%r1
+       BASR_EX %r14,%r9
 1:     lmg     %r0,%r15,__LC_SAVE_AREA_ASYNC
        ni      __LC_EXT_OLD_PSW+1,0xfd # clear wait state bit
        lpswe   __LC_EXT_OLD_PSW
@@ -57,10 +61,10 @@ ENTRY(s390_base_pgm_handler)
        basr    %r13,0
 0:     aghi    %r15,-STACK_FRAME_OVERHEAD
        larl    %r1,s390_base_pgm_handler_fn
-       lg      %r1,0(%r1)
-       ltgr    %r1,%r1
+       lg      %r9,0(%r1)
+       ltgr    %r9,%r9
        jz      1f
-       basr    %r14,%r1
+       BASR_EX %r14,%r9
        lmg     %r0,%r15,__LC_SAVE_AREA_SYNC
        lpswe   __LC_PGM_OLD_PSW
 1:     lpswe   disabled_wait_psw-0b(%r13)
@@ -117,7 +121,7 @@ ENTRY(diag308_reset)
        larl    %r4,.Lcontinue_psw      # Restore PSW flags
        lpswe   0(%r4)
 .Lcontinue:
-       br      %r14
+       BR_EX   %r14
 .align 16
 .Lrestart_psw:
        .long   0x00080000,0x80000000 + .Lrestart_part2

diff --git a/arch/s390/kernel/reipl.S b/arch/s390/kernel/reipl.S
index 73cc375..7f14adf 100644 (file)
--- a/arch/s390/kernel/reipl.S
+++ b/arch/s390/kernel/reipl.S
@@ -7,8 +7,11 @@
 
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
+#include <asm/nospec-insn.h>
 #include <asm/sigp.h>
 
+       GEN_BR_THUNK %r9
+
 #
 # Issue "store status" for the current CPU to its prefix page
 # and call passed function afterwards
@@ -67,9 +70,9 @@ ENTRY(store_status)
        st      %r4,0(%r1)
        st      %r5,4(%r1)
        stg     %r2,8(%r1)
-       lgr     %r1,%r2
+       lgr     %r9,%r2
        lgr     %r2,%r3
-       br      %r1
+       BR_EX   %r9
 
        .section .bss
        .align  8

diff --git a/arch/s390/kernel/swsusp.S b/arch/s390/kernel/swsusp.S
index e991871..a049a7b 100644 (file)
--- a/arch/s390/kernel/swsusp.S
+++ b/arch/s390/kernel/swsusp.S
@@ -13,6 +13,7 @@
 #include <asm/ptrace.h>
 #include <asm/thread_info.h>
 #include <asm/asm-offsets.h>
+#include <asm/nospec-insn.h>
 #include <asm/sigp.h>
 
 /*
@@ -24,6 +25,8 @@
  * (see below) in the resume process.
  * This function runs with disabled interrupts.
  */
+       GEN_BR_THUNK %r14
+
        .section .text
 ENTRY(swsusp_arch_suspend)
        stmg    %r6,%r15,__SF_GPRS(%r15)
@@ -103,7 +106,7 @@ ENTRY(swsusp_arch_suspend)
        spx     0x318(%r1)
        lmg     %r6,%r15,STACK_FRAME_OVERHEAD + __SF_GPRS(%r15)
        lghi    %r2,0
-       br      %r14
+       BR_EX   %r14
 
 /*
  * Restore saved memory image to correct place and restore register context.
@@ -197,11 +200,10 @@ pgm_check_entry:
        larl    %r15,init_thread_union
        ahi     %r15,1<<(PAGE_SHIFT+THREAD_SIZE_ORDER)
        larl    %r2,.Lpanic_string
-       larl    %r3,sclp_early_printk
        lghi    %r1,0
        sam31
        sigp    %r1,%r0,SIGP_SET_ARCHITECTURE
-       basr    %r14,%r3
+       brasl   %r14,sclp_early_printk
        larl    %r3,.Ldisabled_wait_31
        lpsw    0(%r3)
 4:
@@ -267,7 +269,7 @@ restore_registers:
        /* Return 0 */
        lmg     %r6,%r15,STACK_FRAME_OVERHEAD + __SF_GPRS(%r15)
        lghi    %r2,0
-       br      %r14
+       BR_EX   %r14
 
        .section .data..nosave,"aw",@progbits
        .align  8