--- a/arch/s390/include/asm/nospec-insn.h
+++ b/arch/s390/include/asm/nospec-insn.h
-@@ -32,10 +32,18 @@
+@@ -29,10 +29,18 @@
__THUNK_PROLOG_NAME __s390x_indirect_jump_r\r2\()use_r\r1
.endm
.macro __THUNK_BRASL r1,r2,r3
brasl \r1,__s390x_indirect_jump_r\r3\()use_r\r2
.endm
-@@ -78,6 +86,23 @@
+@@ -75,6 +83,23 @@
.endif
.endm
+ .endm
+
.macro __THUNK_EX_BR reg,ruse
- # Be very careful when adding instructions to this macro!
- # The ALTERNATIVE replacement code has a .+10 which targets
-@@ -98,12 +123,30 @@
+ #ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
+ exrl 0,555f
+@@ -87,12 +112,30 @@
555: br \reg
.endm
.macro BR_EX reg,ruse=%r1
557: __DECODE_RR __THUNK_BR,\reg,\ruse
.pushsection .s390_indirect_branches,"a",@progbits
-@@ -111,6 +154,13 @@
+@@ -100,6 +143,13 @@
.popsection
.endm
.macro BASR_EX rsave,rtarget,ruse=%r1
559: __DECODE_RRR __THUNK_BRASL,\rsave,\rtarget,\ruse
.pushsection .s390_indirect_branches,"a",@progbits
-@@ -122,10 +172,17 @@
+@@ -111,10 +161,17 @@
.macro GEN_BR_THUNK reg,ruse=%r1
.endm
+++ /dev/null
-From foo@baz Wed May 23 19:42:20 CEST 2018
-From: Martin Schwidefsky <schwidefsky@de.ibm.com>
-Date: Wed, 23 May 2018 18:21:31 +0200
-Subject: s390/ftrace: use expoline for indirect branches
-To: stable@vger.kernel.org
-Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
-Message-ID: <1527092496-24207-5-git-send-email-schwidefsky@de.ibm.com>
-
-From: Martin Schwidefsky <schwidefsky@de.ibm.com>
-
-[ Upstream commit 23a4d7fd34856da8218c4cfc23dba7a6ec0a423a ]
-
-The return from the ftrace_stub, _mcount, ftrace_caller and
-return_to_handler functions is done with "br %r14" and "br %r1".
-These are indirect branches as well and need to use execute
-trampolines for CONFIG_EXPOLINE=y.
-
-The ftrace_caller function is a special case as it returns to the
-start of a function and may only use %r0 and %r1. For a pre z10
-machine the standard execute trampoline uses a LARL + EX to do
-this, but this requires *two* registers in the range %r1..%r15.
-To get around this the 'br %r1' located in the lowcore is used,
-then the EX instruction does not need an address register.
-But the lowcore trick may only be used for pre z14 machines,
-with noexec=on the mapping for the first page may not contain
-instructions. The solution for that is an ALTERNATIVE in the
-expoline THUNK generated by 'GEN_BR_THUNK %r1' to switch to
-EXRL, this relies on the fact that a machine that supports
-noexec=on has EXRL as well.
-
-Cc: stable@vger.kernel.org # 4.16
-Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
-Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- arch/s390/include/asm/nospec-insn.h | 11 +++++++++++
- arch/s390/kernel/asm-offsets.c | 1 +
- arch/s390/kernel/mcount.S | 14 +++++++++-----
- 3 files changed, 21 insertions(+), 5 deletions(-)
-
---- a/arch/s390/include/asm/nospec-insn.h
-+++ b/arch/s390/include/asm/nospec-insn.h
-@@ -2,6 +2,9 @@
- #ifndef _ASM_S390_NOSPEC_ASM_H
- #define _ASM_S390_NOSPEC_ASM_H
-
-+#include <asm/alternative-asm.h>
-+#include <asm/asm-offsets.h>
-+
- #ifdef __ASSEMBLY__
-
- #ifdef CONFIG_EXPOLINE
-@@ -76,13 +79,21 @@
- .endm
-
- .macro __THUNK_EX_BR reg,ruse
-+ # Be very careful when adding instructions to this macro!
-+ # The ALTERNATIVE replacement code has a .+10 which targets
-+ # the "br \reg" after the code has been patched.
- #ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
- exrl 0,555f
- j .
- #else
-+ .ifc \reg,%r1
-+ ALTERNATIVE "ex %r0,_LC_BR_R1", ".insn ril,0xc60000000000,0,.+10", 35
-+ j .
-+ .else
- larl \ruse,555f
- ex 0,0(\ruse)
- j .
-+ .endif
- #endif
- 555: br \reg
- .endm
---- a/arch/s390/kernel/asm-offsets.c
-+++ b/arch/s390/kernel/asm-offsets.c
-@@ -170,6 +170,7 @@ int main(void)
- OFFSET(__LC_MACHINE_FLAGS, _lowcore, machine_flags);
- OFFSET(__LC_GMAP, _lowcore, gmap);
- OFFSET(__LC_PASTE, _lowcore, paste);
-+ OFFSET(__LC_BR_R1, _lowcore, br_r1_trampoline);
- /* software defined ABI-relevant lowcore locations 0xe00 - 0xe20 */
- OFFSET(__LC_DUMP_REIPL, _lowcore, ipib);
- /* hardware defined lowcore locations 0x1000 - 0x18ff */
---- a/arch/s390/kernel/mcount.S
-+++ b/arch/s390/kernel/mcount.S
-@@ -8,12 +8,16 @@
- #include <linux/linkage.h>
- #include <asm/asm-offsets.h>
- #include <asm/ftrace.h>
-+#include <asm/nospec-insn.h>
- #include <asm/ptrace.h>
-
-+ GEN_BR_THUNK %r1
-+ GEN_BR_THUNK %r14
-+
- .section .kprobes.text, "ax"
-
- ENTRY(ftrace_stub)
-- br %r14
-+ BR_EX %r14
-
- #define STACK_FRAME_SIZE (STACK_FRAME_OVERHEAD + __PT_SIZE)
- #define STACK_PTREGS (STACK_FRAME_OVERHEAD)
-@@ -21,7 +25,7 @@ ENTRY(ftrace_stub)
- #define STACK_PTREGS_PSW (STACK_PTREGS + __PT_PSW)
-
- ENTRY(_mcount)
-- br %r14
-+ BR_EX %r14
-
- ENTRY(ftrace_caller)
- .globl ftrace_regs_caller
-@@ -49,7 +53,7 @@ ENTRY(ftrace_caller)
- #endif
- lgr %r3,%r14
- la %r5,STACK_PTREGS(%r15)
-- basr %r14,%r1
-+ BASR_EX %r14,%r1
- #ifdef CONFIG_FUNCTION_GRAPH_TRACER
- # The j instruction gets runtime patched to a nop instruction.
- # See ftrace_enable_ftrace_graph_caller.
-@@ -64,7 +68,7 @@ ftrace_graph_caller_end:
- #endif
- lg %r1,(STACK_PTREGS_PSW+8)(%r15)
- lmg %r2,%r15,(STACK_PTREGS_GPRS+2*8)(%r15)
-- br %r1
-+ BR_EX %r1
-
- #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-
-@@ -77,6 +81,6 @@ ENTRY(return_to_handler)
- aghi %r15,STACK_FRAME_OVERHEAD
- lgr %r14,%r2
- lmg %r2,%r5,32(%r15)
-- br %r14
-+ BR_EX %r14
-
- #endif
projects / thirdparty / kernel / stable-queue.git / commitdiff
