From b17c2baa305cccbd16bafa289fd743cc2db77966 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Sat, 4 Dec 2021 14:43:41 +0100
Subject: [PATCH] x86: Prepare inline-asm for straight-line-speculation
Replace all ret/retq instructions with ASM_RET in preparation of
making it more than a single instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134907.964635458@infradead.org
---
arch/x86/include/asm/linkage.h | 4 ++++
arch/x86/include/asm/paravirt.h | 2 +-
arch/x86/include/asm/qspinlock_paravirt.h | 4 ++--
arch/x86/kernel/alternative.c | 2 +-
arch/x86/kernel/kprobes/core.c | 2 +-
arch/x86/kernel/paravirt.c | 4 ++--
arch/x86/kvm/emulate.c | 4 ++--
arch/x86/lib/error-inject.c | 3 ++-
samples/ftrace/ftrace-direct-modify.c | 4 ++--
samples/ftrace/ftrace-direct-too.c | 2 +-
samples/ftrace/ftrace-direct.c | 2 +-
11 files changed, 19 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index 365111789cc68..ebddec2f3ba86 100644
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -18,6 +18,10 @@
#define __ALIGN_STR __stringify(__ALIGN)
#endif
+#else /* __ASSEMBLY__ */
+
+#define ASM_RET "ret\n\t"
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_LINKAGE_H */
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 21c4a694ca114..ce1148c5620b0 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -671,7 +671,7 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu);
"call " #func ";" \
PV_RESTORE_ALL_CALLER_REGS \
FRAME_END \
- "ret;" \
+ ASM_RET \
".size " PV_THUNK_NAME(func) ", .-" PV_THUNK_NAME(func) ";" \
".popsection")
diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h
index 159622ee06748..1474cf96251dd 100644
--- a/arch/x86/include/asm/qspinlock_paravirt.h
+++ b/arch/x86/include/asm/qspinlock_paravirt.h
@@ -48,7 +48,7 @@ asm (".pushsection .text;"
"jne .slowpath;"
"pop %rdx;"
FRAME_END
- "ret;"
+ ASM_RET
".slowpath: "
"push %rsi;"
"movzbl %al,%esi;"
@@ -56,7 +56,7 @@ asm (".pushsection .text;"
"pop %rsi;"
"pop %rdx;"
FRAME_END
- "ret;"
+ ASM_RET
".size " PV_UNLOCK ", .-" PV_UNLOCK ";"
".popsection");
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 23fb4d51a5da6..175cde66a1aee 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -714,7 +714,7 @@ asm (
" .type int3_magic, @function\n"
"int3_magic:\n"
" movl $1, (%" _ASM_ARG1 ")\n"
-" ret\n"
+ ASM_RET
" .size int3_magic, .-int3_magic\n"
" .popsection\n"
);
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index fce99e249d613..6290712cb36d2 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1051,7 +1051,7 @@ asm(
" addl $4, %esp\n"
" popfl\n"
#endif
- " ret\n"
+ ASM_RET
".size __kretprobe_trampoline, .-__kretprobe_trampoline\n"
);
NOKPROBE_SYMBOL(__kretprobe_trampoline);
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 7f7636aac6209..4420499f7bb46 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -41,7 +41,7 @@ extern void _paravirt_nop(void);
asm (".pushsection .entry.text, \"ax\"\n"
".global _paravirt_nop\n"
"_paravirt_nop:\n\t"
- "ret\n\t"
+ ASM_RET
".size _paravirt_nop, . - _paravirt_nop\n\t"
".type _paravirt_nop, @function\n\t"
".popsection");
@@ -51,7 +51,7 @@ asm (".pushsection .entry.text, \"ax\"\n"
".global paravirt_ret0\n"
"paravirt_ret0:\n\t"
"xor %" _ASM_AX ", %" _ASM_AX ";\n\t"
- "ret\n\t"
+ ASM_RET
".size paravirt_ret0, . - paravirt_ret0\n\t"
".type paravirt_ret0, @function\n\t"
".popsection");
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 28b1a4e57827e..b026350c04c7f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -315,7 +315,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
__FOP_FUNC(#name)
#define __FOP_RET(name) \
- "ret \n\t" \
+ ASM_RET \
".size " name ", .-" name "\n\t"
#define FOP_RET(name) \
@@ -435,7 +435,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
__FOP_RET(#op)
asm(".pushsection .fixup, \"ax\"\n"
- "kvm_fastop_exception: xor %esi, %esi; ret\n"
+ "kvm_fastop_exception: xor %esi, %esi; " ASM_RET
".popsection");
FOP_START(setcc)
diff --git a/arch/x86/lib/error-inject.c b/arch/x86/lib/error-inject.c
index be5b5fb1598bd..520897061ee09 100644
--- a/arch/x86/lib/error-inject.c
+++ b/arch/x86/lib/error-inject.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
+#include <linux/linkage.h>
#include <linux/error-injection.h>
#include <linux/kprobes.h>
@@ -10,7 +11,7 @@ asm(
".type just_return_func, @function\n"
".globl just_return_func\n"
"just_return_func:\n"
- " ret\n"
+ ASM_RET
".size just_return_func, .-just_return_func\n"
);
diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index 690e4a9ff3330..bc8f0d6cd6f86 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -31,7 +31,7 @@ asm (
" call my_direct_func1\n"
" leave\n"
" .size my_tramp1, .-my_tramp1\n"
-" ret\n"
+ ASM_RET
" .type my_tramp2, @function\n"
" .globl my_tramp2\n"
" my_tramp2:"
@@ -39,7 +39,7 @@ asm (
" movq %rsp, %rbp\n"
" call my_direct_func2\n"
" leave\n"
-" ret\n"
+ ASM_RET
" .size my_tramp2, .-my_tramp2\n"
" .popsection\n"
);
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index 6e0de725bf221..d1bec1cded58b 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -31,7 +31,7 @@ asm (
" popq %rsi\n"
" popq %rdi\n"
" leave\n"
-" ret\n"
+ ASM_RET
" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);
diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index a30aa42ec76a8..51312e0ae2b1d 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -25,7 +25,7 @@ asm (
" call my_direct_func\n"
" popq %rdi\n"
" leave\n"
-" ret\n"
+ ASM_RET
" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);
--
GitLab