Introduce start/end markers of __x86_indirect_thunk_* functions.
These thunk functions are placed in .text.__x86.indirect_thunk.*
sections. So this puts those sections in the end of kernel text
and adds __indirect_thunk_start/end so that other subsystem
(e.g. kprobes) can identify it.
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
arch/x86/include/asm/nospec-branch.h | 3 +++
arch/x86/kernel/vmlinux.lds.S | 35 ++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/arch/x86/include/asm/nospec-branch.h
b/arch/x86/include/asm/nospec-branch.h
index 7b45d8424150..19ba5ad19c65 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -194,6 +194,9 @@ enum spectre_v2_mitigation {
SPECTRE_V2_IBRS,
};
+extern char __indirect_thunk_start[];
+extern char __indirect_thunk_end[];
+
/*
* On VMEXIT we must ensure that no RSB predictions learned in the guest
* can be followed in the host, by overwriting the RSB completely. Both
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 1e413a9326aa..1a5a663620ce 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -74,6 +74,9 @@ jiffies_64 = jiffies;
#endif
+#define X86_INDIRECT_THUNK(reg) \
+ *(.text.__x86.indirect_thunk.##reg)
+
PHDRS {
text PT_LOAD FLAGS(5); /* R_E */
data PT_LOAD FLAGS(6); /* RW_ */
@@ -124,6 +127,38 @@ SECTIONS
ASSERT(. - _entry_trampoline == PAGE_SIZE, "entry trampoline is
too big");
#endif
+#ifdef CONFIG_RETPOLINE
+ __indirect_thunk_start = .;
+#ifdef CONFIG_X86_64
+ X86_INDIRECT_THUNK(rax)
+ X86_INDIRECT_THUNK(rbx)
+ X86_INDIRECT_THUNK(rcx)
+ X86_INDIRECT_THUNK(rdx)
+ X86_INDIRECT_THUNK(rsi)
+ X86_INDIRECT_THUNK(rdi)
+ X86_INDIRECT_THUNK(rbp)
+ X86_INDIRECT_THUNK(rsp)
+ X86_INDIRECT_THUNK(r8)
+ X86_INDIRECT_THUNK(r9)
+ X86_INDIRECT_THUNK(r10)
+ X86_INDIRECT_THUNK(r11)
+ X86_INDIRECT_THUNK(r12)
+ X86_INDIRECT_THUNK(r13)
+ X86_INDIRECT_THUNK(r14)
+ X86_INDIRECT_THUNK(r15)
+#else
+ X86_INDIRECT_THUNK(eax)
+ X86_INDIRECT_THUNK(ebx)
+ X86_INDIRECT_THUNK(ecx)
+ X86_INDIRECT_THUNK(edx)
+ X86_INDIRECT_THUNK(esi)
+ X86_INDIRECT_THUNK(edi)
+ X86_INDIRECT_THUNK(ebp)
+ X86_INDIRECT_THUNK(esp)
+#endif
+ __indirect_thunk_end = .;
+#endif
+
/* End of text section */
_etext = .;
} :text = 0x9090
