From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>,
Nick Desaulniers <ndesaulniers@google.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Subject: [PATCH 5.15 28/78] x86/retpoline: Use -mfunction-return
Date: Tue, 12 Jul 2022 20:38:58 +0200 [thread overview]
Message-ID: <20220712183239.940184256@linuxfoundation.org> (raw)
In-Reply-To: <20220712183238.844813653@linuxfoundation.org>
From: Peter Zijlstra <peterz@infradead.org>
commit 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae upstream.
Utilize -mfunction-return=thunk-extern when available to have the
compiler replace RET instructions with direct JMPs to the symbol
__x86_return_thunk. This does not affect assembler (.S) sources, only C
sources.
-mfunction-return=thunk-extern has been available since gcc 7.3 and
clang 15.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: RETPOLINE_CFLAGS is at Makefile]
[cascardo: remove ANNOTATE_NOENDBR from __x86_return_thunk]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Makefile | 2 ++
arch/x86/include/asm/nospec-branch.h | 2 ++
arch/x86/lib/retpoline.S | 12 ++++++++++++
3 files changed, 16 insertions(+)
--- a/Makefile
+++ b/Makefile
@@ -687,11 +687,13 @@ endif
ifdef CONFIG_CC_IS_GCC
RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
+RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern)
RETPOLINE_VDSO_CFLAGS := $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)
endif
ifdef CONFIG_CC_IS_CLANG
RETPOLINE_CFLAGS := -mretpoline-external-thunk
RETPOLINE_VDSO_CFLAGS := -mretpoline
+RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern)
endif
export RETPOLINE_CFLAGS
export RETPOLINE_VDSO_CFLAGS
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -120,6 +120,8 @@
_ASM_PTR " 999b\n\t" \
".popsection\n\t"
+extern void __x86_return_thunk(void);
+
#ifdef CONFIG_RETPOLINE
typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -66,3 +66,15 @@ SYM_CODE_END(__x86_indirect_thunk_array)
#define GEN(reg) EXPORT_THUNK(reg)
#include <asm/GEN-for-each-reg.h>
#undef GEN
+
+/*
+ * This function name is magical and is used by -mfunction-return=thunk-extern
+ * for the compiler to generate JMPs to it.
+ */
+SYM_CODE_START(__x86_return_thunk)
+ UNWIND_HINT_EMPTY
+ ret
+ int3
+SYM_CODE_END(__x86_return_thunk)
+
+__EXPORT_THUNK(__x86_return_thunk)
next prev parent reply other threads:[~2022-07-12 19:00 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 18:38 [PATCH 5.15 00/78] 5.15.55-rc1 review Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 01/78] x86/traps: Use pt_regs directly in fixup_bad_iret() Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 02/78] x86/entry: Switch the stack after error_entry() returns Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 03/78] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 04/78] x86/entry: Dont call error_entry() for XENPV Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 05/78] objtool: Classify symbols Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 06/78] objtool: Explicitly avoid self modifying code in .altinstr_replacement Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 07/78] objtool: Shrink struct instruction Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 08/78] objtool,x86: Replace alternatives with .retpoline_sites Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 09/78] objtool: Introduce CFI hash Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 10/78] x86/retpoline: Remove unused replacement symbols Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 11/78] x86/asm: Fix register order Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 12/78] x86/asm: Fixup odd GEN-for-each-reg.h usage Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 13/78] x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 14/78] x86/retpoline: Create a retpoline thunk array Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 15/78] x86/alternative: Implement .retpoline_sites support Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 16/78] x86/alternative: Handle Jcc __x86_indirect_thunk_\reg Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 17/78] x86/alternative: Try inline spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 18/78] x86/alternative: Add debug prints to apply_retpolines() Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 19/78] bpf,x86: Simplify computing label offsets Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 20/78] bpf,x86: Respect X86_FEATURE_RETPOLINE* Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 21/78] objtool: Default ignore INT3 for unreachable Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 22/78] x86/entry: Remove skip_r11rcx Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 23/78] x86/realmode: build with -D__DISABLE_EXPORTS Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 24/78] x86/kvm/vmx: Make noinstr clean Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 25/78] x86/cpufeatures: Move RETPOLINE flags to word 11 Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 26/78] x86/retpoline: Cleanup some #ifdefery Greg Kroah-Hartman
2022-07-12 18:38 ` [PATCH 5.15 27/78] x86/retpoline: Swizzle retpoline thunk Greg Kroah-Hartman
2022-07-12 18:38 ` Greg Kroah-Hartman [this message]
2022-07-12 18:38 ` [PATCH 5.15 29/78] x86: Undo return-thunk damage Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 30/78] x86,objtool: Create .return_sites Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 31/78] objtool: skip non-text sections when adding return-thunk sites Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 32/78] x86,static_call: Use alternative RET encoding Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 33/78] x86/ftrace: " Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 34/78] x86/bpf: " Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 35/78] x86/kvm: Fix SETcc emulation for return thunks Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 36/78] x86/vsyscall_emu/64: Dont use RET in vsyscall emulation Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 37/78] x86/sev: Avoid using __x86_return_thunk Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 38/78] x86: Use return-thunk in asm code Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 39/78] x86/entry: Avoid very early RET Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 40/78] objtool: Treat .text.__x86.* as noinstr Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 41/78] x86: Add magic AMD return-thunk Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 42/78] x86/bugs: Report AMD retbleed vulnerability Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 43/78] x86/bugs: Add AMD retbleed= boot parameter Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 44/78] x86/bugs: Enable STIBP for JMP2RET Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 45/78] x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 46/78] x86/entry: Add kernel IBRS implementation Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 47/78] x86/bugs: Optimize SPEC_CTRL MSR writes Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 48/78] x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 49/78] x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 50/78] x86/bugs: Report Intel retbleed vulnerability Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 51/78] intel_idle: Disable IBRS during long idle Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 52/78] objtool: Update Retpoline validation Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 53/78] x86/xen: Rename SYS* entry points Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 54/78] x86/xen: Add UNTRAIN_RET Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 55/78] x86/bugs: Add retbleed=ibpb Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 56/78] x86/bugs: Do IBPB fallback check only once Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 57/78] objtool: Add entry UNRET validation Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 58/78] x86/cpu/amd: Add Spectral Chicken Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 59/78] x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 60/78] x86/speculation: Fix firmware entry SPEC_CTRL handling Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 61/78] x86/speculation: Fix SPEC_CTRL write on SMT state change Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 62/78] x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 63/78] x86/speculation: Remove x86_spec_ctrl_mask Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 64/78] objtool: Re-add UNWIND_HINT_{SAVE_RESTORE} Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 65/78] KVM: VMX: Flatten __vmx_vcpu_run() Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 66/78] KVM: VMX: Convert launched argument to flags Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 67/78] KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 68/78] KVM: VMX: Fix IBRS handling after vmexit Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 69/78] x86/speculation: Fill RSB on vmexit for IBRS Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 70/78] x86/common: Stamp out the stepping madness Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 71/78] x86/cpu/amd: Enumerate BTC_NO Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 72/78] x86/retbleed: Add fine grained Kconfig knobs Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 73/78] x86/bugs: Add Cannon lake to RETBleed affected CPU list Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 74/78] x86/entry: Move PUSH_AND_CLEAR_REGS() back into error_entry Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 75/78] x86/bugs: Do not enable IBPB-on-entry when IBPB is not supported Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 76/78] x86/kexec: Disable RET on kexec Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 77/78] x86/speculation: Disable RRSBA behavior Greg Kroah-Hartman
2022-07-12 18:39 ` [PATCH 5.15 78/78] x86/static_call: Serialize __static_call_fixup() properly Greg Kroah-Hartman
2022-07-12 23:25 ` [PATCH 5.15 00/78] 5.15.55-rc1 review Florian Fainelli
2022-07-13 3:19 ` Shuah Khan
2022-07-13 3:25 ` Bagas Sanjaya
2022-07-13 7:17 ` Jon Hunter
2022-07-13 10:09 ` Sudip Mukherjee (Codethink)
2022-07-13 12:52 ` Naresh Kamboju
2022-07-13 13:34 ` Guenter Roeck
2022-07-13 18:33 ` Linus Torvalds
2022-07-13 18:40 ` Linus Torvalds
2022-07-14 9:01 ` Borislav Petkov
2022-07-14 13:46 ` Paolo Bonzini
2022-07-14 14:46 ` Boris Petkov
2022-07-14 17:02 ` Linus Torvalds
2022-07-14 17:12 ` Paolo Bonzini
2022-07-14 17:22 ` Peter Zijlstra
2022-07-14 18:00 ` Linus Torvalds
2022-07-14 18:16 ` Linus Torvalds
2022-07-14 19:26 ` Boris Petkov
2022-07-15 11:35 ` Paolo Bonzini
2022-07-14 16:51 ` Linus Torvalds
2022-07-14 17:00 ` Borislav Petkov
2022-07-14 20:39 ` Linus Torvalds
2022-07-15 14:03 ` Borislav Petkov
2022-07-14 9:50 ` Maxim Levitsky
2022-07-14 10:04 ` Greg Kroah-Hartman
2022-07-14 10:59 ` Maxim Levitsky
2022-07-13 16:41 ` Ron Economos
2022-07-13 22:18 ` Guenter Roeck
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