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Date: Sat, 27 Jan 2024 10:14:34 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
To: Xin Li <xin3.li@intel.com>, linux-kernel@vger.kernel.org
CC: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, luto@kernel.org,
        ravi.v.shankar@intel.com, andrew.cooper3@citrix.com
Subject: Re: [PATCH 1/2] x86/fred: Fix build with clang
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On January 27, 2024 1:37:27 AM PST, Xin Li <xin3=2Eli@intel=2Ecom> wrote:
>As clang doesn't allow =2Efill to refernece a symbol before it's defined,
>use asm_fred_entrypoint_user instead of asm_fred_entrypoint_kernel=2E
>
>Fixes: 5e0636a41485 ("x86/fred: FRED entry/exit and dispatch code")
>Reported-by: Borislav Petkov (AMD) <bp@alien8=2Ede>
>Link: https://lore=2Ekernel=2Eorg/lkml/20240126100050=2EGAZbOC0g3Rlr6otZc=
T@fat_crate=2Elocal/
>Signed-off-by: Xin Li <xin3=2Eli@intel=2Ecom>
>---
> arch/x86/entry/entry_64_fred=2ES | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/arch/x86/entry/entry_64_fred=2ES b/arch/x86/entry/entry_64_f=
red=2ES
>index eedf98de7538=2E=2E5427e0da190d 100644
>--- a/arch/x86/entry/entry_64_fred=2ES
>+++ b/arch/x86/entry/entry_64_fred=2ES
>@@ -43,13 +43,12 @@ SYM_INNER_LABEL(asm_fred_exit_user, SYM_L_GLOBAL)
> 	_ASM_EXTABLE_TYPE(1b, asm_fred_entrypoint_user, EX_TYPE_ERETU)
> SYM_CODE_END(asm_fred_entrypoint_user)
>=20
>-=2Efill asm_fred_entrypoint_kernel - =2E, 1, 0xcc
>-
> /*
>  * The new RIP value that FRED event delivery establishes is
>  * (IA32_FRED_CONFIG & ~FFFH) + 256 for events that occur in
>  * ring 0, i=2Ee=2E, asm_fred_entrypoint_user + 256=2E
>  */
>+	=2Efill asm_fred_entrypoint_user + 256 - =2E, 1, 0xcc
> 	=2Eorg asm_fred_entrypoint_user + 256
> SYM_CODE_START_NOALIGN(asm_fred_entrypoint_kernel)
> 	FRED_ENTER

=2Efill and =2Eorg here are redundant; in fact, there two directives mean =
exactly the same thing except that =2Eorg implicitly subtracts the current =
offset=2E