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Peter Anvin" , Peter Zijlstra , "Kirill A . Shutemov" Subject: [PATCH RESEND -tip] x86/percpu: Use %RIP-relative address in untagged_addr() Date: Wed, 13 Dec 2023 16:03:15 +0100 Message-ID: <20231213150357.5942-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" %RIP-relative addresses are nowadays correctly handled in alternative instructions, so remove misleading comment and improve assembly to use %RIP-relative address. Also, explicitly using %gs: prefix will segfault for non-SMP builds. Use macros from percpu.h which will DTRT with segment prefix register as far as SMP/non-SMP builds are concerned. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Acked-by: Peter Zijlstra (Intel) Acked-by: Kirill A. Shutemov Signed-off-by: Uros Bizjak --- arch/x86/include/asm/uaccess_64.h | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uacce= ss_64.h index f2c02e4469cc..01455c0b070c 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -11,6 +11,7 @@ #include #include #include +#include =20 #ifdef CONFIG_ADDRESS_MASKING /* @@ -18,14 +19,10 @@ */ static inline unsigned long __untagged_addr(unsigned long addr) { - /* - * Refer tlbstate_untag_mask directly to avoid RIP-relative relocation - * in alternative instructions. The relocation gets wrong when gets - * copied to the target place. - */ asm (ALTERNATIVE("", - "and %%gs:tlbstate_untag_mask, %[addr]\n\t", X86_FEATURE_LAM) - : [addr] "+r" (addr) : "m" (tlbstate_untag_mask)); + "and " __percpu_arg([mask]) ", %[addr]", X86_FEATURE_LAM) + : [addr] "+r" (addr) + : [mask] "m" (__my_cpu_var(tlbstate_untag_mask))); =20 return addr; } --=20 2.42.0