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([172.25.112.68]) by fmsmga005.fm.intel.com with ESMTP; 02 Oct 2023 23:54:50 -0700 From: Xin Li To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org, andrew.cooper3@citrix.com, jiangshanlai@gmail.com, nik.borisov@suse.com Subject: [PATCH v12 32/37] x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code Date: Mon, 2 Oct 2023 23:24:53 -0700 Message-Id: <20231003062458.23552-33-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231003062458.23552-1-xin3.li@intel.com> References: <20231003062458.23552-1-xin3.li@intel.com> 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" From: "Peter Zijlstra (Intel)" PUSH_AND_CLEAR_REGS could be used besides actual entry code; in that case %rbp shouldn't be cleared (otherwise the frame pointer is destroyed) and UNWIND_HINT shouldn't be added. Signed-off-by: Peter Zijlstra (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- arch/x86/entry/calling.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index f6907627172b..eb57c023d5df 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -65,7 +65,7 @@ For 32-bit we have the following conventions - kernel is = built with * for assembly code: */ =20 -.macro PUSH_REGS rdx=3D%rdx rcx=3D%rcx rax=3D%rax save_ret=3D0 +.macro PUSH_REGS rdx=3D%rdx rcx=3D%rcx rax=3D%rax save_ret=3D0 unwind_hint= =3D1 .if \save_ret pushq %rsi /* pt_regs->si */ movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ @@ -87,14 +87,17 @@ For 32-bit we have the following conventions - kernel i= s built with pushq %r13 /* pt_regs->r13 */ pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ + + .if \unwind_hint UNWIND_HINT_REGS + .endif =20 .if \save_ret pushq %rsi /* return address on top of stack */ .endif .endm =20 -.macro CLEAR_REGS +.macro CLEAR_REGS clear_bp=3D1 /* * Sanitize registers of values that a speculation attack might * otherwise want to exploit. The lower registers are likely clobbered @@ -109,7 +112,9 @@ For 32-bit we have the following conventions - kernel i= s built with xorl %r10d, %r10d /* nospec r10 */ xorl %r11d, %r11d /* nospec r11 */ xorl %ebx, %ebx /* nospec rbx */ + .if \clear_bp xorl %ebp, %ebp /* nospec rbp */ + .endif xorl %r12d, %r12d /* nospec r12 */ xorl %r13d, %r13d /* nospec r13 */ xorl %r14d, %r14d /* nospec r14 */ @@ -117,9 +122,9 @@ For 32-bit we have the following conventions - kernel i= s built with =20 .endm =20 -.macro PUSH_AND_CLEAR_REGS rdx=3D%rdx rcx=3D%rcx rax=3D%rax save_ret=3D0 - PUSH_REGS rdx=3D\rdx, rcx=3D\rcx, rax=3D\rax, save_ret=3D\save_ret - CLEAR_REGS +.macro PUSH_AND_CLEAR_REGS rdx=3D%rdx rcx=3D%rcx rax=3D%rax save_ret=3D0 c= lear_bp=3D1 unwind_hint=3D1 + PUSH_REGS rdx=3D\rdx, rcx=3D\rcx, rax=3D\rax, save_ret=3D\save_ret unwind= _hint=3D\unwind_hint + CLEAR_REGS clear_bp=3D\clear_bp .endm =20 .macro POP_REGS pop_rdi=3D1 --=20 2.34.1