From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id 849B63858413 for ; Thu, 5 Jan 2023 16:53:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 849B63858413 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=foss.arm.com Authentication-Results: sourceware.org; spf=none smtp.mailfrom=foss.arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0639B15BF; Thu, 5 Jan 2023 08:54:15 -0800 (PST) Received: from [10.57.45.58] (unknown [10.57.45.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 98CAA3F71A; Thu, 5 Jan 2023 08:53:32 -0800 (PST) Message-ID: <11a6c996-6575-1c62-6205-776e178cdce3@foss.arm.com> Date: Thu, 5 Jan 2023 16:53:31 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v5 8/8] newlib: libc: setjmp M-profile PACBTI-enablement Content-Language: en-GB To: "Victor L. Do Nascimento" , newlib@sourceware.org Cc: Richard Earnshaw References: From: Richard Earnshaw In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-3497.2 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,NICE_REPLY_A,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 21/12/2022 11:42, Victor L. Do Nascimento wrote: > Add function prologue/epilogue to conditionally add BTI landing pads > and/or PAC code generation & authentication instructions depending on > compilation flags. > --- > newlib/libc/machine/arm/setjmp.S | 39 ++++++++++++++++++++++++++++++++ > 1 file changed, 39 insertions(+) > > diff --git a/newlib/libc/machine/arm/setjmp.S b/newlib/libc/machine/arm/setjmp.S > index d814afea8..3e4d7cb70 100644 > --- a/newlib/libc/machine/arm/setjmp.S > +++ b/newlib/libc/machine/arm/setjmp.S > @@ -155,6 +155,8 @@ SYM (.arm_start_of.\name): > .align 2 > MODE > .globl SYM (\name) > + .fnstart > + .cfi_startproc > TYPE (\name) > SYM (\name): > PROLOGUE \name > @@ -162,6 +164,8 @@ SYM (\name): > > .macro FUNC_END name > RET > + .cfi_endproc > + .fnend > SIZE (\name) > .endm > > @@ -171,6 +175,21 @@ SYM (\name): > > FUNC_START setjmp > > +#if __ARM_FEATURE_PAC_DEFAULT > +# if __ARM_FEATURE_BTI_DEFAULT > + pacbti ip, lr, sp > +# else > + pac ip, lr, sp > +# endif /* __ARM_FEATURE_BTI_DEFAULT */ > + mov r3, ip > + str r3, [r0, #104] #104 here is a bit obscure. I think it would be clearer to write something like str r3, [r0, #(CORE_REGS_SAVE_SIZE + FP_REGS_SAVE_SIZE)] and then define these as appropriate. > + .cfi_register 143, 12 > +#else > +# if __ARM_FEATURE_BTI_DEFAULT > + bti > +# endif /* __ARM_FEATURE_BTI_DEFAULT */ > +#endif /* __ARM_FEATURE_PAC_DEFAULT */ > + > /* Save all the callee-preserved registers into the jump buffer. */ > #ifdef __thumb2__ > mov ip, sp > @@ -184,6 +203,10 @@ SYM (\name): > > /* When setting up the jump buffer return 0. */ > mov r0, #0 > +#if __ARM_FEATURE_PAC_DEFAULT > + mov ip, r3 > + aut ip, lr, sp > +#endif /* __ARM_FEATURE_PAC_DEFAULT */ > > FUNC_END setjmp > > @@ -193,6 +216,16 @@ SYM (\name): > > FUNC_START longjmp > > +#if __ARM_FEATURE_BTI_DEFAULT > + bti > +#endif /* __ARM_FEATURE_BTI_DEFAULT */ > + > +#if __ARM_FEATURE_PAC_DEFAULT > + /* Keep original jmpbuf address for retrieving pac-code > + for authentication. */ > + mov r2, r0 > +#endif /* __ARM_FEATURE_PAC_DEFAULT */ > + > /* If we have stack extension code it ought to be handled here. */ > > /* Restore the registers, retrieving the state when setjmp() was called. */ > @@ -212,5 +245,11 @@ SYM (\name): > it eq > moveq r0, #1 > > +#if __ARM_FEATURE_PAC_DEFAULT > + ldr r3, [r2, #104] > + mov ip, r3 See above. Also, you don't need to load into r3 and then move to IP, just load ip directly. > + aut ip, lr, sp > +#endif /* __ARM_FEATURE_PAC_DEFAULT */ > + > FUNC_END longjmp > #endif R.