Re: Back porting to GCC11/GCC12: Re: [patch][gcc13][i386][pr101891]Adjust -fzero-call-used-regs to always use XOR
Pushed to both gcc11 and gcc12. thanks. Qing > On May 24, 2022, at 1:19 AM, Richard Biener wrote: > > On Mon, 23 May 2022, Qing Zhao wrote: > >> Hi, >> >> I have added the patch to GCC11 and GCC12 in my local area and bootstrapped >> and regress tested on both x86 and aarch64, no any issues. >> >> Can I committed them to both GCC11 and GCC12 branches? > > Yes. > > Thanks, > Richard. > >> Thanks. >> >> >> >> >>> On May 10, 2022, at 8:38 AM, Qing Zhao via Gcc-patches >>> wrote: >>> >>> >>> On May 10, 2022, at 1:12 AM, Richard Biener wrote: On Mon, 9 May 2022, Uros Bizjak wrote: > On Mon, May 9, 2022 at 5:44 PM Qing Zhao wrote: >> >> Another question: >> >> I think that this patch might need to be back ported to Gcc12 and GCC11. >> >> What?s your opinion on this? > > It is not a regression, so following general rules, the patch should > not be backported. OTOH, the patch creates functionally equivalent > code, better in some security aspects. The functionality is also > hidden behind some non-default flag, so I think if release managers > (CC'd) are OK with the backport, I'd give it a technical approval. > >> If so, when can I backport it? > > Let's keep it in the mainline for a week or two, before backporting it > to non-EoL branches. OK from my POV after a week or two on trunk. >>> >>> Sure, I will do the back porting after two weeks. >>> >>> thanks. >>> >>> Qing Richard. > Uros. > >> >> thanks. >> >> Qing >> >>> On May 7, 2022, at 4:06 AM, Uros Bizjak wrote: >>> >>> On Fri, May 6, 2022 at 6:42 PM Qing Zhao wrote: > On May 6, 2022, at 10:58 AM, Uros Bizjak wrote: > > On Fri, May 6, 2022 at 4:29 PM Qing Zhao wrote: >> >> Hi, >> >> As Kee?s requested in this PR: >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101891 >> >> = >> >> Currently -fzero-call-used-regs will use a pattern of: >> >> XOR regA,regA >> MOV regA,regB >> MOV regA,regC >> ... >> RET >> >> However, this introduces both a register ordering dependency (e.g. >> the CPU cannot clear regB without clearing regA first), and while >> greatly reduces available ROP gadgets, it does technically leave a >> set of "MOV" ROP gadgets at the end of functions (e.g. "MOV >> regA,regC; RET"). >> >> Please switch to always using XOR: >> >> XOR regA,regA >> XOR regB,regB >> XOR regC,regC >> ... >> RET >> >> === >> >> This patch switch all MOV to XOR on i386. >> >> Bootstrapped and regresstion tested on x86_64-linux-gnu. >> >> Okay for gcc13? >> >> Thanks. >> >> Qing >> >> == > >> gcc/ChangeLog: >> >> * config/i386/i386.cc (zero_all_mm_registers): Use SET to zero >> instead >> of MOV for zeroing scratch registers. >> (ix86_zero_call_used_regs): Likewise. >> >> gcc/testsuite/ChangeLog: >> >> * gcc.target/i386/zero-scratch-regs-1.c: Add -fno-stack-protector >> -fno-PIC. >> * gcc.target/i386/zero-scratch-regs-10.c: Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-13.c: Add -msse. >> * gcc.target/i386/zero-scratch-regs-14.c: Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-15.c: Add -fno-stack-protector >> -fno-PIC. >> * gcc.target/i386/zero-scratch-regs-16.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-17.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-18.c: Add -fno-stack-protector >> -fno-PIC, adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-19.c: Add -fno-stack-protector >> -fno-PIC. >> * gcc.target/i386/zero-scratch-regs-2.c: Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-20.c: Add -msse. >> * gcc.target/i386/zero-scratch-regs-21.c: Add -fno-stack-protector >> -fno-PIC, Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-22.c: Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-23.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-26.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-27.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-28.c: Likewise. >> * gcc.target/i386/zero-scratch-regs-3.c: Add -fno-stack-protector. >> * gcc.target/i386/zero-scratch-regs-31.c: Adjust mov to xor. >> * gcc.target/i386/zero-scratch-regs-4.c: Add -fno-stack-protector >>
Re: Back porting to GCC11/GCC12: Re: [patch][gcc13][i386][pr101891]Adjust -fzero-call-used-regs to always use XOR
On Mon, 23 May 2022, Qing Zhao wrote: > Hi, > > I have added the patch to GCC11 and GCC12 in my local area and bootstrapped > and regress tested on both x86 and aarch64, no any issues. > > Can I committed them to both GCC11 and GCC12 branches? Yes. Thanks, Richard. > Thanks. > > > > > > On May 10, 2022, at 8:38 AM, Qing Zhao via Gcc-patches > > wrote: > > > > > > > >> On May 10, 2022, at 1:12 AM, Richard Biener wrote: > >> > >> On Mon, 9 May 2022, Uros Bizjak wrote: > >> > >>> On Mon, May 9, 2022 at 5:44 PM Qing Zhao wrote: > > Another question: > > I think that this patch might need to be back ported to Gcc12 and GCC11. > > What?s your opinion on this? > >>> > >>> It is not a regression, so following general rules, the patch should > >>> not be backported. OTOH, the patch creates functionally equivalent > >>> code, better in some security aspects. The functionality is also > >>> hidden behind some non-default flag, so I think if release managers > >>> (CC'd) are OK with the backport, I'd give it a technical approval. > >>> > If so, when can I backport it? > >>> > >>> Let's keep it in the mainline for a week or two, before backporting it > >>> to non-EoL branches. > >> > >> OK from my POV after a week or two on trunk. > > > > Sure, I will do the back porting after two weeks. > > > > thanks. > > > > Qing > >> > >> Richard. > >> > >>> Uros. > >>> > > thanks. > > Qing > > > On May 7, 2022, at 4:06 AM, Uros Bizjak wrote: > > > > On Fri, May 6, 2022 at 6:42 PM Qing Zhao wrote: > >> > >> > >> > >>> On May 6, 2022, at 10:58 AM, Uros Bizjak wrote: > >>> > >>> On Fri, May 6, 2022 at 4:29 PM Qing Zhao wrote: > > Hi, > > As Kee?s requested in this PR: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101891 > > = > > Currently -fzero-call-used-regs will use a pattern of: > > XOR regA,regA > MOV regA,regB > MOV regA,regC > ... > RET > > However, this introduces both a register ordering dependency (e.g. > the CPU cannot clear regB without clearing regA first), and while > greatly reduces available ROP gadgets, it does technically leave a > set of "MOV" ROP gadgets at the end of functions (e.g. "MOV > regA,regC; RET"). > > Please switch to always using XOR: > > XOR regA,regA > XOR regB,regB > XOR regC,regC > ... > RET > > === > > This patch switch all MOV to XOR on i386. > > Bootstrapped and regresstion tested on x86_64-linux-gnu. > > Okay for gcc13? > > Thanks. > > Qing > > == > >>> > gcc/ChangeLog: > > * config/i386/i386.cc (zero_all_mm_registers): Use SET to zero > instead > of MOV for zeroing scratch registers. > (ix86_zero_call_used_regs): Likewise. > > gcc/testsuite/ChangeLog: > > * gcc.target/i386/zero-scratch-regs-1.c: Add -fno-stack-protector > -fno-PIC. > * gcc.target/i386/zero-scratch-regs-10.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-13.c: Add -msse. > * gcc.target/i386/zero-scratch-regs-14.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-15.c: Add -fno-stack-protector > -fno-PIC. > * gcc.target/i386/zero-scratch-regs-16.c: Likewise. > * gcc.target/i386/zero-scratch-regs-17.c: Likewise. > * gcc.target/i386/zero-scratch-regs-18.c: Add -fno-stack-protector > -fno-PIC, adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-19.c: Add -fno-stack-protector > -fno-PIC. > * gcc.target/i386/zero-scratch-regs-2.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-20.c: Add -msse. > * gcc.target/i386/zero-scratch-regs-21.c: Add -fno-stack-protector > -fno-PIC, Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-22.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-23.c: Likewise. > * gcc.target/i386/zero-scratch-regs-26.c: Likewise. > * gcc.target/i386/zero-scratch-regs-27.c: Likewise. > * gcc.target/i386/zero-scratch-regs-28.c: Likewise. > * gcc.target/i386/zero-scratch-regs-3.c: Add -fno-stack-protector. > * gcc.target/i386/zero-scratch-regs-31.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-4.c: Add -fno-stack-protector > -fno-PIC. > * gcc.target/i386/zero-scratch-regs-5.c: Adjust mov to xor. > * gcc.target/i386/zero-scratch-regs-6.c: Add -fno-stack-protector. > *
Back porting to GCC11/GCC12: Re: [patch][gcc13][i386][pr101891]Adjust -fzero-call-used-regs to always use XOR
Hi, I have added the patch to GCC11 and GCC12 in my local area and bootstrapped and regress tested on both x86 and aarch64, no any issues. Can I committed them to both GCC11 and GCC12 branches? Thanks. > On May 10, 2022, at 8:38 AM, Qing Zhao via Gcc-patches > wrote: > > > >> On May 10, 2022, at 1:12 AM, Richard Biener wrote: >> >> On Mon, 9 May 2022, Uros Bizjak wrote: >> >>> On Mon, May 9, 2022 at 5:44 PM Qing Zhao wrote: Another question: I think that this patch might need to be back ported to Gcc12 and GCC11. What?s your opinion on this? >>> >>> It is not a regression, so following general rules, the patch should >>> not be backported. OTOH, the patch creates functionally equivalent >>> code, better in some security aspects. The functionality is also >>> hidden behind some non-default flag, so I think if release managers >>> (CC'd) are OK with the backport, I'd give it a technical approval. >>> If so, when can I backport it? >>> >>> Let's keep it in the mainline for a week or two, before backporting it >>> to non-EoL branches. >> >> OK from my POV after a week or two on trunk. > > Sure, I will do the back porting after two weeks. > > thanks. > > Qing >> >> Richard. >> >>> Uros. >>> thanks. Qing > On May 7, 2022, at 4:06 AM, Uros Bizjak wrote: > > On Fri, May 6, 2022 at 6:42 PM Qing Zhao wrote: >> >> >> >>> On May 6, 2022, at 10:58 AM, Uros Bizjak wrote: >>> >>> On Fri, May 6, 2022 at 4:29 PM Qing Zhao wrote: Hi, As Kee?s requested in this PR: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101891 = Currently -fzero-call-used-regs will use a pattern of: XOR regA,regA MOV regA,regB MOV regA,regC ... RET However, this introduces both a register ordering dependency (e.g. the CPU cannot clear regB without clearing regA first), and while greatly reduces available ROP gadgets, it does technically leave a set of "MOV" ROP gadgets at the end of functions (e.g. "MOV regA,regC; RET"). Please switch to always using XOR: XOR regA,regA XOR regB,regB XOR regC,regC ... RET === This patch switch all MOV to XOR on i386. Bootstrapped and regresstion tested on x86_64-linux-gnu. Okay for gcc13? Thanks. Qing == >>> gcc/ChangeLog: * config/i386/i386.cc (zero_all_mm_registers): Use SET to zero instead of MOV for zeroing scratch registers. (ix86_zero_call_used_regs): Likewise. gcc/testsuite/ChangeLog: * gcc.target/i386/zero-scratch-regs-1.c: Add -fno-stack-protector -fno-PIC. * gcc.target/i386/zero-scratch-regs-10.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-13.c: Add -msse. * gcc.target/i386/zero-scratch-regs-14.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-15.c: Add -fno-stack-protector -fno-PIC. * gcc.target/i386/zero-scratch-regs-16.c: Likewise. * gcc.target/i386/zero-scratch-regs-17.c: Likewise. * gcc.target/i386/zero-scratch-regs-18.c: Add -fno-stack-protector -fno-PIC, adjust mov to xor. * gcc.target/i386/zero-scratch-regs-19.c: Add -fno-stack-protector -fno-PIC. * gcc.target/i386/zero-scratch-regs-2.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-20.c: Add -msse. * gcc.target/i386/zero-scratch-regs-21.c: Add -fno-stack-protector -fno-PIC, Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-22.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-23.c: Likewise. * gcc.target/i386/zero-scratch-regs-26.c: Likewise. * gcc.target/i386/zero-scratch-regs-27.c: Likewise. * gcc.target/i386/zero-scratch-regs-28.c: Likewise. * gcc.target/i386/zero-scratch-regs-3.c: Add -fno-stack-protector. * gcc.target/i386/zero-scratch-regs-31.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-4.c: Add -fno-stack-protector -fno-PIC. * gcc.target/i386/zero-scratch-regs-5.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-6.c: Add -fno-stack-protector. * gcc.target/i386/zero-scratch-regs-7.c: Likewise. * gcc.target/i386/zero-scratch-regs-8.c: Adjust mov to xor. * gcc.target/i386/zero-scratch-regs-9.c: Add -fno-stack-protector. >>> >>> Please use something like the attached (functionally equivalent) patch >>> for the last hunk of your patch. >> >> Sure, I will update the code. >>> >>>
