Date: Wed, 26 May 2021 19:29:10 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 4590f0345956 - stable/12 - amd64: clear PSL.AC in the right frame Message-ID: <202105261929.14QJTAZ4059713@gitrepo.freebsd.org>
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The branch stable/12 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=4590f0345956329d414611c6cee300f486732b53 commit 4590f0345956329d414611c6cee300f486732b53 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-05-22 19:48:36 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-05-26 19:29:06 +0000 amd64: clear PSL.AC in the right frame If copyin family of routines fault, kernel does clear PSL.AC on the fault entry, but the AC flag of the faulted frame is kept intact. Since onfault handler is effectively jump, AC survives until syscall exit. Reported by: m00nbsd, via Sony Reviewed by: markj Sponsored by: The FreeBSD Foundation admbugs: 975 (cherry picked from commit 91aae953cb807d6fb7a70782b323bf9beb60d7c9) --- sys/amd64/amd64/support.S | 18 ++++++++++++------ sys/amd64/linux/linux_support.s | 5 ++++- sys/amd64/linux32/linux32_support.s | 5 ++++- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S index 58bf5f7303ec..906e52b81db7 100644 --- a/sys/amd64/amd64/support.S +++ b/sys/amd64/amd64/support.S @@ -868,9 +868,11 @@ ENTRY(copyin_smap_erms) END(copyin_smap_erms) ALIGN_TEXT - /* Trap entry clears PSL.AC */ copy_fault: - movq $0,PCB_ONFAULT(%r11) + testl $CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip) + je 1f + clac +1: movq $0,PCB_ONFAULT(%r11) movl $EFAULT,%eax POP_FRAME_POINTER ret @@ -1311,9 +1313,11 @@ ENTRY(subyte_smap) END(subyte_smap) ALIGN_TEXT - /* Fault entry clears PSL.AC */ fusufault: - movq PCPU(CURPCB),%rcx + testl $CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip) + je 1f + clac +1: movq PCPU(CURPCB),%rcx xorl %eax,%eax movq %rax,PCB_ONFAULT(%rcx) decq %rax @@ -1396,8 +1400,10 @@ ENTRY(copyinstr_smap) END(copyinstr_smap) cpystrflt: - /* Fault entry clears PSL.AC */ - movl $EFAULT,%eax + testl $CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip) + je 1f + clac +1: movl $EFAULT,%eax cpystrflt_x: /* set *lencopied and return %eax */ movq $0,PCB_ONFAULT(%r9) diff --git a/sys/amd64/linux/linux_support.s b/sys/amd64/linux/linux_support.s index 45eb565f667d..bb1c218bdf89 100644 --- a/sys/amd64/linux/linux_support.s +++ b/sys/amd64/linux/linux_support.s @@ -34,7 +34,10 @@ #include "assym.inc" futex_fault: - movq $0,PCB_ONFAULT(%r8) + testl $CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip) + je 1f + clac +1: movq $0,PCB_ONFAULT(%r8) movl $-EFAULT,%eax ret diff --git a/sys/amd64/linux32/linux32_support.s b/sys/amd64/linux32/linux32_support.s index da076010c13c..86f3d11b552b 100644 --- a/sys/amd64/linux32/linux32_support.s +++ b/sys/amd64/linux32/linux32_support.s @@ -34,7 +34,10 @@ #include "assym.inc" futex_fault: - movq $0,PCB_ONFAULT(%r8) + testl $CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip) + je 1f + clac +1: movq $0,PCB_ONFAULT(%r8) movl $-EFAULT,%eax ret
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