From nobody Sun Jan 4 13:21:56 2026 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4dkdPc5vYCz6N1j6 for ; Sun, 04 Jan 2026 13:21:56 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R13" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4dkdPc4BQpz3LLs for ; Sun, 04 Jan 2026 13:21:56 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1767532916; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=w8PMVRzjnfQrOqJt4GOuGVqGkrhZMWqWTd8k8jbCN+c=; b=M4MLu+CcLqtGJQuIDEs+InxV4k8FQX5pk74et5xWk4sfrA+avTBTbeinh2+dK8ouvmWVQW DzPu8QPoOp1xTzsX9XfSOPOtPeI1J+A4QOWE76F2RWol1IfaUzW/hWf7AfjdcsonF1xUH5 bBxkV2cJVC7//fb0YaEsge0iAZAoUfWsTxNEtalJodsoXg1EycagFZf9OIkJotY2NVWWNc aCnRdvhQ6bGCU4AI1k8xBx/zv8NO08xqJO/7gn5LAyzh/knsynFB5Vi35vvGXqrVr2KaU/ e95wzsHQ6alXJpXrGO6jhCneuQq4LT4XL5FwNhsywfLCj2J8CM8GXEiNjJVPjQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1767532916; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=w8PMVRzjnfQrOqJt4GOuGVqGkrhZMWqWTd8k8jbCN+c=; b=R/CS/5GYmEMRSgFHuZw2tQprOboXEBMvyOSY9VkKLKc4f2OmoOJ/rsdUa895tdQYMmeN8R b3WRI5U5/nK5yifszQ1sszQ2z2gkC2IaMMSNcWy7MdhbZOmDhCzo47Mm5MBSoQZu7BMlQ7 l90RPrgB7SUBGHKejV0W5dgL1LQXu6dbE6g8I2MIl0xkMw9Ca1Zrm7dveukQhJno3dg6ST bMR+kElEXuYPqGZilBAJFZWV/KSJnW19a61z8wZgbTznrKm2lgfT1U/fUemAEe1cCgXBPg w/OPzJoJQY26xTZyCqkgIZQgMgxlm2wFYkND7fpX2kv7upemXO+dbkkiiKsETA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1767532916; a=rsa-sha256; cv=none; b=l7r6hDCWf44lt1GI3d4JDpyRNleOKrHAYjanHd/FSRKxcj2fYBtfxf93dPzTQakNQ/GlPG N8ZMpzjDMKGz3MV9GVo5VV4B/HnEbFx1y5OxqQoG+4T7b6txJ9T24ZxxrzWYW77nbRW8Hz bCjQHFJ74fQ9BxIpiohVtQdzTvdzDj1hgBsaWd11WcOzWzCwB4x/cWhZEv9IwDSqHX0DYl tyPUqYS7CRht5yO0RH4zfbQH9p73bKLFNv62E+cg2a66gTymf4if7dPZB9/r2zCefm4hp3 EolMjjuQV7vS2Zw7fI621rjnOsZACKM2KONS4zn5By2W/4VtJ0LrIEDXnImu5A== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4dkdPc3nYNzcll for ; Sun, 04 Jan 2026 13:21:56 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 3967a by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Sun, 04 Jan 2026 13:21:56 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Robert Clausecker Subject: git: 2f83319214d9 - main - libc/amd64: fix stpncpy.S again List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: fuz X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 2f83319214d9adb8ab7a77e35d1014658b3f9cae Auto-Submitted: auto-generated Date: Sun, 04 Jan 2026 13:21:56 +0000 Message-Id: <695a6974.3967a.494e6935@gitrepo.freebsd.org> The branch main has been updated by fuz: URL: https://cgit.FreeBSD.org/src/commit/?id=2f83319214d9adb8ab7a77e35d1014658b3f9cae commit 2f83319214d9adb8ab7a77e35d1014658b3f9cae Author: Robert Clausecker AuthorDate: 2025-12-18 23:37:33 +0000 Commit: Robert Clausecker CommitDate: 2026-01-04 13:21:41 +0000 libc/amd64: fix stpncpy.S again The previous fix introduced a regression on machines without the BMI1 instruction set extension. The TZCNT instruction used in this function behaves different on old machines when the source operand is zero, but the code was originally designed to never trigger this case. The bug fix caused this case to be possible, leading to a regression on sufficiently old hardware. Fix the code by messing with things such that the source operand is never zero. PR: 291720 Fixes: 66eb78377bf109af1d9e25626bf254b4369436ec Tested by: cy Approved by: markj (mentor) Differential Revision: https://reviews.freebsd.org/D54303 --- lib/libc/amd64/string/stpncpy.S | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/lib/libc/amd64/string/stpncpy.S b/lib/libc/amd64/string/stpncpy.S index 764ee1d4008c..2efadc97a435 100644 --- a/lib/libc/amd64/string/stpncpy.S +++ b/lib/libc/amd64/string/stpncpy.S @@ -36,9 +36,7 @@ .set stpncpy, __stpncpy ARCHFUNCS(__stpncpy) ARCHFUNC(__stpncpy, scalar) -#if 0 /* temporarily disabled cf. PR 291720 */ ARCHFUNC(__stpncpy, baseline) -#endif ENDARCHFUNCS(__stpncpy) ARCHENTRY(__stpncpy, scalar) @@ -93,7 +91,6 @@ ARCHEND(__stpncpy, scalar) /* stpncpy(char *restrict rdi, const char *rsi, size_t rdx) */ ARCHENTRY(__stpncpy, baseline) #define bounce (-3*16-8) /* location of on-stack bounce buffer */ - test %rdx, %rdx # no bytes to copy? jz .L0 @@ -225,8 +222,8 @@ ARCHENTRY(__stpncpy, baseline) /* 1--32 bytes to copy, bounce through the stack */ .Lrunt: movdqa %xmm1, bounce+16(%rsp) # clear out rest of on-stack copy - bts %r10, %r8 # treat end of buffer as end of string and %r9d, %r8d # mask out head before string + bts %r10, %r8 # treat end of buffer as end of string test $0x1ffff, %r8d # end of string within first chunk or right after? jnz 0f # if yes, do not inspect second buffer @@ -235,10 +232,10 @@ ARCHENTRY(__stpncpy, baseline) pcmpeqb %xmm1, %xmm0 # NUL in second chunk? pmovmskb %xmm0, %r9d shl $16, %r9d - or %r9d, %r8d # merge found NUL bytes into NUL mask + or %r9, %r8 # merge found NUL bytes into NUL mask /* end of string after one buffer */ -0: tzcnt %r8d, %r8d # location of last char in string +0: tzcnt %r8, %r8 # location of last char in string movdqu %xmm1, bounce(%rsp, %r8, 1) # clear bytes behind string lea bounce(%rsp, %rcx, 1), %rsi # start of string copy on stack lea (%rdi, %r8, 1), %rax # return pointer to NUL byte