From nobody Sun Jan 4 13:24:01 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 4dkdS23lt6z6N22R for ; Sun, 04 Jan 2026 13:24:02 +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 4dkdS203wDz3Mmb for ; Sun, 04 Jan 2026 13:24:02 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1767533042; 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=39TIpkZj7PwQxjLTahalkjo4mHFvhKS/yE4dlQBzus4=; b=ATP3dknSKxpMwBMuqUg1wU9icGRslkYC5YEzGb44R/8rx3S663cEXs9VR/pm7LhRyHH6Cb C/JF3315Lo0McPunLxzja8apUKW8yKZcDDgEYHsWzvzuNc5hKU/JUJ0E2HgEdlmZ55jYik +HVFfeH4YXqwujVBGK1u7BSFTsYCjimm3sFSINy33LKbEilwxJCgSre6v5jJLTuowQiVBi NfXJIoydOnSrH4L3Xll9Kw4UeJdCL+75E+PCYMfl6ku5t1JVcJ8fEjSSepc223GvIV0D8w btJdi+AyGSvq1enXu+g9QxeffEKvwjt8Hs3UoV4u5eod0VLD6zlsGhAINbingw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1767533042; 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=39TIpkZj7PwQxjLTahalkjo4mHFvhKS/yE4dlQBzus4=; b=Vqmpff2GfVnXcQExAE5X7t9OD6aAlZJ2NNSByJMdycG3igp0Krk0QTRiATNLzSe1lt45Y0 78yFnmkH9bhARHSM+ArpFtjYn5bskrHNRD6/BQ/0if56K2G2wasESAJYh3IWXFxnfO5f+C QLVv7uumXwWy9cvrlD9qd6YJpN+jOSpIBX5bzCbk0hbR6v+lkOtHPXHfT/xJVUP3eNLN27 aTVGSf5AB6a5kO5uvEv0eouyE7Kzgk7fehyBU/eTxFUCjlloxeMC19/d/nzaU8LlP6QwZC orFJQfSXxERUAxwsUEFXauRikdqKJyVgDzjjTnUyx+emKvnEJQFDzxq2cXyfIg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1767533042; a=rsa-sha256; cv=none; b=eMfXyqg3ZWEsNXUdpP4yoMlycxU39vmTkfS3UITTt1oJKUXUTPbOVrEDmnQh95hpHAYr0p emJnORM1KSHfE15VMIBtPK/aV+d15KZzEjT80X27iY8KSE+MjZ7fBjGuqnmqXY7KK+zRbG CTJF5agmmNIt8OLx9VR1s8m0ajU0MyfQqHW9/sSmoOPuFpaKvRpGYJkhs1MvEwTK9uCsT2 ctEsY4yI8sFw59cotY+80kcLLOdlf+ajpsuBhydxDigWIw2m56PX2zuJbkSBDKFL9OCJpP 0DLW4H8o3nSLVDU9niwceYauoT7EzrN1J7SupNWSynx3+iBmH8yVMdO/HjALeg== 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 4dkdS166m1zd1C for ; Sun, 04 Jan 2026 13:24:01 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 39da1 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Sun, 04 Jan 2026 13:24:01 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Robert Clausecker Subject: git: 9c68745a5064 - stable/15 - 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/stable/15 X-Git-Reftype: branch X-Git-Commit: 9c68745a50640ccff37565e3cbfe53dddc18d7d3 Auto-Submitted: auto-generated Date: Sun, 04 Jan 2026 13:24:01 +0000 Message-Id: <695a69f1.39da1.5b9f90d9@gitrepo.freebsd.org> The branch stable/15 has been updated by fuz: URL: https://cgit.FreeBSD.org/src/commit/?id=9c68745a50640ccff37565e3cbfe53dddc18d7d3 commit 9c68745a50640ccff37565e3cbfe53dddc18d7d3 Author: Robert Clausecker AuthorDate: 2025-12-18 23:37:33 +0000 Commit: Robert Clausecker CommitDate: 2026-01-04 13:22:51 +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 (cherry picked from commit 2f83319214d9adb8ab7a77e35d1014658b3f9cae) --- 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