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AJvYcCUKKVRc56ydvT2zjay5hBpxJJZWpFbjB32xlmrOxYvHfR1n8wzrgBQtJmTSY9KCrYjdbTrVpVGm9w==@kvack.org X-Gm-Message-State: AOJu0YzNlwrH2Z2Lt2+KRRR0inoHpRnpZsi+bZJqG2GivYzVqgRRnhTc EctkufvlAil9dnR3LdTIfkFan4UVRRKNXxzBs+Yd82R+nPH2bY5GlldaojdC5Zy+n0xpWrvQR7h c0BvJ8Ei63w8YHCSDdSHMz/MaBRIlSQ== X-Gm-Gg: ASbGnct+nyyzLsgY1AK6Q6qUsBxnVn6XvurMIzcAs09oqtQonlxewZyN4pY3lkHXqgv E83Nz1Hu9C2ViGZcGd7IfQkDHM7FQaRUOTAdTfkdKT98PbD9NWe9w+jKT0pwT6WmszziKUlu+Ho /droAwXKghh3Z6gg3h/AQWMpbjLVrBPZGPOVwIXFwC15Q6JrH01u7FyL+QPJuvfUY5poemLoXUr mbGSfDiv/fI2id2f1zTJeJ0ki5IYBurvnher6ytgZ7dgUClmL4I4vZX7o19bDUW+BbqdAV895k= X-Google-Smtp-Source: AGHT+IGEuL5EZ1//R48jmqcfeWhsVo1m8oxthAF3NZBoYhNUuWGZKmZifPFDiAMnhMvwmoelT2mK6IbqIEbGCeJQ3WQ= X-Received: by 2002:a05:6512:6c9:b0:57a:311:3234 with SMTP id 2adb3069b0e04-594128e9881mr684224e87.55.1761720895815; Tue, 28 Oct 2025 23:54:55 -0700 (PDT) MIME-Version: 1.0 References: <20251026221208.1938173-1-hpa@zytor.com> <20251026221208.1938173-4-hpa@zytor.com> In-Reply-To: <20251026221208.1938173-4-hpa@zytor.com> From: Brian Gerst Date: Wed, 29 Oct 2025 02:54:43 -0400 X-Gm-Features: AWmQ_bmfiyfREKo0e-gaQFIywqypW-gaTtMVt4rv1DnveKwp_KlVvqDZ1gAvjyk Message-ID: Subject: Re: [PATCH 3/6] x86/entry/vdso32: remove int80_landing_pad To: "H. Peter Anvin" Cc: "Jason A. Donenfeld" , "Peter Zijlstra (Intel)" , "Theodore Ts'o" , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= , Xin Li , Andrew Cooper , Andy Lutomirski , Ard Biesheuvel , Borislav Petkov , Dave Hansen , Ingo Molnar , James Morse , Jarkko Sakkinen , Josh Poimboeuf , Kees Cook , Nam Cao , Oleg Nesterov , Perry Yuan , Thomas Gleixner , Thomas Huth , Uros Bizjak , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-sgx@vger.kernel.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam05 X-Stat-Signature: jjn8m57tsbohq8jbwkhht1urcwnch1qz X-Rspam-User: X-Rspamd-Queue-Id: 0C1E74000A X-HE-Tag: 1761720897-368879 X-HE-Meta: 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 y0zPK+Cx V5MD9hHaNNVNe87Gye3GHc6aw6GhDaE/ZCc7K4yNXCVvXg2Ae+vjuB2taVrcS21oxyzVT5onH1K4y1D69VVV41YWIjZZ1A1aCDkBDpIvi3DcBXzfVyRLwHc5Z6FzuAWSbPPX0WPvRI0c1nnQ5uzcYZMCXYEmkHGotIKzwogGCZpgCjAiWggAKel73vB95gEZJS/0w95v4Xdbx/wYC900K5F8+tHWNQNfqknDR0dMO459fN7UoH/9D9wBdshpNRnQ4eh/9CitkyWcgp1+Tyd/Xd+s1K3Jx+Kaw28/lyu3s4B7Fj4y4JQbcSdONWlfJ8bT0+khcporD4/3Wc9tPPC3Fn5foog8b3lyZ4Si8Hp46N60hgrVcAjmMmR5MQLtFJiPVtJllR0s/b0U+kdd8EBezu3dhYZMGt2NySH+iPuwEj18b7XT2fY20zTNZTYGWcOwVk/PQC655AlPmLqBJDuiF4dBnkg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Oct 26, 2025 at 6:12=E2=80=AFPM H. Peter Anvin wrot= e: > > There is no fundamental reason for the int80_landing_pad symbol. If ip > falls within the vdso, and the vdso is moved, we should change the ip > accordingly, regardless of mode or location within the vdso. This > *currently* can only happen on 32 bits, but there isn't any reason not > to do so generically. > > Note that if this is ever possible from a vdso-internal call, then the > user space stack will also needed to be adjusted (as well as the > shadow stack, if enabled.) Fortunately this is not currently the case. > > At the moment, we don't even consider other threads when moving the > vdso. The assumption is that it is only used by process freeze/thaw > for migration, where this is not an issue. > > Signed-off-by: H. Peter Anvin (Intel) > --- > arch/x86/entry/vdso/vdso32/system_call.S | 1 - > arch/x86/entry/vdso/vma.c | 16 ++++++---------- > arch/x86/tools/vdso2c.c | 1 - > 3 files changed, 6 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vd= so/vdso32/system_call.S > index 2a15634bbe75..d14eca4403c5 100644 > --- a/arch/x86/entry/vdso/vdso32/system_call.S > +++ b/arch/x86/entry/vdso/vdso32/system_call.S > @@ -62,7 +62,6 @@ __kernel_vsyscall: > > /* Enter using int $0x80 */ > int $0x80 > -SYM_INNER_LABEL(int80_landing_pad, SYM_L_GLOBAL) This is still needed by do_fast_syscall_32(). Brian Gerst