linux-kernel - [PATCH v2 02/17] vdso: Clean header inclusion in getrandom

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Message-ID: <2a081f1fff5e40f496153f8e0162fc7ec5adab2e.1724309198.git.christophe.leroy@csgroup.eu>
Date: Thu, 22 Aug 2024 09:13:10 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	"Theodore Ts'o" <tytso@....edu>,
	"Jason A. Donenfeld" <Jason@...c4.com>,
	Arnd Bergmann <arnd@...db.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	Shuah Khan <shuah@...nel.org>
Cc: linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-arch@...r.kernel.org,
	linux-mm@...ck.org,
	linux-trace-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: [PATCH v2 02/17] vdso: Clean header inclusion in getrandom

Building a VDSO32 on a 64 bits kernel is problematic when some
system headers are included. See commit 8c59ab839f52 ("lib/vdso:
Enable common headers") for more details.

Minimise the amount of headers by moving needed items into
dedicated common headers.

For PAGE_SIZE and PAGE_MASK, redefine them from CONFIG_PAGE_SHIFT
in the same way as commit cffaefd15a8f ("vdso: Use CONFIG_PAGE_SHIFT
in vdso/datapage.h")

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/x86/include/asm/pvclock.h |  1 +
 include/vdso/helpers.h         |  1 +
 lib/vdso/getrandom.c           | 15 ++++++++-------
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 0c92db84469d..6e4f8fae3ce9 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -5,6 +5,7 @@
 #include <asm/clocksource.h>
 #include <asm/pvclock-abi.h>
 
+struct timespec64;
 /* some helper functions for xen and kvm pv clock sources */
 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
 u64 pvclock_clocksource_read_nowd(struct pvclock_vcpu_time_info *src);
diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
index 73501149439d..3ddb03bb05cb 100644
--- a/include/vdso/helpers.h
+++ b/include/vdso/helpers.h
@@ -4,6 +4,7 @@
 
 #ifndef __ASSEMBLY__
 
+#include <asm/barrier.h>
 #include <vdso/datapage.h>
 
 static __always_inline u32 vdso_read_begin(const struct vdso_data *vd)
diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c
index b230f0b10832..cab153c5f9be 100644
--- a/lib/vdso/getrandom.c
+++ b/lib/vdso/getrandom.c
@@ -3,15 +3,13 @@
  * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@...c4.com>. All Rights Reserved.
  */
 
-#include <linux/cache.h>
-#include <linux/kernel.h>
-#include <linux/time64.h>
+#include <linux/minmax.h>
 #include <vdso/datapage.h>
 #include <vdso/getrandom.h>
+#include <vdso/unaligned.h>
 #include <asm/vdso/getrandom.h>
-#include <asm/vdso/vsyscall.h>
-#include <asm/unaligned.h>
 #include <uapi/linux/mman.h>
+#include <uapi/linux/random.h>
 
 #define MEMCPY_AND_ZERO_SRC(type, dst, src, len) do {				\
 	while (len >= sizeof(type)) {						\
@@ -23,6 +21,9 @@
 	}									\
 } while (0)
 
+#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT)
+#define _PAGE_MASK (~(_PAGE_SIZE - 1))
+
 static void memcpy_and_zero_src(void *dst, void *src, size_t len)
 {
 	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
@@ -64,7 +65,7 @@ static __always_inline ssize_t
 __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_t len,
 		       unsigned int flags, void *opaque_state, size_t opaque_len)
 {
-	ssize_t ret = min_t(size_t, INT_MAX & PAGE_MASK /* = MAX_RW_COUNT */, len);
+	ssize_t ret = min_t(size_t, INT_MAX & _PAGE_MASK /* = MAX_RW_COUNT */, len);
 	struct vgetrandom_state *state = opaque_state;
 	size_t batch_len, nblocks, orig_len = len;
 	bool in_use, have_retried = false;
@@ -82,7 +83,7 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_
 	}
 
 	/* The state must not straddle a page, since pages can be zeroed at any time. */
-	if (unlikely(((unsigned long)opaque_state & ~PAGE_MASK) + sizeof(*state) > PAGE_SIZE))
+	if (unlikely(((unsigned long)opaque_state & ~_PAGE_MASK) + sizeof(*state) > _PAGE_SIZE))
 		return -EFAULT;
 
 	/* If the caller passes the wrong size, which might happen due to CRIU, fallback. */
-- 
2.44.0