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Message-Id: <20241216-vdso-store-rng-v1-5-f7aed1bdb3b2@linutronix.de>
Date: Mon, 16 Dec 2024 15:10:01 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>, Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Anna-Maria Behnsen <anna-maria@...utronix.de>,
Frederic Weisbecker <frederic@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
Theodore Ts'o <tytso@....edu>, "Jason A. Donenfeld" <Jason@...c4.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>,
Russell King <linux@...linux.org.uk>, Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Naveen N Rao <naveen@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>,
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>, Arnd Bergmann <arnd@...db.de>
Cc: linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-riscv@...ts.infradead.org,
loongarch@...ts.linux.dev, linux-s390@...r.kernel.org,
linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-arch@...r.kernel.org, Nam Cao <namcao@...utronix.de>,
Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH 05/17] vdso: Add generic architecture-specific data storage
Some architectures need to architecture-specific data to the vDSO.
Enable the generic vDSO storage mechanism to both store and map this
data. Some architectures require more than a single page, like
LoongArch, so prepare for that usecase, too.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
arch/Kconfig | 4 ++++
include/vdso/datapage.h | 32 ++++++++++++++++++++++++++++++++
lib/vdso_kernel/datastore.c | 14 ++++++++++++++
3 files changed, 50 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index 6682b2a53e342cbacc05b70ef99cb1c47efe55e8..48f37e6c00674f433a0d6e6e05ce72c27cf000b7 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1576,6 +1576,10 @@ config HAVE_SPARSE_SYSCALL_NR
entries at 4000, 5000 and 6000 locations. This option turns on syscall
related optimizations for a given architecture.
+config ARCH_HAS_VDSO_ARCH_DATA
+ depends on GENERIC_VDSO_DATA_STORE
+ bool
+
config ARCH_HAS_VDSO_TIME_DATA
bool
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 5ce322422fcb7ba77aeafddbf132fd3e5dbc5a0c..b3227f1cf62895aa60ce0ca96afa42259f4771f9 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -9,11 +9,13 @@
#include <uapi/linux/types.h>
#include <uapi/asm-generic/errno-base.h>
+#include <vdso/align.h>
#include <vdso/bits.h>
#include <vdso/clocksource.h>
#include <vdso/ktime.h>
#include <vdso/limits.h>
#include <vdso/math64.h>
+#include <vdso/page.h>
#include <vdso/processor.h>
#include <vdso/time.h>
#include <vdso/time32.h>
@@ -25,6 +27,15 @@
struct arch_vdso_time_data {};
#endif
+#if defined(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)
+#include <asm/vdso/arch_data.h>
+#elif defined(CONFIG_GENERIC_VDSO_DATA_STORE)
+struct vdso_arch_data {
+ /* Needed for the generic code, never actually used at runtime */
+ char __unused;
+};
+#endif
+
#define VDSO_BASES (CLOCK_TAI + 1)
#define VDSO_HRES (BIT(CLOCK_REALTIME) | \
BIT(CLOCK_MONOTONIC) | \
@@ -146,9 +157,11 @@ extern struct vdso_rng_data _vdso_rng_data __attribute__((visibility("hidden")))
extern const struct vdso_time_data vdso_u_time_data[CS_BASES] __attribute__((visibility("hidden")));
extern const struct vdso_time_data vdso_u_timens_data[CS_BASES] __attribute__((visibility("hidden")));
extern const struct vdso_rng_data vdso_u_rng_data __attribute__((visibility("hidden")));
+extern const struct vdso_arch_data vdso_u_arch_data __attribute__((visibility("hidden")));
extern struct vdso_time_data *vdso_k_time_data;
extern struct vdso_rng_data *vdso_k_rng_data;
+extern struct vdso_arch_data *vdso_k_arch_data;
#endif
/**
@@ -161,10 +174,15 @@ union vdso_data_store {
#ifdef CONFIG_GENERIC_VDSO_DATA_STORE
+#define VDSO_ARCH_DATA_SIZE ALIGN(sizeof(struct vdso_arch_data), PAGE_SIZE)
+#define VDSO_ARCH_DATA_PAGES (VDSO_ARCH_DATA_SIZE >> PAGE_SHIFT)
+
enum vdso_pages {
VDSO_TIME_PAGE_OFFSET,
VDSO_TIMENS_PAGE_OFFSET,
VDSO_RNG_PAGE_OFFSET,
+ VDSO_ARCH_PAGES_START,
+ VDSO_ARCH_PAGES_END = VDSO_ARCH_PAGES_START + VDSO_ARCH_DATA_PAGES - 1,
VDSO_NR_PAGES
};
@@ -204,6 +222,13 @@ static __always_inline struct vdso_rng_data *__arch_get_vdso_k_rng_data(void)
#endif /* CONFIG_GENERIC_VDSO_DATA_STORE */
+#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
+static __always_inline const struct vdso_arch_data *__arch_get_vdso_u_arch_data(void)
+{
+ return &vdso_u_arch_data;
+}
+#endif /* CONFIG_ARCH_HAS_VDSO_ARCH_DATA */
+
/*
* The generic vDSO implementation requires that gettimeofday.h
* provides:
@@ -234,11 +259,18 @@ static __always_inline struct vdso_rng_data *__arch_get_vdso_k_rng_data(void)
#define __vdso_u_rng_data
#endif
+#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
+#define __vdso_u_arch_data PROVIDE(vdso_u_arch_data = vdso_u_data + 3 * PAGE_SIZE);
+#else
+#define __vdso_u_arch_data
+#endif
+
#define VDSO_VVAR_SYMS \
PROVIDE(vdso_u_data = . - __VDSO_PAGES * PAGE_SIZE); \
PROVIDE(vdso_u_time_data = vdso_u_data); \
__vdso_u_timens_data \
__vdso_u_rng_data \
+ __vdso_u_arch_data \
#endif /* !__ASSEMBLY__ */
diff --git a/lib/vdso_kernel/datastore.c b/lib/vdso_kernel/datastore.c
index 0d4f5317b508a54b4f3295f0335d1eefce74d78c..668cac8c4f80ac71d3f6de71e98e963bc65a1c15 100644
--- a/lib/vdso_kernel/datastore.c
+++ b/lib/vdso_kernel/datastore.c
@@ -24,6 +24,14 @@ struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data;
static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE);
#endif /* CONFIG_VDSO_GETRANDOM */
+#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
+static union {
+ struct vdso_arch_data data;
+ u8 page[VDSO_ARCH_DATA_SIZE];
+} vdso_arch_data_store __page_aligned_data;
+struct vdso_arch_data *vdso_k_arch_data = &vdso_arch_data_store.data;
+#endif
+
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
@@ -63,6 +71,12 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data));
break;
+ case VDSO_ARCH_PAGES_START ... VDSO_ARCH_PAGES_END:
+ if (!IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA))
+ return VM_FAULT_SIGBUS;
+ pfn = __phys_to_pfn(__pa_symbol(vdso_k_arch_data)) +
+ vmf->pgoff - VDSO_ARCH_PAGES_START;
+ break;
default:
return VM_FAULT_SIGBUS;
}
--
2.47.1
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