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Message-Id: <20241216-vdso-store-rng-v1-4-f7aed1bdb3b2@linutronix.de>
Date: Mon, 16 Dec 2024 15:10:00 +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 04/17] vdso: Add generic random data storage
Extend the generic vDSO data storage with a page for the random state data.
The random state data is stored in a dedicated page, as the existing
storage page is only meant for time-related, time-namespace-aware data.
This simplifies to access logic to not need to handle time namespaces
anymore and also frees up more space in the time-related page.
In case further generic vDSO data store is required it can be added to
the random state page.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
include/vdso/datapage.h | 24 ++++++++++++++++++++++++
lib/vdso_kernel/datastore.c | 14 ++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 69af424413db1f265607d0f1bdbf88550548c5ba..5ce322422fcb7ba77aeafddbf132fd3e5dbc5a0c 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -145,8 +145,10 @@ extern struct vdso_rng_data _vdso_rng_data __attribute__((visibility("hidden")))
#else
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 struct vdso_time_data *vdso_k_time_data;
+extern struct vdso_rng_data *vdso_k_rng_data;
#endif
/**
@@ -162,6 +164,7 @@ union vdso_data_store {
enum vdso_pages {
VDSO_TIME_PAGE_OFFSET,
VDSO_TIMENS_PAGE_OFFSET,
+ VDSO_RNG_PAGE_OFFSET,
VDSO_NR_PAGES
};
@@ -185,6 +188,20 @@ static __always_inline const struct vdso_time_data *__arch_get_vdso_u_timens_dat
#define __arch_get_timens_vdso_data(vd) __arch_get_vdso_u_timens_data()
#endif /* CONFIG_TIME_NS */
+#ifdef CONFIG_VDSO_GETRANDOM
+static __always_inline const struct vdso_rng_data *__arch_get_vdso_u_rng_data(void)
+{
+ return &vdso_u_rng_data;
+}
+#define __arch_get_vdso_rng_data __arch_get_vdso_u_rng_data
+
+static __always_inline struct vdso_rng_data *__arch_get_vdso_k_rng_data(void)
+{
+ return vdso_k_rng_data;
+}
+#define __arch_get_k_vdso_rng_data __arch_get_vdso_k_rng_data
+#endif /* CONFIG_VDSO_GETRANDOM */
+
#endif /* CONFIG_GENERIC_VDSO_DATA_STORE */
/*
@@ -211,10 +228,17 @@ static __always_inline const struct vdso_time_data *__arch_get_vdso_u_timens_dat
#define __vdso_u_timens_data
#endif
+#ifdef CONFIG_VDSO_GETRANDOM
+#define __vdso_u_rng_data PROVIDE(vdso_u_rng_data = vdso_u_data + 2 * PAGE_SIZE);
+#else
+#define __vdso_u_rng_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 \
#endif /* !__ASSEMBLY__ */
diff --git a/lib/vdso_kernel/datastore.c b/lib/vdso_kernel/datastore.c
index c9cd269b1ed1b6cdd5fdf9fe929d0b778314b962..0d4f5317b508a54b4f3295f0335d1eefce74d78c 100644
--- a/lib/vdso_kernel/datastore.c
+++ b/lib/vdso_kernel/datastore.c
@@ -15,6 +15,15 @@ static union vdso_data_store vdso_time_data_store __page_aligned_data;
struct vdso_time_data *vdso_k_time_data = vdso_time_data_store.data;
static_assert(sizeof(vdso_time_data_store) == PAGE_SIZE);
+#ifdef CONFIG_VDSO_GETRANDOM
+static union {
+ struct vdso_rng_data data;
+ u8 page[PAGE_SIZE];
+} vdso_rng_data_store __page_aligned_data;
+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 */
+
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
@@ -49,6 +58,11 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
return VM_FAULT_SIGBUS;
pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data));
break;
+ case VDSO_RNG_PAGE_OFFSET:
+ if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+ return VM_FAULT_SIGBUS;
+ pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data));
+ break;
default:
return VM_FAULT_SIGBUS;
}
--
2.47.1
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