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Wed, 05 Jul 2023 12:00:48 -0700 (PDT) Received: from charlie.ba.rivosinc.com ([66.220.2.162]) by smtp.gmail.com with ESMTPSA id d7-20020a170902aa8700b001b0358848b0sm19323359plr.161.2023.07.05.12.00.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Jul 2023 12:00:48 -0700 (PDT) From: Charlie Jenkins To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: charlie@rivosinc.com, conor@kernel.org, paul.walmsley@sifive.com, palmer@rivosinc.com, aou@eecs.berkeley.edu, anup@brainfault.org, konstantin@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, mick@ics.forth.gr, jrtc27@jrtc27.com Subject: [RESEND PATCH v3 2/2] RISC-V: mm: Update documentation and include test Date: Wed, 5 Jul 2023 11:59:42 -0700 Message-ID: <20230705190002.384799-3-charlie@rivosinc.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230705190002.384799-1-charlie@rivosinc.com> References: <20230705190002.384799-1-charlie@rivosinc.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230705_120050_129540_A434F4DC X-CRM114-Status: GOOD ( 20.79 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Add documentation explaining the behavior of mmap. Include a simple test that ensures that mmap returns an address less than the hint address while there are still addresses available. Signed-off-by: Charlie Jenkins --- Documentation/riscv/vm-layout.rst | 22 +++++++++ arch/riscv/include/asm/pgtable.h | 8 +-- tools/testing/selftests/riscv/Makefile | 2 +- tools/testing/selftests/riscv/mm/.gitignore | 1 + tools/testing/selftests/riscv/mm/Makefile | 21 ++++++++ .../selftests/riscv/mm/testcases/mmap.c | 49 +++++++++++++++++++ 6 files changed, 99 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/riscv/mm/.gitignore create mode 100644 tools/testing/selftests/riscv/mm/Makefile create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap.c diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst index 5462c84f4723..a610c68c9f3f 100644 --- a/Documentation/riscv/vm-layout.rst +++ b/Documentation/riscv/vm-layout.rst @@ -133,3 +133,25 @@ RISC-V Linux Kernel SV57 ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel __________________|____________|__________________|_________|____________________________________________________________ + + +Userspace VAs +-------------------- +To maintain compatibility with software that relies on the VA space +with a maximum of 39-bits, the kernel will, by default, return virtual +return virtual addresses to userspace from a 48-bit range (sv48). This +default behavior is achieved by passing 0 into the hint address parameter +of mmap. + +Software can "opt-in" to receiving VAs from other VA space by providing +a hint address to mmap. A call to mmap is guaranteed to return an address +that will not override the unset left-aligned bits in the hint address, +unless there is no space left in the address space. If there is no space +available in the requested address space, an address in the next smallest +available address space will be returned. + +For example, in order to obtain 48-bit VA space, a hint address greater than +:code:`1 << 38` must be provided. Note that this is 38 due to sv39 userspace +ending at :code:`1 << 38` with the addresses beyond this and up to :code:`1 << 39` +being reserved for the kernel. Similarly, to obtain 57-bit VA space addresses, a +hint address greater than or equal to :code:`1 << 47` must be provided. diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 752e210c7547..5ac973193fab 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -841,14 +841,16 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32. * Note that PGDIR_SIZE must evenly divide TASK_SIZE. * Task size is: - * - 0x9fc00000 (~2.5GB) for RV32. - * - 0x4000000000 ( 256GB) for RV64 using SV39 mmu - * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu + * - 0x9fc00000 (~2.5GB) for RV32. + * - 0x4000000000 ( 256GB) for RV64 using SV39 mmu + * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu + * - 0x100000000000000 ( 64PB) for RV64 using SV57 mmu * * Note that PGDIR_SIZE must evenly divide TASK_SIZE since "RISC-V * Instruction Set Manual Volume II: Privileged Architecture" states that * "load and store effective addresses, which are 64bits, must have bits * 63–48 all equal to bit 47, or else a page-fault exception will occur." + * Similarly for SV57, bits 63–57 must be equal to bit 56. */ #ifdef CONFIG_64BIT #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2) diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile index 32a72902d045..0fee58f990ae 100644 --- a/tools/testing/selftests/riscv/Makefile +++ b/tools/testing/selftests/riscv/Makefile @@ -5,7 +5,7 @@ ARCH ?= $(shell uname -m 2>/dev/null || echo not) ifneq (,$(filter $(ARCH),riscv)) -RISCV_SUBTARGETS ?= hwprobe +RISCV_SUBTARGETS ?= hwprobe mm else RISCV_SUBTARGETS := endif diff --git a/tools/testing/selftests/riscv/mm/.gitignore b/tools/testing/selftests/riscv/mm/.gitignore new file mode 100644 index 000000000000..022ea0a3f7df --- /dev/null +++ b/tools/testing/selftests/riscv/mm/.gitignore @@ -0,0 +1 @@ +mmap \ No newline at end of file diff --git a/tools/testing/selftests/riscv/mm/Makefile b/tools/testing/selftests/riscv/mm/Makefile new file mode 100644 index 000000000000..d41a0b3d2ca2 --- /dev/null +++ b/tools/testing/selftests/riscv/mm/Makefile @@ -0,0 +1,21 @@ +# SPDX-License-Identifier: GPL-2.0 +# Originally tools/testing/selftests/arm64/signal + +# Additional include paths needed by kselftest.h and local headers +CFLAGS += -D_GNU_SOURCE -std=gnu99 -I. + +SRCS := $(filter-out testcases/testcases.c,$(wildcard testcases/*.c)) +PROGS := $(patsubst %.c,%,$(SRCS)) + +# Generated binaries to be installed by top KSFT script +TEST_GEN_PROGS := $(notdir $(PROGS)) + +# Get Kernel headers installed and use them. + +# Including KSFT lib.mk here will also mangle the TEST_GEN_PROGS list +# to account for any OUTPUT target-dirs optionally provided by +# the toplevel makefile +include ../../lib.mk + +$(TEST_GEN_PROGS): $(PROGS) + cp $(PROGS) $(OUTPUT)/ \ No newline at end of file diff --git a/tools/testing/selftests/riscv/mm/testcases/mmap.c b/tools/testing/selftests/riscv/mm/testcases/mmap.c new file mode 100644 index 000000000000..781576f4c14b --- /dev/null +++ b/tools/testing/selftests/riscv/mm/testcases/mmap.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include "../../kselftest_harness.h" + +TEST(sv57_test) +{ + // Only works on 64 bit + #if __riscv_xlen == 64 + // Place all of the hint addresses on the boundaries of mmap + // sv39, sv48, sv57 + // User addresses end at 1<<38, 1<<47, 1<<56 respectively + void *on_37_bits = (void *) (1UL << 37); + void *on_38_bits = (void *) (1UL << 38); + void *on_46_bits = (void *) (1UL << 46); + void *on_47_bits = (void *) (1UL << 47); + void *on_55_bits = (void *) (1UL << 55); + void *on_56_bits = (void *) (1UL << 56); + + int prot = PROT_READ | PROT_WRITE; + int flags = MAP_PRIVATE | MAP_ANONYMOUS; + + int *no_hint = mmap(NULL, 5*sizeof(int), prot, flags, 0, 0); + int *on_37_addr = mmap(on_37_bits, 5*sizeof(int), prot, flags, 0, 0); + int *on_38_addr = mmap(on_38_bits, 5*sizeof(int), prot, flags, 0, 0); + int *on_46_addr = mmap(on_46_bits, 5*sizeof(int), prot, flags, 0, 0); + int *on_47_addr = mmap(on_47_bits, 5*sizeof(int), prot, flags, 0, 0); + int *on_55_addr = mmap(on_55_bits, 5*sizeof(int), prot, flags, 0, 0); + int *on_56_addr = mmap(on_56_bits, 5*sizeof(int), prot, flags, 0, 0); + + EXPECT_NE(no_hint, MAP_FAILED); + EXPECT_NE(on_37_addr, MAP_FAILED); + EXPECT_NE(on_38_addr, MAP_FAILED); + EXPECT_NE(on_46_addr, MAP_FAILED); + EXPECT_NE(on_47_addr, MAP_FAILED); + EXPECT_NE(on_55_addr, MAP_FAILED); + EXPECT_NE(on_56_addr, MAP_FAILED); + + EXPECT_LT((unsigned long) no_hint, 1UL << 47); + EXPECT_LT((unsigned long) on_37_addr, 1UL << 38); + EXPECT_LT((unsigned long) on_38_addr, 1UL << 38); + EXPECT_LT((unsigned long) on_46_addr, 1UL << 38); + EXPECT_LT((unsigned long) on_47_addr, 1UL << 47); + EXPECT_LT((unsigned long) on_55_addr, 1UL << 47); + EXPECT_LT((unsigned long) on_56_addr, 1UL << 57); + #else + #endif +} + +TEST_HARNESS_MAIN