From 09d6775f503b393d0457c7126aa43208e1724004 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Wed, 16 Oct 2024 13:27:45 -0700 Subject: riscv: Add support for userspace pointer masking RISC-V supports pointer masking with a variable number of tag bits (which is called "PMLEN" in the specification) and which is configured at the next higher privilege level. Wire up the PR_SET_TAGGED_ADDR_CTRL and PR_GET_TAGGED_ADDR_CTRL prctls so userspace can request a lower bound on the number of tag bits and determine the actual number of tag bits. As with arm64's PR_TAGGED_ADDR_ENABLE, the pointer masking configuration is thread-scoped, inherited on clone() and fork() and cleared on execve(). Reviewed-by: Charlie Jenkins Tested-by: Charlie Jenkins Signed-off-by: Samuel Holland Link: https://lore.kernel.org/r/20241016202814.4061541-5-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- include/uapi/linux/prctl.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/uapi') diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 35791791a879..cefd656ebf43 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -230,7 +230,7 @@ struct prctl_mm_map { # define PR_PAC_APDBKEY (1UL << 3) # define PR_PAC_APGAKEY (1UL << 4) -/* Tagged user address controls for arm64 */ +/* Tagged user address controls for arm64 and RISC-V */ #define PR_SET_TAGGED_ADDR_CTRL 55 #define PR_GET_TAGGED_ADDR_CTRL 56 # define PR_TAGGED_ADDR_ENABLE (1UL << 0) @@ -244,6 +244,9 @@ struct prctl_mm_map { # define PR_MTE_TAG_MASK (0xffffUL << PR_MTE_TAG_SHIFT) /* Unused; kept only for source compatibility */ # define PR_MTE_TCF_SHIFT 1 +/* RISC-V pointer masking tag length */ +# define PR_PMLEN_SHIFT 24 +# define PR_PMLEN_MASK (0x7fUL << PR_PMLEN_SHIFT) /* Control reclaim behavior when allocating memory */ #define PR_SET_IO_FLUSHER 57 -- cgit v1.2.3 From 78844482a1c939a972681842f8ee2a8ddb202441 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Wed, 16 Oct 2024 13:27:47 -0700 Subject: riscv: Allow ptrace control of the tagged address ABI This allows a tracer to control the ABI of the tracee, as on arm64. Signed-off-by: Samuel Holland Link: https://lore.kernel.org/r/20241016202814.4061541-7-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/ptrace.c | 42 ++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/elf.h | 1 + 2 files changed, 43 insertions(+) (limited to 'include/uapi') diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 92731ff8c79a..ea67e9fb7a58 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -28,6 +28,9 @@ enum riscv_regset { #ifdef CONFIG_RISCV_ISA_V REGSET_V, #endif +#ifdef CONFIG_RISCV_ISA_SUPM + REGSET_TAGGED_ADDR_CTRL, +#endif }; static int riscv_gpr_get(struct task_struct *target, @@ -152,6 +155,35 @@ static int riscv_vr_set(struct task_struct *target, } #endif +#ifdef CONFIG_RISCV_ISA_SUPM +static int tagged_addr_ctrl_get(struct task_struct *target, + const struct user_regset *regset, + struct membuf to) +{ + long ctrl = get_tagged_addr_ctrl(target); + + if (IS_ERR_VALUE(ctrl)) + return ctrl; + + return membuf_write(&to, &ctrl, sizeof(ctrl)); +} + +static int tagged_addr_ctrl_set(struct task_struct *target, + const struct user_regset *regset, + unsigned int pos, unsigned int count, + const void *kbuf, const void __user *ubuf) +{ + int ret; + long ctrl; + + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ctrl, 0, -1); + if (ret) + return ret; + + return set_tagged_addr_ctrl(target, ctrl); +} +#endif + static const struct user_regset riscv_user_regset[] = { [REGSET_X] = { .core_note_type = NT_PRSTATUS, @@ -182,6 +214,16 @@ static const struct user_regset riscv_user_regset[] = { .set = riscv_vr_set, }, #endif +#ifdef CONFIG_RISCV_ISA_SUPM + [REGSET_TAGGED_ADDR_CTRL] = { + .core_note_type = NT_RISCV_TAGGED_ADDR_CTRL, + .n = 1, + .size = sizeof(long), + .align = sizeof(long), + .regset_get = tagged_addr_ctrl_get, + .set = tagged_addr_ctrl_set, + }, +#endif }; static const struct user_regset_view riscv_user_native_view = { diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index b9935988da5c..a920cf8934dc 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -450,6 +450,7 @@ typedef struct elf64_shdr { #define NT_MIPS_MSA 0x802 /* MIPS SIMD registers */ #define NT_RISCV_CSR 0x900 /* RISC-V Control and Status Registers */ #define NT_RISCV_VECTOR 0x901 /* RISC-V vector registers */ +#define NT_RISCV_TAGGED_ADDR_CTRL 0x902 /* RISC-V tagged address control (prctl()) */ #define NT_LOONGARCH_CPUCFG 0xa00 /* LoongArch CPU config registers */ #define NT_LOONGARCH_CSR 0xa01 /* LoongArch control and status registers */ #define NT_LOONGARCH_LSX 0xa02 /* LoongArch Loongson SIMD Extension registers */ -- cgit v1.2.3