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Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li , Deepak Gupta X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1762994618; l=5718; i=debug@rivosinc.com; s=20251023; h=from:subject:message-id; bh=yFCOzn/pyDccak0xANk/vKLfOoWrfQcAvujrS/kNvhE=; b=EtFDJebpS2KNv9z97B4rIrgMJUXPW+AdSiq3o/RzvI757+wbuWYnE+/AHC45WEAhwOxJkPmyB EbAKcn3BonDBKpWXk8YBfDoiK5UgJbXTHakpPuQADinZKtfH6iLtPd1 X-Developer-Key: i=debug@rivosinc.com; a=ed25519; pk=O37GQv1thBhZToXyQKdecPDhtWVbEDRQ0RIndijvpjk= X-Endpoint-Received: by B4 Relay for debug@rivosinc.com/20251023 with auth_id=553 X-Original-From: Deepak Gupta Reply-To: debug@rivosinc.com X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 213FE120004 X-Stat-Signature: ujjfbxiqjb7q5d88jqic45yeetskennz X-HE-Tag: 1762994629-162207 X-HE-Meta: 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 4l8wH0pu 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Deepak Gupta prctls implemented are: PR_SET_INDIR_BR_LP_STATUS, PR_GET_INDIR_BR_LP_STATUS and PR_LOCK_INDIR_BR_LP_STATUS Reviewed-by: Zong Li Signed-off-by: Deepak Gupta --- arch/riscv/include/asm/usercfi.h | 14 +++++++ arch/riscv/kernel/entry.S | 4 ++ arch/riscv/kernel/process.c | 5 +++ arch/riscv/kernel/usercfi.c | 79 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 102 insertions(+) diff --git a/arch/riscv/include/asm/usercfi.h b/arch/riscv/include/asm/usercfi.h index d71093f414df..4501d741a609 100644 --- a/arch/riscv/include/asm/usercfi.h +++ b/arch/riscv/include/asm/usercfi.h @@ -16,6 +16,8 @@ struct kernel_clone_args; struct cfi_state { unsigned long ubcfi_en : 1; /* Enable for backward cfi. */ unsigned long ubcfi_locked : 1; + unsigned long ufcfi_en : 1; /* Enable for forward cfi. Note that ELP goes in sstatus */ + unsigned long ufcfi_locked : 1; unsigned long user_shdw_stk; /* Current user shadow stack pointer */ unsigned long shdw_stk_base; /* Base address of shadow stack */ unsigned long shdw_stk_size; /* size of shadow stack */ @@ -32,6 +34,10 @@ bool is_shstk_locked(struct task_struct *task); bool is_shstk_allocated(struct task_struct *task); void set_shstk_lock(struct task_struct *task); void set_shstk_status(struct task_struct *task, bool enable); +bool is_indir_lp_enabled(struct task_struct *task); +bool is_indir_lp_locked(struct task_struct *task); +void set_indir_lp_status(struct task_struct *task, bool enable); +void set_indir_lp_lock(struct task_struct *task); #define PR_SHADOW_STACK_SUPPORTED_STATUS_MASK (PR_SHADOW_STACK_ENABLE) @@ -57,6 +63,14 @@ void set_shstk_status(struct task_struct *task, bool enable); #define set_shstk_status(task, enable) do {} while (0) +#define is_indir_lp_enabled(task) false + +#define is_indir_lp_locked(task) false + +#define set_indir_lp_status(task, enable) do {} while (0) + +#define set_indir_lp_lock(task) do {} while (0) + #endif /* CONFIG_RISCV_USER_CFI */ #endif /* __ASSEMBLER__ */ diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 8410850953d6..036a6ca7641f 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -174,6 +174,10 @@ SYM_CODE_START(handle_exception) * or vector in kernel space. */ li t0, SR_SUM | SR_FS_VS +#ifdef CONFIG_64BIT + li t1, SR_ELP + or t0, t0, t1 +#endif REG_L s0, TASK_TI_USER_SP(tp) csrrc s1, CSR_STATUS, t0 diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index a137d3483646..49f527e3acfd 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -163,6 +163,11 @@ void start_thread(struct pt_regs *regs, unsigned long pc, set_shstk_status(current, false); set_shstk_base(current, 0, 0); set_active_shstk(current, 0); + /* + * disable indirect branch tracking on exec. + * libc will enable it later via prctl. + */ + set_indir_lp_status(current, false); #ifdef CONFIG_64BIT regs->status &= ~SR_UXL; diff --git a/arch/riscv/kernel/usercfi.c b/arch/riscv/kernel/usercfi.c index 0b77b812e4d7..a384ce9ed25c 100644 --- a/arch/riscv/kernel/usercfi.c +++ b/arch/riscv/kernel/usercfi.c @@ -72,6 +72,35 @@ void set_shstk_lock(struct task_struct *task) task->thread_info.user_cfi_state.ubcfi_locked = 1; } +bool is_indir_lp_enabled(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_en; +} + +bool is_indir_lp_locked(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_locked; +} + +void set_indir_lp_status(struct task_struct *task, bool enable) +{ + if (!cpu_supports_indirect_br_lp_instr()) + return; + + task->thread_info.user_cfi_state.ufcfi_en = enable ? 1 : 0; + + if (enable) + task->thread.envcfg |= ENVCFG_LPE; + else + task->thread.envcfg &= ~ENVCFG_LPE; + + csr_write(CSR_ENVCFG, task->thread.envcfg); +} + +void set_indir_lp_lock(struct task_struct *task) +{ + task->thread_info.user_cfi_state.ufcfi_locked = 1; +} /* * If size is 0, then to be compatible with regular stack we want it to be as big as * regular stack. Else PAGE_ALIGN it and return back @@ -370,3 +399,53 @@ int arch_lock_shadow_stack_status(struct task_struct *task, return 0; } + +int arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __user *status) +{ + unsigned long fcfi_status = 0; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is enabled on the task or not */ + fcfi_status |= (is_indir_lp_enabled(t) ? PR_INDIR_BR_LP_ENABLE : 0); + + return copy_to_user(status, &fcfi_status, sizeof(fcfi_status)) ? -EFAULT : 0; +} + +int arch_set_indir_br_lp_status(struct task_struct *t, unsigned long status) +{ + bool enable_indir_lp = false; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is locked and further can't be modified by user */ + if (is_indir_lp_locked(t)) + return -EINVAL; + + /* Reject unknown flags */ + if (status & ~PR_INDIR_BR_LP_ENABLE) + return -EINVAL; + + enable_indir_lp = (status & PR_INDIR_BR_LP_ENABLE); + set_indir_lp_status(t, enable_indir_lp); + + return 0; +} + +int arch_lock_indir_br_lp_status(struct task_struct *task, + unsigned long arg) +{ + /* + * If indirect branch tracking is not supported or not enabled on task, + * nothing to lock here + */ + if (!cpu_supports_indirect_br_lp_instr() || + !is_indir_lp_enabled(task) || arg != 0) + return -EINVAL; + + set_indir_lp_lock(task); + + return 0; +} -- 2.43.0