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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=1761238267; l=5718; i=debug@rivosinc.com; s=20251023; h=from:subject:message-id; bh=nTPZyNBNXm6/CcBEgex+4RYKED4Z+c7hR2hQbyF4T7Q=; b=jVEGpJ5fOHaE/PBKTfFkdz54GjVoFhiyMmL9dxcCE2pbGMmsR6LWmchxWivXqD7Y1A8ZEFV+P up4JZGQoAGrBGQjkLupb9lcggEEYPaHyP8i4XYaXAMXGEruAzHVGNPv 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-Stat-Signature: sqfn9ek14tsuqzhedh336smbydffz1tk X-Rspamd-Queue-Id: 9119C40009 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761238278-465694 X-HE-Meta: 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 OtErR1Us 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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 08620bdae696..2ebe789caa6b 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 @@ -371,3 +400,53 @@ 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