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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 , Andreas Korb , Valentin Haudiquet , Deepak Gupta X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1765473664; l=5844; i=debug@rivosinc.com; s=20251023; h=from:subject:message-id; bh=wFkoKafNuhuo5Khjoh4DbWfgN2zX7rAU3xJ3b3Vz/iA=; b=KNp9Df1Xy3jjdBJ66JMCtZKCAlsxxgs14113q7TFnm++4BGOo+0whVLyN1ucgVBUeyaapTI2f JMx65ciy1GNA9RXeAYm70vHEy/W8CAwkhtBuTW5HzfJJl7q+t5H3mQ2 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-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CFAA980014 X-Stat-Signature: igqwm7rt1sztwgdtxtnoh6ufg6hehnko X-Rspam-User: X-HE-Tag: 1765473675-748101 X-HE-Meta: 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 og3Bn2Ib 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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 Tested-by: Andreas Korb Tested-by: Valentin Haudiquet 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