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Levin" , Andrea Bolognani , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Thomas Gleixner , Ron Economos , Andrew Jones , Quan Zhou , Felix Yan , Ruizhe Pan , Guo Ren , Yao Zi , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org, =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= Subject: Re: [PATCH v6 1/3] riscv/ptrace: add new regset to access original a0 register Message-ID: References: <20250115-riscv-new-regset-v6-0-59bfddd33525@coelacanthus.name> <20250115-riscv-new-regset-v6-1-59bfddd33525@coelacanthus.name> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250115-riscv-new-regset-v6-1-59bfddd33525@coelacanthus.name> On Wed, Jan 15, 2025 at 07:13:27PM +0800, Celeste Liu wrote: > The orig_a0 is missing in struct user_regs_struct of riscv, and there is > no way to add it without breaking UAPI. (See Link tag below) > > Like NT_ARM_SYSTEM_CALL do, we add a new regset name NT_RISCV_ORIG_A0 to > access original a0 register from userspace via ptrace API. > > Fixes: e2c0cdfba7f6 ("RISC-V: User-facing API") > Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/ > Cc: stable@vger.kernel.org > Reviewed-by: Björn Töpel > Signed-off-by: Celeste Liu Thank you! Reviewed-by: Charlie Jenkins Tested-by: Charlie Jenkins > --- > arch/riscv/kernel/ptrace.c | 32 ++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 2 files changed, 33 insertions(+) > > diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c > index ea67e9fb7a583683b922fe2c017ea61f3bc848db..ef9ab74c8575a5c440155973b1c625c06a867c97 100644 > --- a/arch/riscv/kernel/ptrace.c > +++ b/arch/riscv/kernel/ptrace.c > @@ -31,6 +31,7 @@ enum riscv_regset { > #ifdef CONFIG_RISCV_ISA_SUPM > REGSET_TAGGED_ADDR_CTRL, > #endif > + REGSET_ORIG_A0, > }; > > static int riscv_gpr_get(struct task_struct *target, > @@ -184,6 +185,29 @@ static int tagged_addr_ctrl_set(struct task_struct *target, > } > #endif > > +static int riscv_orig_a0_get(struct task_struct *target, > + const struct user_regset *regset, > + struct membuf to) > +{ > + return membuf_store(&to, task_pt_regs(target)->orig_a0); > +} > + > +static int riscv_orig_a0_set(struct task_struct *target, > + const struct user_regset *regset, > + unsigned int pos, unsigned int count, > + const void *kbuf, const void __user *ubuf) > +{ > + unsigned long orig_a0 = task_pt_regs(target)->orig_a0; > + int ret; > + > + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &orig_a0, 0, -1); > + if (ret) > + return ret; > + > + task_pt_regs(target)->orig_a0 = orig_a0; > + return 0; > +} > + > static const struct user_regset riscv_user_regset[] = { > [REGSET_X] = { > .core_note_type = NT_PRSTATUS, > @@ -224,6 +248,14 @@ static const struct user_regset riscv_user_regset[] = { > .set = tagged_addr_ctrl_set, > }, > #endif > + [REGSET_ORIG_A0] = { > + .core_note_type = NT_RISCV_ORIG_A0, > + .n = 1, > + .size = sizeof(elf_greg_t), > + .align = sizeof(elf_greg_t), > + .regset_get = riscv_orig_a0_get, > + .set = riscv_orig_a0_set, > + }, > }; > > 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 b44069d29cecc0f9de90ee66bfffd2137f4275a8..390060229601631da2fb27030d9fa2142e676c14 100644 > --- a/include/uapi/linux/elf.h > +++ b/include/uapi/linux/elf.h > @@ -452,6 +452,7 @@ typedef struct elf64_shdr { > #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_RISCV_ORIG_A0 0x903 /* RISC-V original a0 register */ > #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 */ > > -- > 2.48.0 >