From mboxrd@z Thu Jan 1 00:00:00 1970 From: Conor Dooley Date: Wed, 1 Mar 2023 18:27:31 +0000 Subject: [PATCH -next v14 13/19] riscv: signal: Add sigcontext save/restore for vector In-Reply-To: <20230224170118.16766-14-andy.chiu@sifive.com> References: <20230224170118.16766-1-andy.chiu@sifive.com> <20230224170118.16766-14-andy.chiu@sifive.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Feb 24, 2023 at 05:01:12PM +0000, Andy Chiu wrote: > From: Greentime Hu > > This patch facilitates the existing fp-reserved words for placement of > the first extension's context header on the user's sigframe. A context > header consists of a distinct magic word and the size, including the > header itself, of an extension on the stack. Then, the frame is followed > by the context of that extension, and then a header + context body for > another extension if exists. If there is no more extension to come, then > the frame must be ended with a null context header. A special case is > rv64gc, where the kernel support no extensions requiring to expose > additional regfile to the user. In such case the kernel would place the > null context header right after the first reserved word of > __riscv_q_ext_state when saving sigframe. And the kernel would check if > all reserved words are zeros when a signal handler returns. > > __riscv_q_ext_state---->| |<-__riscv_extra_ext_header > ~ ~ > .reserved[0]--->|0 |<- .reserved > <-------|magic |<- .hdr > | |size |_______ end of sc_fpregs > | |ext-bdy| > | ~ ~ > +)size ------->|magic |<- another context header > |size | > |ext-bdy| > ~ ~ > |magic:0|<- null context header > |size:0 | > > The vector registers will be saved in datap pointer. The datap pointer > will be allocated dynamically when the task needs in kernel space. On > the other hand, datap pointer on the sigframe will be set right after > the __riscv_v_ext_state data structure. > > Co-developed-by: Vincent Chen > Signed-off-by: Vincent Chen > Signed-off-by: Greentime Hu > Suggested-by: Vineet Gupta > Suggested-by: Richard Henderson > Signed-off-by: Andy Chiu > --- > +static long save_v_state(struct pt_regs *regs, void **sc_vec) > +{ > + /* > + * Put __sc_riscv_v_state to the user's signal context space pointed > + * by sc_vec and the datap point the address right > + * after __sc_riscv_v_state. > + */ AFAIU, this comment describes the assignments here. I think it would be significantly clearer if you defined the variables here & moved the assignment and comment further down the function. > + struct __riscv_ctx_hdr __user *hdr = (struct __riscv_ctx_hdr *)(*sc_vec); > + struct __sc_riscv_v_state __user *state = (struct __sc_riscv_v_state *)(hdr + 1); > + void __user *datap = state + 1; > + long err; > + > + /* datap is designed to be 16 byte aligned for better performance */ > + WARN_ON(unlikely(!IS_ALIGNED((unsigned long)datap, 16))); > + > + riscv_v_vstate_save(current, regs); > + /* Copy everything of vstate but datap. */ > + err = __copy_to_user(&state->v_state, ¤t->thread.vstate, > + offsetof(struct __riscv_v_ext_state, datap)); > + /* Copy the pointer datap itself. */ > + err |= __put_user(datap, &state->v_state.datap); > + /* Copy the whole vector content to user space datap. */ > + err |= __copy_to_user(datap, current->thread.vstate.datap, riscv_v_vsize); > + /* Copy magic to the user space after saving all vector conetext */ > + err |= __put_user(RISCV_V_MAGIC, &hdr->magic); > + err |= __put_user(riscv_v_sc_size, &hdr->size); > + if (unlikely(err)) > + return err; > + > + /* Only progress the sv_vec if everything has done successfully */ > + *sc_vec += riscv_v_sc_size; > + return 0; > +} > static long restore_sigcontext(struct pt_regs *regs, > struct sigcontext __user *sc) > { > + void *sc_ext_ptr = &sc->sc_extdesc.hdr; > + __u32 rsvd; > long err; > - size_t i; > - > /* sc_regs is structured the same as the start of pt_regs */ > err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs)); > if (unlikely(err)) > - return err; > + goto done; > /* Restore the floating-point state. */ > if (has_fpu()) { > err = restore_fp_state(regs, &sc->sc_fpregs); > if (unlikely(err)) > - return err; > + goto done; > } > > - /* We support no other extension state at this time. */ > - for (i = 0; i < ARRAY_SIZE(sc->sc_fpregs.q.reserved); i++) { > - u32 value; > - > - err = __get_user(value, &sc->sc_fpregs.q.reserved[i]); > - if (unlikely(err)) > + /* Check the reserved word before extensions parsing */ > + err = __get_user(rsvd, &sc->sc_extdesc.reserved); > + if (unlikely(err)) > + goto done; > + if (unlikely(rsvd)) > + goto invalid; > + > + while (1 && !err) { This is just while (!err), no? > + __u32 magic, size; > + struct __riscv_ctx_hdr *head = (struct __riscv_ctx_hdr *)sc_ext_ptr; > + > + err |= __get_user(magic, &head->magic); > + err |= __get_user(size, &head->size); > + if (err) > + goto done; > + > + sc_ext_ptr += sizeof(struct __riscv_ctx_hdr); > + switch (magic) { > + case END_MAGIC: > + if (size != END_HDR_SIZE) > + goto invalid; > + goto done; > + case RISCV_V_MAGIC: > + if (!has_vector() || !riscv_v_vstate_query(regs)) > + goto invalid; > + if (size != riscv_v_sc_size) > + goto invalid; > + err = __restore_v_state(regs, sc_ext_ptr); > break; > - if (value != 0) > - return -EINVAL; > + default: > + goto invalid; Why does this need a goto, rather than returning -EINVAL directly? > + } > + sc_ext_ptr = ((void *)(head) + size); > } > +done: > return err; > +invalid: > + return -EINVAL; > +} -------------- next part -------------- A non-text attachment was scrubbed... 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