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arm64: Support passing more registers to signals
To support recent extensions to the Arm architecture we may need to store more or larger registers when sending a signal. To support this create a list of these extra registers. Userspace that needs to access a register in the signal handler can then walk the list to find the correct register struct and read/write its contents. Reviewed by: kib, markj (earlier version) Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D43302
This commit is contained in:
Andrew Turner
parent
69d5783ae8
commit
7e6437c084
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@ -461,8 +461,12 @@ int
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set_mcontext(struct thread *td, mcontext_t *mcp)
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{
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#define PSR_13_MASK 0xfffffffful
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struct arm64_reg_context ctx;
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struct trapframe *tf = td->td_frame;
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uint64_t spsr;
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vm_offset_t addr;
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int error;
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bool done;
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spsr = mcp->mc_gpregs.gp_spsr;
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#ifdef COMPAT_FREEBSD13
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@ -501,8 +505,35 @@ set_mcontext(struct thread *td, mcontext_t *mcp)
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READ_SPECIALREG(mdscr_el1) | MDSCR_SS);
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isb();
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}
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set_fpcontext(td, mcp);
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/* Read any register contexts we find */
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if (mcp->mc_ptr != 0) {
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addr = mcp->mc_ptr;
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done = false;
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do {
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if (!__is_aligned(addr,
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_Alignof(struct arm64_reg_context)))
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return (EINVAL);
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error = copyin((const void *)addr, &ctx, sizeof(ctx));
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if (error != 0)
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return (error);
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switch (ctx.ctx_id) {
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case ARM64_CTX_END:
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done = true;
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break;
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default:
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return (EINVAL);
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}
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addr += ctx.ctx_size;
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} while (!done);
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}
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return (0);
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#undef PSR_13_MASK
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}
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@ -585,6 +616,31 @@ sys_sigreturn(struct thread *td, struct sigreturn_args *uap)
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return (EJUSTRETURN);
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}
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static bool
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sendsig_ctx_end(struct thread *td, vm_offset_t *addrp)
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{
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struct arm64_reg_context end_ctx;
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vm_offset_t ctx_addr;
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*addrp -= sizeof(end_ctx);
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ctx_addr = *addrp;
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memset(&end_ctx, 0, sizeof(end_ctx));
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end_ctx.ctx_id = ARM64_CTX_END;
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end_ctx.ctx_size = sizeof(end_ctx);
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if (copyout(&end_ctx, (void *)ctx_addr, sizeof(end_ctx)) != 0)
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return (false);
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return (true);
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}
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typedef bool(*ctx_func)(struct thread *, vm_offset_t *);
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static const ctx_func ctx_funcs[] = {
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sendsig_ctx_end, /* Must be first to end the linked list */
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NULL,
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};
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void
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sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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{
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@ -593,6 +649,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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struct trapframe *tf;
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struct sigframe *fp, frame;
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struct sigacts *psp;
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vm_offset_t addr;
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int onstack, sig;
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td = curthread;
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@ -612,19 +669,15 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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/* Allocate and validate space for the signal handler context. */
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if ((td->td_pflags & TDP_ALTSTACK) != 0 && !onstack &&
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SIGISMEMBER(psp->ps_sigonstack, sig)) {
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fp = (struct sigframe *)((uintptr_t)td->td_sigstk.ss_sp +
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addr = ((uintptr_t)td->td_sigstk.ss_sp +
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td->td_sigstk.ss_size);
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#if defined(COMPAT_43)
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td->td_sigstk.ss_flags |= SS_ONSTACK;
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#endif
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} else {
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fp = (struct sigframe *)td->td_frame->tf_sp;
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addr = td->td_frame->tf_sp;
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}
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/* Make room, keeping the stack aligned */
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fp--;
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fp = (struct sigframe *)STACKALIGN(fp);
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/* Fill in the frame to copy out */
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bzero(&frame, sizeof(frame));
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get_mcontext(td, &frame.sf_uc.uc_mcontext, 0);
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@ -636,6 +689,26 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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mtx_unlock(&psp->ps_mtx);
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PROC_UNLOCK(td->td_proc);
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for (int i = 0; ctx_funcs[i] != NULL; i++) {
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if (!ctx_funcs[i](td, &addr)) {
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/* Process has trashed its stack. Kill it. */
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CTR4(KTR_SIG,
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"sendsig: frame sigexit td=%p fp=%#lx func[%d]=%p",
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td, addr, i, ctx_funcs[i]);
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PROC_LOCK(p);
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sigexit(td, SIGILL);
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/* NOTREACHED */
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}
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}
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/* Point at the first context */
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frame.sf_uc.uc_mcontext.mc_ptr = addr;
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/* Make room, keeping the stack aligned */
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fp = (struct sigframe *)addr;
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fp--;
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fp = (struct sigframe *)STACKALIGN(fp);
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/* Copy the sigframe out to the user's stack. */
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if (copyout(&frame, fp, sizeof(*fp)) != 0) {
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/* Process has trashed its stack. Kill it. */
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@ -51,15 +51,29 @@ struct fpregs {
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int fp_pad;
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};
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/*
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* Support for registers that don't fit into gpregs or fpregs, e.g. SVE.
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* There are some registers that have been added so are optional. To support
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* these create an array of headers that point at the register data.
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*/
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struct arm64_reg_context {
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__uint32_t ctx_id;
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__uint32_t ctx_size;
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};
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#define ARM64_CTX_END 0xa5a5a5a5
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struct __mcontext {
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struct gpregs mc_gpregs;
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struct fpregs mc_fpregs;
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int mc_flags;
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#define _MC_FP_VALID 0x1 /* Set when mc_fpregs has valid data */
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int mc_pad; /* Padding */
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__uint64_t mc_spare[8]; /* Space for expansion, set to zero */
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__uint64_t mc_ptr; /* Address of extra_regs struct */
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__uint64_t mc_spare[7]; /* Space for expansion, set to zero */
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};
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typedef struct __mcontext mcontext_t;
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#ifdef COMPAT_FREEBSD32
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