linux(4): Implement signal trampoline for arm64 in a FreeBSD-way
The implemenation differs from others Linuxulators. For unwinders Linux ucontext_t is stored, however native machine context is used to store/restore process state to avoid code duplication. As DWARF Aarch64 does not define a register number for PC and provides no direct way to encode the PC of the previous frame, CFI cannot describe a signal trampoline frame. So, modified the vdso linker script to discard unused sections. Extensions are not implemented. MFC after: 2 weeks
This commit is contained in:
Dmitry Chagin
parent
08e201a3b4
commit
c56480a832
@ -164,7 +164,7 @@ struct l_newstat {
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#define LINUX_SIG_SETMASK 2
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/* sigaltstack */
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#define LINUX_MINSIGSTKSZ 2048 /* XXX */
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#define LINUX_MINSIGSTKSZ 5664 /* sigframe */
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typedef void (*l_handler_t)(l_int);
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@ -3,6 +3,7 @@
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*
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* Copyright (C) 2018 Turing Robotic Industries Inc.
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* Copyright (C) 2020 Andrew Turner <andrew@FreeBSD.org>
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* Copyright (C) 2022 Dmitry Chagin <dchagin@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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@ -29,7 +30,7 @@
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*/
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/*
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* arm64 Linux VDSO implementation.
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* arm64 Linux VDSO signal trampoline.
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*/
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#include <machine/asm.h>
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@ -45,8 +46,14 @@ linux_platform:
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.text
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nop /* This is what Linux calls a "Mysterious NOP". */
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ENTRY(__kernel_rt_sigreturn)
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EENTRY(__kernel_rt_sigreturn)
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mov x8, #LINUX_SYS_linux_rt_sigreturn
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svc #0
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ret
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END(__kernel_rt_sigreturn)
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EEND(__kernel_rt_sigreturn)
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EENTRY(linux_vdso_sigcode)
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blr x8
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mov x8, #LINUX_SYS_linux_rt_sigreturn
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svc #0
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EEND(linux_vdso_sigcode)
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@ -1,7 +1,7 @@
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/*-
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* Copyright (c) 1994-1996 Søren Schmidt
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* Copyright (c) 2013 Dmitry Chagin <dchagin@FreeBSD.org>
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* Copyright (c) 2018 Turing Robotic Industries Inc.
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* Copyright (c) 2022 Dmitry Chagin <dchagin@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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@ -23,22 +23,62 @@
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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*
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* $FreeBSD$
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*/
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#ifndef _ARM64_LINUX_SIGFRAME_H_
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#define _ARM64_LINUX_SIGFRAME_H_
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/*
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* This structure is different from the one used by Linux,
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* but it doesn't matter - it's not user-accessible. We need
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* it instead of the native one because of l_siginfo.
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*/
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struct _l_aarch64_ctx {
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uint32_t magic;
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uint32_t size;
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};
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#define L_FPSIMD_MAGIC 0x46508001
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#define L_ESR_MAGIC 0x45535201
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struct l_fpsimd_context {
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struct _l_aarch64_ctx head;
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uint32_t fpsr;
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uint32_t fpcr;
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__uint128_t vregs[32];
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};
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struct l_esr_context {
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struct _l_aarch64_ctx head;
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uint64_t esr;
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};
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struct l_sigcontext {
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uint64_t fault_address;
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uint64_t regs[31];
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uint64_t sp;
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uint64_t pc;
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uint64_t pstate;
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uint8_t __reserved[4096] __attribute__((__aligned__(16)));
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};
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struct l_ucontext {
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unsigned long uc_flags;
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struct l_ucontext *uc_link;
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l_stack_t uc_stack;
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l_sigset_t uc_sigmask;
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uint8_t __glibc_hole[1024 / 8 - sizeof(l_sigset_t)];
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struct l_sigcontext uc_sc;
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};
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struct l_rt_sigframe {
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l_siginfo_t sf_si;
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struct l_ucontext sf_uc;
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} __attribute__((__aligned__(16)));
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struct l_sigframe {
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struct l_siginfo sf_si;
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ucontext_t sf_uc;
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struct l_rt_sigframe sf;
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/* frame_record */
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uint64_t fp;
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uint64_t lr;
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ucontext_t uc;
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};
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#endif /* _ARM64_LINUX_SIGFRAME_H_ */
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@ -128,7 +128,7 @@ LIN_SDT_PROBE_DEFINE0(sysvec, linux_elf_fixup, todo);
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LINUX_VDSO_SYM_CHAR(linux_platform);
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LINUX_VDSO_SYM_INTPTR(kern_timekeep_base);
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LINUX_VDSO_SYM_INTPTR(__kernel_rt_sigreturn);
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LINUX_VDSO_SYM_INTPTR(linux_vdso_sigcode);
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/* LINUXTODO: do we have traps to translate? */
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static int
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@ -405,21 +405,23 @@ linux_exec_setregs(struct thread *td, struct image_params *imgp,
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int
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linux_rt_sigreturn(struct thread *td, struct linux_rt_sigreturn_args *args)
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{
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struct l_sigframe frame;
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struct l_sigframe *frame;
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ucontext_t uc;
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struct trapframe *tf;
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int error;
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tf = td->td_frame;
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frame = (struct l_sigframe *)tf->tf_sp;
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if (copyin((void *)tf->tf_sp, &frame, sizeof(frame)))
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if (copyin((void *)&frame->uc, &uc, sizeof(uc)))
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return (EFAULT);
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error = set_mcontext(td, &frame.sf_uc.uc_mcontext);
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error = set_mcontext(td, &uc.uc_mcontext);
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if (error != 0)
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return (error);
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/* Restore signal mask. */
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kern_sigprocmask(td, SIG_SETMASK, &frame.sf_uc.uc_sigmask, NULL, 0);
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kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask, NULL, 0);
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return (EJUSTRETURN);
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}
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@ -430,7 +432,12 @@ linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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struct thread *td;
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struct proc *p;
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struct trapframe *tf;
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struct l_sigframe *fp, frame;
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struct l_sigframe *fp, *frame;
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struct l_fpsimd_context *fpsimd;
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struct l_esr_context *esr;
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l_stack_t uc_stack;
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ucontext_t uc;
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uint8_t *scr;
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struct sigacts *psp;
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int onstack, sig;
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@ -464,36 +471,77 @@ linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
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fp--;
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fp = (struct l_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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get_mcontext(td, &uc.uc_mcontext, 0);
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uc.uc_sigmask = *mask;
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/* Translate the signal. */
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sig = bsd_to_linux_signal(sig);
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siginfo_to_lsiginfo(&ksi->ksi_info, &frame.sf_si, sig);
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frame.sf_uc.uc_sigmask = *mask;
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frame.sf_uc.uc_stack = td->td_sigstk;
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frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
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(onstack ? SS_ONSTACK : 0) : SS_DISABLE;
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uc_stack.ss_sp = PTROUT(td->td_sigstk.ss_sp);
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uc_stack.ss_size = td->td_sigstk.ss_size;
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uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
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(onstack ? LINUX_SS_ONSTACK : 0) : LINUX_SS_DISABLE;
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mtx_unlock(&psp->ps_mtx);
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PROC_UNLOCK(td->td_proc);
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/* Fill in the frame to copy out */
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frame = malloc(sizeof(*frame), M_LINUX, M_WAITOK | M_ZERO);
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memcpy(&frame->sf.sf_uc.uc_sc.regs, tf->tf_x, sizeof(tf->tf_x));
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frame->sf.sf_uc.uc_sc.regs[30] = tf->tf_lr;
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frame->sf.sf_uc.uc_sc.sp = tf->tf_sp;
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frame->sf.sf_uc.uc_sc.pc = tf->tf_lr;
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frame->sf.sf_uc.uc_sc.pstate = tf->tf_spsr;
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frame->sf.sf_uc.uc_sc.fault_address = (register_t)ksi->ksi_addr;
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/* Stack frame for unwinding */
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frame->fp = tf->tf_x[29];
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frame->lr = tf->tf_lr;
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/* Translate the signal. */
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sig = bsd_to_linux_signal(sig);
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siginfo_to_lsiginfo(&ksi->ksi_info, &frame->sf.sf_si, sig);
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bsd_to_linux_sigset(mask, &frame->sf.sf_uc.uc_sigmask);
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/*
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* Prepare fpsimd & esr. Does not check sizes, as
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* __reserved is big enougth.
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*/
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scr = (uint8_t *)&frame->sf.sf_uc.uc_sc.__reserved;
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#ifdef VFP
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fpsimd = (struct l_fpsimd_context *) scr;
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fpsimd->head.magic = L_FPSIMD_MAGIC;
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fpsimd->head.size = sizeof(struct l_fpsimd_context);
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fpsimd->fpsr = uc.uc_mcontext.mc_fpregs.fp_sr;
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fpsimd->fpcr = uc.uc_mcontext.mc_fpregs.fp_cr;
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memcpy(fpsimd->vregs, &uc.uc_mcontext.mc_fpregs.fp_q,
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sizeof(uc.uc_mcontext.mc_fpregs.fp_q));
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scr += roundup(sizeof(struct l_fpsimd_context), 16);
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#endif
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if (ksi->ksi_addr != 0) {
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esr = (struct l_esr_context *) scr;
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esr->head.magic = L_ESR_MAGIC;
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esr->head.size = sizeof(struct l_esr_context);
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esr->esr = tf->tf_esr;
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}
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memcpy(&frame->sf.sf_uc.uc_stack, &uc_stack, sizeof(uc_stack));
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memcpy(&frame->uc, &uc, sizeof(uc));
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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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if (copyout(frame, fp, sizeof(*fp)) != 0) {
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/* Process has trashed its stack. Kill it. */
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free(frame, M_LINUX);
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CTR2(KTR_SIG, "sendsig: sigexit td=%p fp=%p", td, fp);
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PROC_LOCK(p);
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sigexit(td, SIGILL);
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}
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free(frame, M_LINUX);
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tf->tf_x[0]= sig;
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tf->tf_x[1] = (register_t)&fp->sf_si;
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tf->tf_x[2] = (register_t)&fp->sf_uc;
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tf->tf_elr = (register_t)catcher;
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tf->tf_x[1] = (register_t)&fp->sf.sf_si;
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tf->tf_x[2] = (register_t)&fp->sf.sf_uc;
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tf->tf_x[8] = (register_t)catcher;
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tf->tf_sp = (register_t)fp;
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tf->tf_lr = (register_t)__kernel_rt_sigreturn;
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tf->tf_elr = (register_t)linux_vdso_sigcode;
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CTR3(KTR_SIG, "sendsig: return td=%p pc=%#x sp=%#x", td, tf->tf_elr,
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tf->tf_sp);
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@ -1,6 +1,6 @@
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/*
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* Linker script for 64-bit vDSO.
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* Copied from Linux kernel arch/x86/vdso/vdso-layout.lds.S
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* Copied from Linux kernel arch/arm64/kernel/vdso/vdso.lds.S
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*
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* $FreeBSD$
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*/
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@ -17,29 +17,32 @@ SECTIONS
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.gnu.version_d : { *(.gnu.version_d) }
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.gnu.version_r : { *(.gnu.version_r) }
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/DISCARD/ : {
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*(.note.GNU-stack .note.gnu.property)
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}
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.note : { *(.note.*) } :text :note
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.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
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.eh_frame : { KEEP (*(.eh_frame)) } :text
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. = ALIGN(0x100);
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.text : { *(.text*) } :text =0x90909090
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PROVIDE (__etext = .);
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PROVIDE (_etext = .);
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PROVIDE (etext = .);
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.dynamic : { *(.dynamic) } :text :dynamic
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.rodata : { *(.rodata*) } :text
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.data : {
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*(.data*)
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*(.sdata*)
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*(.got.plt) *(.got)
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*(.gnu.linkonce.d.*)
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*(.bss*)
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*(.dynbss*)
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*(.gnu.linkonce.b.*)
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*(.data*)
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}
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.altinstructions : { *(.altinstructions) }
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.altinstr_replacement : { *(.altinstr_replacement) }
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_end = .;
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PROVIDE(end = .);
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. = ALIGN(0x100);
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.text : { *(.test .text*) } :text =0x90909090
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/DISCARD/ : {
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*(.eh_frame .eh_frame_hdr)
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}
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}
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PHDRS
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@ -47,7 +50,6 @@ PHDRS
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text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
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dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
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note PT_NOTE FLAGS(4); /* PF_R */
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eh_frame_hdr PT_GNU_EH_FRAME;
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}
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/*
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@ -68,6 +70,7 @@ VERSION
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global:
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linux_platform;
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kern_timekeep_base;
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linux_vdso_sigcode;
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local: *;
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};
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}
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