jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
linux-user: Provide safe_syscall for ppc64
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
authored by
Richard Henderson
and committed by
Riku Voipio
4ba92cd7
c9bc3437
+115
+23
linux-user/host/ppc64/hostdep.h
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linux-user/host/ppc64/hostdep.h
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#ifndef QEMU_HOSTDEP_H
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#define QEMU_HOSTDEP_H
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/* We have a safe-syscall.inc.S */
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#define HAVE_SAFE_SYSCALL
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#ifndef __ASSEMBLER__
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/* These are defined by the safe-syscall.inc.S file */
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extern char safe_syscall_start[];
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extern char safe_syscall_end[];
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/* Adjust the signal context to rewind out of safe-syscall if we're in it */
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static inline void rewind_if_in_safe_syscall(void *puc)
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{
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struct ucontext *uc = puc;
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unsigned long *pcreg = &uc->uc_mcontext.gp_regs[PT_NIP];
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if (*pcreg > (uintptr_t)safe_syscall_start
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&& *pcreg < (uintptr_t)safe_syscall_end) {
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*pcreg = (uintptr_t)safe_syscall_start;
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}
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}
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#endif /* __ASSEMBLER__ */
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#endif
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linux-user/host/ppc64/safe-syscall.inc.S
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linux-user/host/ppc64/safe-syscall.inc.S
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/*
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* safe-syscall.inc.S : host-specific assembly fragment
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* to handle signals occurring at the same time as system calls.
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* This is intended to be included by linux-user/safe-syscall.S
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*
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* Written by Richard Henderson <rth@twiddle.net>
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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.global safe_syscall_base
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.global safe_syscall_start
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.global safe_syscall_end
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.type safe_syscall_base, @function
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.text
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/* This is the entry point for making a system call. The calling
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* convention here is that of a C varargs function with the
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* first argument an 'int *' to the signal_pending flag, the
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* second one the system call number (as a 'long'), and all further
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* arguments being syscall arguments (also 'long').
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* We return a long which is the syscall's return value, which
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* may be negative-errno on failure. Conversion to the
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* -1-and-errno-set convention is done by the calling wrapper.
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*/
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#if _CALL_ELF == 2
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safe_syscall_base:
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.cfi_startproc
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.localentry safe_syscall_base,0
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#else
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.section ".opd","aw"
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.align 3
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safe_syscall_base:
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.quad .L.safe_syscall_base,.TOC.@tocbase,0
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.previous
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.L.safe_syscall_base:
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.cfi_startproc
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#endif
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/* We enter with r3 == *signal_pending
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* r4 == syscall number
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* r5 ... r10 == syscall arguments
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* and return the result in r3
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* and the syscall instruction needs
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* r0 == syscall number
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* r3 ... r8 == syscall arguments
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* and returns the result in r3
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* Shuffle everything around appropriately.
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*/
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mr 11, 3 /* signal_pending */
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mr 0, 4 /* syscall number */
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mr 3, 5 /* syscall arguments */
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mr 4, 6
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mr 5, 7
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mr 6, 8
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mr 7, 9
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mr 8, 10
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/* This next sequence of code works in conjunction with the
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* rewind_if_safe_syscall_function(). If a signal is taken
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* and the interrupted PC is anywhere between 'safe_syscall_start'
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* and 'safe_syscall_end' then we rewind it to 'safe_syscall_start'.
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* The code sequence must therefore be able to cope with this, and
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* the syscall instruction must be the final one in the sequence.
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*/
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safe_syscall_start:
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/* if signal_pending is non-zero, don't do the call */
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lwz 12, 0(11)
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cmpwi 0, 12, 0
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bne- 0f
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sc
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safe_syscall_end:
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/* code path when we did execute the syscall */
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bnslr+
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/* syscall failed; return negative errno */
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neg 3, 3
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blr
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/* code path when we didn't execute the syscall */
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0: addi 3, 0, -TARGET_ERESTARTSYS
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blr
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.cfi_endproc
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#if _CALL_ELF == 2
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.size safe_syscall_base, .-safe_syscall_base
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#else
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.size safe_syscall_base, .-.L.safe_syscall_base
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.size .L.safe_syscall_base, .-.L.safe_syscall_base
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#endif