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linux-user: Reorg handling for SIGSEGV 

Add stub host-signal.h for all linux-user hosts.
Add new code replacing cpu_signal_handler.
Full migration will happen one host at a time.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
master
Richard Henderson 2021-09-16 14:44:17 -07:00
parent ba0e733362
commit e6037d04c5
14 changed files with 106 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
linux-user/host/aarch64/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/arm/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/i386/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/mips/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/ppc/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/ppc64/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/riscv/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/s390/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/s390x/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/sparc/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/sparc64/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/x32/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

1
linux-user/host/x86_64/host-signal.h Normal file
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#define HOST_SIGNAL_PLACEHOLDER

109
linux-user/signal.c
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@ -19,6 +19,7 @@
#include "qemu/osdep.h"
#include "qemu/bitops.h"
#include "exec/gdbstub.h"
#include "hw/core/tcg-cpu-ops.h"
#include <sys/ucontext.h>
#include <sys/resource.h>
@ -29,6 +30,7 @@
#include "loader.h"
#include "trace.h"
#include "signal-common.h"
#include "host-signal.h"
static struct target_sigaction sigact_table[TARGET_NSIG];
@ -769,41 +771,116 @@ static inline void rewind_if_in_safe_syscall(void *puc)
}
#endif
static void host_signal_handler(int host_signum, siginfo_t *info,
void *puc)
static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
{
CPUArchState *env = thread_cpu->env_ptr;
CPUState *cpu = env_cpu(env);
TaskState *ts = cpu->opaque;
int sig;
target_siginfo_t tinfo;
ucontext_t *uc = puc;
struct emulated_sigtable *k;
int guest_sig;
#ifdef HOST_SIGNAL_PLACEHOLDER
/* the CPU emulator uses some host signals to detect exceptions,
we forward to it some signals */
if ((host_signum == SIGSEGV || host_signum == SIGBUS)
if ((host_sig == SIGSEGV || host_sig == SIGBUS)
&& info->si_code > 0) {
if (cpu_signal_handler(host_signum, info, puc))
if (cpu_signal_handler(host_sig, info, puc)) {
return;
}
}
#else
uintptr_t pc = 0;
bool sync_sig = false;
/*
* Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special
* handling wrt signal blocking and unwinding.
*/
if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) {
MMUAccessType access_type;
uintptr_t host_addr;
abi_ptr guest_addr;
bool is_write;
host_addr = (uintptr_t)info->si_addr;
/*
* Convert forcefully to guest address space: addresses outside
* reserved_va are still valid to report via SEGV_MAPERR.
*/
guest_addr = h2g_nocheck(host_addr);
pc = host_signal_pc(uc);
is_write = host_signal_write(info, uc);
access_type = adjust_signal_pc(&pc, is_write);
if (host_sig == SIGSEGV) {
const struct TCGCPUOps *tcg_ops;
if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) {
/* If this was a write to a TB protected page, restart. */
if (is_write &&
handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask,
pc, guest_addr)) {
return;
}
/*
* With reserved_va, the whole address space is PROT_NONE,
* which means that we may get ACCERR when we want MAPERR.
*/
if (page_get_flags(guest_addr) & PAGE_VALID) {
/* maperr = false; */
} else {
info->si_code = SEGV_MAPERR;
}
}
sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
tcg_ops->tlb_fill(cpu, guest_addr, 0, access_type,
MMU_USER_IDX, false, pc);
g_assert_not_reached();
} else {
sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
}
sync_sig = true;
}
#endif
/* get target signal number */
sig = host_to_target_signal(host_signum);
if (sig < 1 || sig > TARGET_NSIG)
guest_sig = host_to_target_signal(host_sig);
if (guest_sig < 1 || guest_sig > TARGET_NSIG) {
return;
trace_user_host_signal(env, host_signum, sig);
}
trace_user_host_signal(env, host_sig, guest_sig);
host_to_target_siginfo_noswap(&tinfo, info);
k = &ts->sigtab[guest_sig - 1];
k->info = tinfo;
k->pending = guest_sig;
ts->signal_pending = 1;
#ifndef HOST_SIGNAL_PLACEHOLDER
/*
* For synchronous signals, unwind the cpu state to the faulting
* insn and then exit back to the main loop so that the signal
* is delivered immediately.
*/
if (sync_sig) {
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit_restore(cpu, pc);
}
#endif
rewind_if_in_safe_syscall(puc);
host_to_target_siginfo_noswap(&tinfo, info);
k = &ts->sigtab[sig - 1];
k->info = tinfo;
k->pending = sig;
ts->signal_pending = 1;
/* Block host signals until target signal handler entered. We
/*
* Block host signals until target signal handler entered. We
* can't block SIGSEGV or SIGBUS while we're executing guest
* code in case the guest code provokes one in the window between
* now and it getting out to the main loop. Signals will be