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qemu/linux-user/i386/signal.c
Richard Henderson db20554159 linux-user/x86_64: Raise SIGSEGV if SA_RESTORER not set 
This has been a fixme for some time.  The effect of
returning -EFAULT from the kernel code is to raise SIGSEGV.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-12-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-10-01 12:03:48 +02:00

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/*
* Emulation of Linux signals
*
* Copyright (c) 2003 Fabrice Bellard
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu.h"
#include "user-internals.h"
#include "signal-common.h"
#include "linux-user/trace.h"
/* from the Linux kernel - /arch/x86/include/uapi/asm/sigcontext.h */
struct target_fpreg {
uint16_t significand[4];
uint16_t exponent;
};
struct target_fpxreg {
uint16_t significand[4];
uint16_t exponent;
uint16_t padding[3];
};
struct target_xmmreg {
uint32_t element[4];
};
struct target_fpstate_32 {
/* Regular FPU environment */
uint32_t cw;
uint32_t sw;
uint32_t tag;
uint32_t ipoff;
uint32_t cssel;
uint32_t dataoff;
uint32_t datasel;
struct target_fpreg st[8];
uint16_t status;
uint16_t magic; /* 0xffff = regular FPU data only */
/* FXSR FPU environment */
uint32_t _fxsr_env[6]; /* FXSR FPU env is ignored */
uint32_t mxcsr;
uint32_t reserved;
struct target_fpxreg fxsr_st[8]; /* FXSR FPU reg data is ignored */
struct target_xmmreg xmm[8];
uint32_t padding[56];
};
struct target_fpstate_64 {
/* FXSAVE format */
uint16_t cw;
uint16_t sw;
uint16_t twd;
uint16_t fop;
uint64_t rip;
uint64_t rdp;
uint32_t mxcsr;
uint32_t mxcsr_mask;
uint32_t st_space[32];
uint32_t xmm_space[64];
uint32_t reserved[24];
};
#ifndef TARGET_X86_64
# define target_fpstate target_fpstate_32
#else
# define target_fpstate target_fpstate_64
#endif
struct target_sigcontext_32 {
uint16_t gs, __gsh;
uint16_t fs, __fsh;
uint16_t es, __esh;
uint16_t ds, __dsh;
uint32_t edi;
uint32_t esi;
uint32_t ebp;
uint32_t esp;
uint32_t ebx;
uint32_t edx;
uint32_t ecx;
uint32_t eax;
uint32_t trapno;
uint32_t err;
uint32_t eip;
uint16_t cs, __csh;
uint32_t eflags;
uint32_t esp_at_signal;
uint16_t ss, __ssh;
uint32_t fpstate; /* pointer */
uint32_t oldmask;
uint32_t cr2;
};
struct target_sigcontext_64 {
uint64_t r8;
uint64_t r9;
uint64_t r10;
uint64_t r11;
uint64_t r12;
uint64_t r13;
uint64_t r14;
uint64_t r15;
uint64_t rdi;
uint64_t rsi;
uint64_t rbp;
uint64_t rbx;
uint64_t rdx;
uint64_t rax;
uint64_t rcx;
uint64_t rsp;
uint64_t rip;
uint64_t eflags;
uint16_t cs;
uint16_t gs;
uint16_t fs;
uint16_t ss;
uint64_t err;
uint64_t trapno;
uint64_t oldmask;
uint64_t cr2;
uint64_t fpstate; /* pointer */
uint64_t padding[8];
};
#ifndef TARGET_X86_64
# define target_sigcontext target_sigcontext_32
#else
# define target_sigcontext target_sigcontext_64
#endif
/* see Linux/include/uapi/asm-generic/ucontext.h */
struct target_ucontext {
abi_ulong tuc_flags;
abi_ulong tuc_link;
target_stack_t tuc_stack;
struct target_sigcontext tuc_mcontext;
target_sigset_t tuc_sigmask; /* mask last for extensibility */
};
#ifndef TARGET_X86_64
struct sigframe {
abi_ulong pretcode;
int sig;
struct target_sigcontext sc;
struct target_fpstate fpstate;
abi_ulong extramask[TARGET_NSIG_WORDS-1];
char retcode[8];
};
struct rt_sigframe {
abi_ulong pretcode;
int sig;
abi_ulong pinfo;
abi_ulong puc;
struct target_siginfo info;
struct target_ucontext uc;
struct target_fpstate fpstate;
char retcode[8];
};
#else
struct rt_sigframe {
abi_ulong pretcode;
struct target_ucontext uc;
struct target_siginfo info;
struct target_fpstate fpstate;
};
#endif
/*
* Set up a signal frame.
*/
/* XXX: save x87 state */
static void setup_sigcontext(struct target_sigcontext *sc,
struct target_fpstate *fpstate, CPUX86State *env, abi_ulong mask,
abi_ulong fpstate_addr)
{
CPUState *cs = env_cpu(env);
#ifndef TARGET_X86_64
uint16_t magic;
/* already locked in setup_frame() */
__put_user(env->segs[R_GS].selector, (unsigned int *)&sc->gs);
__put_user(env->segs[R_FS].selector, (unsigned int *)&sc->fs);
__put_user(env->segs[R_ES].selector, (unsigned int *)&sc->es);
__put_user(env->segs[R_DS].selector, (unsigned int *)&sc->ds);
__put_user(env->regs[R_EDI], &sc->edi);
__put_user(env->regs[R_ESI], &sc->esi);
__put_user(env->regs[R_EBP], &sc->ebp);
__put_user(env->regs[R_ESP], &sc->esp);
__put_user(env->regs[R_EBX], &sc->ebx);
__put_user(env->regs[R_EDX], &sc->edx);
__put_user(env->regs[R_ECX], &sc->ecx);
__put_user(env->regs[R_EAX], &sc->eax);
__put_user(cs->exception_index, &sc->trapno);
__put_user(env->error_code, &sc->err);
__put_user(env->eip, &sc->eip);
__put_user(env->segs[R_CS].selector, (unsigned int *)&sc->cs);
__put_user(env->eflags, &sc->eflags);
__put_user(env->regs[R_ESP], &sc->esp_at_signal);
__put_user(env->segs[R_SS].selector, (unsigned int *)&sc->ss);
cpu_x86_fsave(env, fpstate_addr, 1);
fpstate->status = fpstate->sw;
magic = 0xffff;
__put_user(magic, &fpstate->magic);
__put_user(fpstate_addr, &sc->fpstate);
/* non-iBCS2 extensions.. */
__put_user(mask, &sc->oldmask);
__put_user(env->cr[2], &sc->cr2);
#else
__put_user(env->regs[R_EDI], &sc->rdi);
__put_user(env->regs[R_ESI], &sc->rsi);
__put_user(env->regs[R_EBP], &sc->rbp);
__put_user(env->regs[R_ESP], &sc->rsp);
__put_user(env->regs[R_EBX], &sc->rbx);
__put_user(env->regs[R_EDX], &sc->rdx);
__put_user(env->regs[R_ECX], &sc->rcx);
__put_user(env->regs[R_EAX], &sc->rax);
__put_user(env->regs[8], &sc->r8);
__put_user(env->regs[9], &sc->r9);
__put_user(env->regs[10], &sc->r10);
__put_user(env->regs[11], &sc->r11);
__put_user(env->regs[12], &sc->r12);
__put_user(env->regs[13], &sc->r13);
__put_user(env->regs[14], &sc->r14);
__put_user(env->regs[15], &sc->r15);
__put_user(cs->exception_index, &sc->trapno);
__put_user(env->error_code, &sc->err);
__put_user(env->eip, &sc->rip);
__put_user(env->eflags, &sc->eflags);
__put_user(env->segs[R_CS].selector, &sc->cs);
__put_user((uint16_t)0, &sc->gs);
__put_user((uint16_t)0, &sc->fs);
__put_user(env->segs[R_SS].selector, &sc->ss);
__put_user(mask, &sc->oldmask);
__put_user(env->cr[2], &sc->cr2);
/* fpstate_addr must be 16 byte aligned for fxsave */
assert(!(fpstate_addr & 0xf));
cpu_x86_fxsave(env, fpstate_addr);
__put_user(fpstate_addr, &sc->fpstate);
#endif
}
/*
* Determine which stack to use..
*/
static inline abi_ulong
get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size)
{
unsigned long esp;
/* Default to using normal stack */
esp = get_sp_from_cpustate(env);
#ifdef TARGET_X86_64
esp -= 128; /* this is the redzone */
#endif
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa_flags & TARGET_SA_ONSTACK) {
esp = target_sigsp(esp, ka);
} else {
#ifndef TARGET_X86_64
/* This is the legacy signal stack switching. */
if ((env->segs[R_SS].selector & 0xffff) != __USER_DS &&
!(ka->sa_flags & TARGET_SA_RESTORER) &&
ka->sa_restorer) {
esp = (unsigned long) ka->sa_restorer;
}
#endif
}
#ifndef TARGET_X86_64
return (esp - frame_size) & -8ul;
#else
return ((esp - frame_size) & (~15ul)) - 8;
#endif
}
#ifndef TARGET_X86_64
static void install_sigtramp(void *tramp)
{
/* This is popl %eax ; movl $syscall,%eax ; int $0x80 */
__put_user(0xb858, (uint16_t *)(tramp + 0));
__put_user(TARGET_NR_sigreturn, (int32_t *)(tramp + 2));
__put_user(0x80cd, (uint16_t *)(tramp + 6));
}
static void install_rt_sigtramp(void *tramp)
{
/* This is movl $syscall,%eax ; int $0x80 */
__put_user(0xb8, (uint8_t *)(tramp + 0));
__put_user(TARGET_NR_rt_sigreturn, (int32_t *)(tramp + 1));
__put_user(0x80cd, (uint16_t *)(tramp + 5));
}
/* compare linux/arch/i386/kernel/signal.c:setup_frame() */
void setup_frame(int sig, struct target_sigaction *ka,
target_sigset_t *set, CPUX86State *env)
{
abi_ulong frame_addr;
struct sigframe *frame;
int i;
frame_addr = get_sigframe(ka, env, sizeof(*frame));
trace_user_setup_frame(env, frame_addr);
if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
goto give_sigsegv;
__put_user(sig, &frame->sig);
setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0],
frame_addr + offsetof(struct sigframe, fpstate));
for(i = 1; i < TARGET_NSIG_WORDS; i++) {
__put_user(set->sig[i], &frame->extramask[i - 1]);
}
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->sa_flags & TARGET_SA_RESTORER) {
__put_user(ka->sa_restorer, &frame->pretcode);
} else {
/* This is no longer used, but is retained for ABI compatibility. */
install_sigtramp(frame->retcode);
__put_user(default_sigreturn, &frame->pretcode);
}
/* Set up registers for signal handler */
env->regs[R_ESP] = frame_addr;
env->eip = ka->_sa_handler;
cpu_x86_load_seg(env, R_DS, __USER_DS);
cpu_x86_load_seg(env, R_ES, __USER_DS);
cpu_x86_load_seg(env, R_SS, __USER_DS);
cpu_x86_load_seg(env, R_CS, __USER_CS);
env->eflags &= ~TF_MASK;
unlock_user_struct(frame, frame_addr, 1);
return;
give_sigsegv:
force_sigsegv(sig);
}
#endif
/* compare linux/arch/x86/kernel/signal.c:setup_rt_frame() */
void setup_rt_frame(int sig, struct target_sigaction *ka,
target_siginfo_t *info,
target_sigset_t *set, CPUX86State *env)
{
abi_ulong frame_addr;
#ifndef TARGET_X86_64
abi_ulong addr;
#endif
struct rt_sigframe *frame;
int i;
frame_addr = get_sigframe(ka, env, sizeof(*frame));
trace_user_setup_rt_frame(env, frame_addr);
if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
goto give_sigsegv;
/* These fields are only in rt_sigframe on 32 bit */
#ifndef TARGET_X86_64
__put_user(sig, &frame->sig);
addr = frame_addr + offsetof(struct rt_sigframe, info);
__put_user(addr, &frame->pinfo);
addr = frame_addr + offsetof(struct rt_sigframe, uc);
__put_user(addr, &frame->puc);
#endif
if (ka->sa_flags & TARGET_SA_SIGINFO) {
tswap_siginfo(&frame->info, info);
}
/* Create the ucontext. */
__put_user(0, &frame->uc.tuc_flags);
__put_user(0, &frame->uc.tuc_link);
target_save_altstack(&frame->uc.tuc_stack, env);
setup_sigcontext(&frame->uc.tuc_mcontext, &frame->fpstate, env,
set->sig[0], frame_addr + offsetof(struct rt_sigframe, fpstate));
for(i = 0; i < TARGET_NSIG_WORDS; i++) {
__put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
}
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->sa_flags & TARGET_SA_RESTORER) {
__put_user(ka->sa_restorer, &frame->pretcode);
} else {
#ifdef TARGET_X86_64
/* For x86_64, SA_RESTORER is required ABI. */
goto give_sigsegv;
#else
/* This is no longer used, but is retained for ABI compatibility. */
install_rt_sigtramp(frame->retcode);
__put_user(default_rt_sigreturn, &frame->pretcode);
#endif
}
/* Set up registers for signal handler */
env->regs[R_ESP] = frame_addr;
env->eip = ka->_sa_handler;
#ifndef TARGET_X86_64
env->regs[R_EAX] = sig;
env->regs[R_EDX] = frame_addr + offsetof(struct rt_sigframe, info);
env->regs[R_ECX] = frame_addr + offsetof(struct rt_sigframe, uc);
#else
env->regs[R_EAX] = 0;
env->regs[R_EDI] = sig;
env->regs[R_ESI] = frame_addr + offsetof(struct rt_sigframe, info);
env->regs[R_EDX] = frame_addr + offsetof(struct rt_sigframe, uc);
#endif
cpu_x86_load_seg(env, R_DS, __USER_DS);
cpu_x86_load_seg(env, R_ES, __USER_DS);
cpu_x86_load_seg(env, R_CS, __USER_CS);
cpu_x86_load_seg(env, R_SS, __USER_DS);
env->eflags &= ~TF_MASK;
unlock_user_struct(frame, frame_addr, 1);
return;
give_sigsegv:
force_sigsegv(sig);
}
static int
restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc)
{
unsigned int err = 0;
abi_ulong fpstate_addr;
unsigned int tmpflags;
#ifndef TARGET_X86_64
cpu_x86_load_seg(env, R_GS, tswap16(sc->gs));
cpu_x86_load_seg(env, R_FS, tswap16(sc->fs));
cpu_x86_load_seg(env, R_ES, tswap16(sc->es));
cpu_x86_load_seg(env, R_DS, tswap16(sc->ds));
env->regs[R_EDI] = tswapl(sc->edi);
env->regs[R_ESI] = tswapl(sc->esi);
env->regs[R_EBP] = tswapl(sc->ebp);
env->regs[R_ESP] = tswapl(sc->esp);
env->regs[R_EBX] = tswapl(sc->ebx);
env->regs[R_EDX] = tswapl(sc->edx);
env->regs[R_ECX] = tswapl(sc->ecx);
env->regs[R_EAX] = tswapl(sc->eax);
env->eip = tswapl(sc->eip);
#else
env->regs[8] = tswapl(sc->r8);
env->regs[9] = tswapl(sc->r9);
env->regs[10] = tswapl(sc->r10);
env->regs[11] = tswapl(sc->r11);
env->regs[12] = tswapl(sc->r12);
env->regs[13] = tswapl(sc->r13);
env->regs[14] = tswapl(sc->r14);
env->regs[15] = tswapl(sc->r15);
env->regs[R_EDI] = tswapl(sc->rdi);
env->regs[R_ESI] = tswapl(sc->rsi);
env->regs[R_EBP] = tswapl(sc->rbp);
env->regs[R_EBX] = tswapl(sc->rbx);
env->regs[R_EDX] = tswapl(sc->rdx);
env->regs[R_EAX] = tswapl(sc->rax);
env->regs[R_ECX] = tswapl(sc->rcx);
env->regs[R_ESP] = tswapl(sc->rsp);
env->eip = tswapl(sc->rip);
#endif
cpu_x86_load_seg(env, R_CS, lduw_p(&sc->cs) | 3);
cpu_x86_load_seg(env, R_SS, lduw_p(&sc->ss) | 3);
tmpflags = tswapl(sc->eflags);
env->eflags = (env->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
// regs->orig_eax = -1; /* disable syscall checks */
fpstate_addr = tswapl(sc->fpstate);
if (fpstate_addr != 0) {
if (!access_ok(env_cpu(env), VERIFY_READ, fpstate_addr,
sizeof(struct target_fpstate))) {
goto badframe;
}
#ifndef TARGET_X86_64
cpu_x86_frstor(env, fpstate_addr, 1);
#else
cpu_x86_fxrstor(env, fpstate_addr);
#endif
}
return err;
badframe:
return 1;
}
/* Note: there is no sigreturn on x86_64, there is only rt_sigreturn */
#ifndef TARGET_X86_64
long do_sigreturn(CPUX86State *env)
{
struct sigframe *frame;
abi_ulong frame_addr = env->regs[R_ESP] - 8;
target_sigset_t target_set;
sigset_t set;
int i;
trace_user_do_sigreturn(env, frame_addr);
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
/* set blocked signals */
__get_user(target_set.sig[0], &frame->sc.oldmask);
for(i = 1; i < TARGET_NSIG_WORDS; i++) {
__get_user(target_set.sig[i], &frame->extramask[i - 1]);
}
target_to_host_sigset_internal(&set, &target_set);
set_sigmask(&set);
/* restore registers */
if (restore_sigcontext(env, &frame->sc))
goto badframe;
unlock_user_struct(frame, frame_addr, 0);
return -TARGET_QEMU_ESIGRETURN;
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
return -TARGET_QEMU_ESIGRETURN;
}
#endif
long do_rt_sigreturn(CPUX86State *env)
{
abi_ulong frame_addr;
struct rt_sigframe *frame;
sigset_t set;
frame_addr = env->regs[R_ESP] - sizeof(abi_ulong);
trace_user_do_rt_sigreturn(env, frame_addr);
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
set_sigmask(&set);
if (restore_sigcontext(env, &frame->uc.tuc_mcontext)) {
goto badframe;
}
target_restore_altstack(&frame->uc.tuc_stack, env);
unlock_user_struct(frame, frame_addr, 0);
return -TARGET_QEMU_ESIGRETURN;
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
return -TARGET_QEMU_ESIGRETURN;
}
#ifndef TARGET_X86_64
void setup_sigtramp(abi_ulong sigtramp_page)
{
uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0);
assert(tramp != NULL);
default_sigreturn = sigtramp_page;
install_sigtramp(tramp);
default_rt_sigreturn = sigtramp_page + 8;
install_rt_sigtramp(tramp + 8);
unlock_user(tramp, sigtramp_page, 2 * 8);
}
#endif
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