"The beginning of the structure, with pretaddr, should be just below 16-byte alignment."
It is incorrect! The beginning of the structure, with pretaddr not aligned as 16-byte! On x86-64, It aligned as (16n - sizeof(void*)) because of instruction "call" ! > -----原始邮件----- > 发件人: "Richard Henderson" <richard.hender...@linaro.org> > 发送时间: 2023-05-24 13:50:43 (星期三) > 收件人: qemu-devel@nongnu.org > 抄送: fa...@mail.ustc.edu.cn, laur...@vivier.eu > 主题: Re: [PATCH] linux-user/i386: Properly align signal frame > > On 5/23/23 22:46, Richard Henderson wrote: > > The beginning of the structure, with pretaddr, should be just below > > 16-byte alignment. Disconnect fpstate from sigframe, just like the > > kernel does. > > > > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> > > --- > > linux-user/i386/signal.c | 104 +++++++++++++++++-------------- > > tests/tcg/x86_64/sigstack.c | 33 ++++++++++ > > tests/tcg/x86_64/Makefile.target | 1 + > > 3 files changed, 90 insertions(+), 48 deletions(-) > > create mode 100644 tests/tcg/x86_64/sigstack.c > > Oops, meant to add > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1648 > > r~ > > > > > diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c > > index 60fa07d6f9..c49467de78 100644 > > --- a/linux-user/i386/signal.c > > +++ b/linux-user/i386/signal.c > > @@ -191,16 +191,7 @@ struct sigframe { > > struct target_fpstate fpstate_unused; > > abi_ulong extramask[TARGET_NSIG_WORDS-1]; > > char retcode[8]; > > - > > - /* > > - * This field will be 16-byte aligned in memory. Applying QEMU_ALIGNED > > - * to it ensures that the base of the frame has an appropriate > > alignment > > - * too. > > - */ > > - struct target_fpstate fpstate QEMU_ALIGNED(8); > > }; > > -#define TARGET_SIGFRAME_FXSAVE_OFFSET ( > > \ > > - offsetof(struct sigframe, fpstate) + TARGET_FPSTATE_FXSAVE_OFFSET) > > > > struct rt_sigframe { > > abi_ulong pretcode; > > @@ -210,27 +201,21 @@ struct rt_sigframe { > > struct target_siginfo info; > > struct target_ucontext uc; > > char retcode[8]; > > - struct target_fpstate fpstate QEMU_ALIGNED(8); > > }; > > -#define TARGET_RT_SIGFRAME_FXSAVE_OFFSET ( > > \ > > - offsetof(struct rt_sigframe, fpstate) + TARGET_FPSTATE_FXSAVE_OFFSET) > > #else > > - > > struct rt_sigframe { > > abi_ulong pretcode; > > struct target_ucontext uc; > > struct target_siginfo info; > > - struct target_fpstate fpstate QEMU_ALIGNED(16); > > }; > > -#define TARGET_RT_SIGFRAME_FXSAVE_OFFSET ( > > \ > > - offsetof(struct rt_sigframe, fpstate) + TARGET_FPSTATE_FXSAVE_OFFSET) > > #endif > > > > /* > > * Set up a signal frame. > > */ > > > > -static void xsave_sigcontext(CPUX86State *env, struct > > target_fpstate_fxsave *fxsave, > > +static void xsave_sigcontext(CPUX86State *env, > > + struct target_fpstate_fxsave *fxsave, > > abi_ulong fxsave_addr) > > { > > if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) { > > @@ -266,8 +251,9 @@ static void xsave_sigcontext(CPUX86State *env, struct > > target_fpstate_fxsave *fxs > > } > > > > static void setup_sigcontext(struct target_sigcontext *sc, > > - struct target_fpstate *fpstate, CPUX86State *env, abi_ulong mask, > > - abi_ulong fpstate_addr) > > + struct target_fpstate *fpstate, > > + CPUX86State *env, abi_ulong mask, > > + abi_ulong fpstate_addr) > > { > > CPUState *cs = env_cpu(env); > > #ifndef TARGET_X86_64 > > @@ -347,10 +333,11 @@ static void setup_sigcontext(struct target_sigcontext > > *sc, > > * Determine which stack to use.. > > */ > > > > -static inline abi_ulong > > -get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t > > fxsave_offset) > > +static abi_ulong get_sigframe(struct target_sigaction *ka, CPUX86State > > *env, > > + size_t *frame_size, abi_ulong *fpsave_addr) > > { > > - unsigned long esp; > > + abi_ulong esp, orig; > > + size_t fpsave_size; > > > > /* Default to using normal stack */ > > esp = get_sp_from_cpustate(env); > > @@ -371,16 +358,23 @@ get_sigframe(struct target_sigaction *ka, CPUX86State > > *env, size_t fxsave_offset > > } > > #endif > > } > > + orig = esp; > > > > - if (!(env->features[FEAT_1_EDX] & CPUID_FXSR)) { > > - return (esp - (fxsave_offset + TARGET_FXSAVE_SIZE)) & -8ul; > > - } else if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) { > > - return ((esp - TARGET_FXSAVE_SIZE) & -16ul) - fxsave_offset; > > + if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) { > > + fpsave_size = TARGET_FXSAVE_SIZE; > > + esp = ROUND_DOWN(esp - fpsave_size, 16); > > } else { > > - size_t xstate_size = > > - xsave_area_size(env->xcr0, false) + > > TARGET_FP_XSTATE_MAGIC2_SIZE; > > - return ((esp - xstate_size) & -64ul) - fxsave_offset; > > + fpsave_size = xsave_area_size(env->xcr0, false) > > + + TARGET_FP_XSTATE_MAGIC2_SIZE; > > + esp = ROUND_DOWN(esp - fpsave_size, 64); > > } > > + *fpsave_addr = esp; > > + > > + esp = esp - *frame_size + sizeof(abi_ulong); > > + esp = ROUND_DOWN(esp, 16) - sizeof(abi_ulong); > > + > > + *frame_size = orig - esp; > > + return esp; > > } > > > > #ifndef TARGET_X86_64 > > @@ -405,26 +399,34 @@ void setup_frame(int sig, struct target_sigaction *ka, > > target_sigset_t *set, CPUX86State *env) > > { > > abi_ulong frame_addr; > > + abi_ulong fpstate_addr; > > + size_t frame_size; > > struct sigframe *frame; > > + struct target_fpstate *fpstate; > > int i; > > > > - frame_addr = get_sigframe(ka, env, TARGET_SIGFRAME_FXSAVE_OFFSET); > > + frame_size = sizeof(struct sigframe); > > + frame_addr = get_sigframe(ka, env, &frame_size, &fpstate_addr); > > trace_user_setup_frame(env, frame_addr); > > > > - if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) > > + frame = lock_user(VERIFY_WRITE, frame_addr, frame_size, false); > > + if (!frame) { > > goto give_sigsegv; > > + } > > + fpstate = (void *)frame + (fpstate_addr - frame_addr); > > > > __put_user(sig, &frame->sig); > > > > - setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0], > > - frame_addr + offsetof(struct sigframe, fpstate)); > > + setup_sigcontext(&frame->sc, fpstate, env, set->sig[0], fpstate_addr); > > > > - for(i = 1; i < TARGET_NSIG_WORDS; i++) { > > + 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. */ > > + /* > > + * 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 { > > @@ -443,11 +445,10 @@ void setup_frame(int sig, struct target_sigaction *ka, > > cpu_x86_load_seg(env, R_CS, __USER_CS); > > env->eflags &= ~TF_MASK; > > > > - unlock_user_struct(frame, frame_addr, 1); > > - > > + unlock_user(frame, frame_addr, frame_size); > > return; > > > > -give_sigsegv: > > + give_sigsegv: > > force_sigsegv(sig); > > } > > #endif > > @@ -458,17 +459,24 @@ void setup_rt_frame(int sig, struct target_sigaction > > *ka, > > target_sigset_t *set, CPUX86State *env) > > { > > abi_ulong frame_addr; > > + abi_ulong fpstate_addr; > > + size_t frame_size; > > #ifndef TARGET_X86_64 > > abi_ulong addr; > > #endif > > struct rt_sigframe *frame; > > + struct target_fpstate *fpstate; > > int i; > > > > - frame_addr = get_sigframe(ka, env, TARGET_RT_SIGFRAME_FXSAVE_OFFSET); > > + frame_size = sizeof(struct rt_sigframe); > > + frame_addr = get_sigframe(ka, env, &frame_size, &fpstate_addr); > > trace_user_setup_rt_frame(env, frame_addr); > > > > - if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) > > + frame = lock_user(VERIFY_WRITE, frame_addr, frame_size, false); > > + if (!frame) { > > goto give_sigsegv; > > + } > > + fpstate = (void *)frame + (fpstate_addr - frame_addr); > > > > /* These fields are only in rt_sigframe on 32 bit */ > > #ifndef TARGET_X86_64 > > @@ -490,10 +498,10 @@ void setup_rt_frame(int sig, struct target_sigaction > > *ka, > > } > > __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)); > > + setup_sigcontext(&frame->uc.tuc_mcontext, fpstate, env, > > + set->sig[0], fpstate_addr); > > > > - for(i = 0; i < TARGET_NSIG_WORDS; i++) { > > + for (i = 0; i < TARGET_NSIG_WORDS; i++) { > > __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]); > > } > > > > @@ -533,15 +541,15 @@ void setup_rt_frame(int sig, struct target_sigaction > > *ka, > > cpu_x86_load_seg(env, R_SS, __USER_DS); > > env->eflags &= ~TF_MASK; > > > > - unlock_user_struct(frame, frame_addr, 1); > > - > > + unlock_user(frame, frame_addr, frame_size); > > return; > > > > -give_sigsegv: > > + give_sigsegv: > > force_sigsegv(sig); > > } > > > > -static int xrstor_sigcontext(CPUX86State *env, struct > > target_fpstate_fxsave *fxsave, > > +static int xrstor_sigcontext(CPUX86State *env, > > + struct target_fpstate_fxsave *fxsave, > > abi_ulong fxsave_addr) > > { > > if (env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE) { > > diff --git a/tests/tcg/x86_64/sigstack.c b/tests/tcg/x86_64/sigstack.c > > new file mode 100644 > > index 0000000000..06cb847569 > > --- /dev/null > > +++ b/tests/tcg/x86_64/sigstack.c > > @@ -0,0 +1,33 @@ > > +#include <stdlib.h> > > +#include <assert.h> > > +#include <signal.h> > > +#include <stdint.h> > > + > > +void __attribute__((noinline)) bar(void) > > +{ > > + exit(EXIT_SUCCESS); > > +} > > + > > +void __attribute__((noinline, ms_abi)) foo(void) > > +{ > > + /* > > + * With ms_abi, there are call-saved xmm registers, which are forced > > + * to the stack around the call to sysv_abi bar(). If the signal > > + * stack frame is not properly aligned, movaps will raise #GP. > > + */ > > + bar(); > > +} > > + > > +void sighandler(int num) > > +{ > > + void* sp = __builtin_dwarf_cfa(); > > + assert((uintptr_t)sp % 16 == 0); > > + foo(); > > +} > > + > > +int main(void) > > +{ > > + signal(SIGUSR1, sighandler); > > + raise(SIGUSR1); > > + abort(); > > +} > > diff --git a/tests/tcg/x86_64/Makefile.target > > b/tests/tcg/x86_64/Makefile.target > > index e64aab1b81..d961599f64 100644 > > --- a/tests/tcg/x86_64/Makefile.target > > +++ b/tests/tcg/x86_64/Makefile.target > > @@ -13,6 +13,7 @@ X86_64_TESTS += vsyscall > > X86_64_TESTS += noexec > > X86_64_TESTS += cmpxchg > > X86_64_TESTS += adox > > +X86_64_TESTS += sigstack > > TESTS=$(MULTIARCH_TESTS) $(X86_64_TESTS) test-x86_64 > > else > > TESTS=$(MULTIARCH_TESTS) >
