From 2796f290b5469a7f6749ea119a48bc17f489effd Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 6 Oct 2022 13:31:06 +0200 Subject: [PATCH] linux-user: i386/signal: support FXSAVE fpstate on 32-bit emulation Linux can use FXSAVE to save/restore XMM registers even on 32-bit systems. This requires some care in order to keep the FXSAVE area aligned to 16 bytes; for this reason, get_sigframe is changed to pass the offset into the FXSAVE area rather than the full frame size. Reviewed-by: Richard Henderson Signed-off-by: Paolo Bonzini --- linux-user/i386/signal.c | 129 +++++++++++++++++++++++---------------- 1 file changed, 77 insertions(+), 52 deletions(-) diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c index 76317a3d16..58b11be116 100644 --- a/linux-user/i386/signal.c +++ b/linux-user/i386/signal.c @@ -39,29 +39,7 @@ 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 { +struct target_fpstate_fxsave { /* FXSAVE format */ uint16_t cw; uint16_t sw; @@ -75,11 +53,36 @@ struct target_fpstate_64 { uint32_t xmm_space[64]; uint32_t reserved[24]; }; +#define TARGET_FXSAVE_SIZE sizeof(struct target_fpstate_fxsave) +QEMU_BUILD_BUG_ON(TARGET_FXSAVE_SIZE != 512); + +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 */ + struct target_fpstate_fxsave fxsave; +}; + +/* + * For simplicity, setup_frame aligns struct target_fpstate_32 to + * 16 bytes, so ensure that the FXSAVE area is also aligned. + */ +QEMU_BUILD_BUG_ON(offsetof(struct target_fpstate_32, fxsave) & 15); #ifndef TARGET_X86_64 # define target_fpstate target_fpstate_32 +# define TARGET_FPSTATE_FXSAVE_OFFSET offsetof(struct target_fpstate_32, fxsave) #else -# define target_fpstate target_fpstate_64 +# define target_fpstate target_fpstate_fxsave +# define TARGET_FPSTATE_FXSAVE_OFFSET 0 #endif struct target_sigcontext_32 { @@ -172,8 +175,16 @@ struct sigframe { struct target_fpstate fpstate_unused; abi_ulong extramask[TARGET_NSIG_WORDS-1]; char retcode[8]; - struct target_fpstate fpstate; + + /* + * 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; @@ -183,25 +194,35 @@ struct rt_sigframe { struct target_siginfo info; struct target_ucontext uc; char retcode[8]; - struct target_fpstate fpstate; + 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; + 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. */ -/* XXX: save x87 state */ +static void fxsave_sigcontext(CPUX86State *env, struct target_fpstate_fxsave *fxsave, + abi_ulong fxsave_addr) +{ + /* fxsave_addr must be 16 byte aligned for fxsave */ + assert(!(fxsave_addr & 0xf)); + + cpu_x86_fxsave(env, fxsave_addr); +} + static void setup_sigcontext(struct target_sigcontext *sc, struct target_fpstate *fpstate, CPUX86State *env, abi_ulong mask, abi_ulong fpstate_addr) @@ -233,13 +254,14 @@ static void setup_sigcontext(struct target_sigcontext *sc, cpu_x86_fsave(env, fpstate_addr, 1); fpstate->status = fpstate->sw; - magic = 0xffff; + if (!(env->features[FEAT_1_EDX] & CPUID_FXSR)) { + magic = 0xffff; + } else { + fxsave_sigcontext(env, &fpstate->fxsave, + fpstate_addr + TARGET_FPSTATE_FXSAVE_OFFSET); + magic = 0; + } __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); @@ -269,15 +291,14 @@ static void setup_sigcontext(struct target_sigcontext *sc, __put_user((uint16_t)0, &sc->fs); __put_user(env->segs[R_SS].selector, &sc->ss); + fxsave_sigcontext(env, fpstate, fpstate_addr); +#endif + + __put_user(fpstate_addr, &sc->fpstate); + + /* non-iBCS2 extensions.. */ __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 } /* @@ -285,7 +306,7 @@ static void setup_sigcontext(struct target_sigcontext *sc, */ static inline abi_ulong -get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size) +get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t fxsave_offset) { unsigned long esp; @@ -309,11 +330,11 @@ get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size) #endif } -#ifndef TARGET_X86_64 - return (esp - frame_size) & -8ul; -#else - return ((esp - frame_size) & (~15ul)) - 8; -#endif + if (!(env->features[FEAT_1_EDX] & CPUID_FXSR)) { + return (esp - (fxsave_offset + TARGET_FXSAVE_SIZE)) & -8ul; + } else { + return ((esp - TARGET_FXSAVE_SIZE) & -16ul) - fxsave_offset; + } } #ifndef TARGET_X86_64 @@ -341,7 +362,7 @@ void setup_frame(int sig, struct target_sigaction *ka, struct sigframe *frame; int i; - frame_addr = get_sigframe(ka, env, sizeof(*frame)); + frame_addr = get_sigframe(ka, env, TARGET_SIGFRAME_FXSAVE_OFFSET); trace_user_setup_frame(env, frame_addr); if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) @@ -397,7 +418,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka, struct rt_sigframe *frame; int i; - frame_addr = get_sigframe(ka, env, sizeof(*frame)); + frame_addr = get_sigframe(ka, env, TARGET_RT_SIGFRAME_FXSAVE_OFFSET); trace_user_setup_rt_frame(env, frame_addr); if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) @@ -529,7 +550,11 @@ restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc) goto badframe; } #ifndef TARGET_X86_64 - cpu_x86_frstor(env, fpstate_addr, 1); + if (!(env->features[FEAT_1_EDX] & CPUID_FXSR)) { + cpu_x86_frstor(env, fpstate_addr, 1); + } else { + cpu_x86_fxrstor(env, fpstate_addr + TARGET_FPSTATE_FXSAVE_OFFSET); + } #else cpu_x86_fxrstor(env, fpstate_addr); #endif