diff options
author | Benjamin Berg <[email protected]> | 2024-10-23 11:41:20 +0200 |
---|---|---|
committer | Johannes Berg <[email protected]> | 2024-10-23 12:13:16 +0200 |
commit | 3f17fed2149192c7d3b76a45a6a87b4ff22cd586 (patch) | |
tree | 6c76ac37c9db356076f5540230b84635a8b90efd /arch/x86/um/signal.c | |
parent | 0b8b2668f9981c1fefc2ef892bd915288ef01f33 (diff) |
um: switch to regset API and depend on XSTATE
The PTRACE_GETREGSET API has now existed since Linux 2.6.33. The XSAVE
CPU feature should also be sufficiently common to be able to rely on it.
With this, define our internal FP state to be the hosts XSAVE data. Add
discovery for the hosts XSAVE size and place the FP registers at the end
of task_struct so that we can adjust the size at runtime.
Next we can implement the regset API on top and update the signal
handling as well as ptrace APIs to use them. Also switch coredump
creation to use the regset API and finally set HAVE_ARCH_TRACEHOOK.
This considerably improves the signal frames. Previously they might not
have contained all the registers (i386) and also did not have the
sizes and magic values set to the correct values to permit userspace to
decode the frame.
As a side effect, this will permit UML to run on hosts with newer CPU
extensions (such as AMX) that need even more register state.
Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>
Diffstat (limited to 'arch/x86/um/signal.c')
-rw-r--r-- | arch/x86/um/signal.c | 322 |
1 files changed, 101 insertions, 221 deletions
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c index fa78c74e00cb..94b2b2bbae31 100644 --- a/arch/x86/um/signal.c +++ b/arch/x86/um/signal.c @@ -16,145 +16,24 @@ #include <registers.h> #include <skas.h> -#ifdef CONFIG_X86_32 - -/* - * FPU tag word conversions. - */ - -static inline unsigned short twd_i387_to_fxsr(unsigned short twd) -{ - unsigned int tmp; /* to avoid 16 bit prefixes in the code */ - - /* Transform each pair of bits into 01 (valid) or 00 (empty) */ - tmp = ~twd; - tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */ - /* and move the valid bits to the lower byte. */ - tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */ - tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */ - tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */ - return tmp; -} - -static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave) -{ - struct _fpxreg *st = NULL; - unsigned long twd = (unsigned long) fxsave->twd; - unsigned long tag; - unsigned long ret = 0xffff0000; - int i; - -#define FPREG_ADDR(f, n) ((char *)&(f)->st_space + (n) * 16) - - for (i = 0; i < 8; i++) { - if (twd & 0x1) { - st = (struct _fpxreg *) FPREG_ADDR(fxsave, i); - - switch (st->exponent & 0x7fff) { - case 0x7fff: - tag = 2; /* Special */ - break; - case 0x0000: - if ( !st->significand[0] && - !st->significand[1] && - !st->significand[2] && - !st->significand[3] ) { - tag = 1; /* Zero */ - } else { - tag = 2; /* Special */ - } - break; - default: - if (st->significand[3] & 0x8000) { - tag = 0; /* Valid */ - } else { - tag = 2; /* Special */ - } - break; - } - } else { - tag = 3; /* Empty */ - } - ret |= (tag << (2 * i)); - twd = twd >> 1; - } - return ret; -} - -static int convert_fxsr_to_user(struct _fpstate __user *buf, - struct user_fxsr_struct *fxsave) -{ - unsigned long env[7]; - struct _fpreg __user *to; - struct _fpxreg *from; - int i; - - env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul; - env[1] = (unsigned long)fxsave->swd | 0xffff0000ul; - env[2] = twd_fxsr_to_i387(fxsave); - env[3] = fxsave->fip; - env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16); - env[5] = fxsave->foo; - env[6] = fxsave->fos; - - if (__copy_to_user(buf, env, 7 * sizeof(unsigned long))) - return 1; - - to = &buf->_st[0]; - from = (struct _fpxreg *) &fxsave->st_space[0]; - for (i = 0; i < 8; i++, to++, from++) { - unsigned long __user *t = (unsigned long __user *)to; - unsigned long *f = (unsigned long *)from; - - if (__put_user(*f, t) || - __put_user(*(f + 1), t + 1) || - __put_user(from->exponent, &to->exponent)) - return 1; - } - return 0; -} - -static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave, - struct _fpstate __user *buf) -{ - unsigned long env[7]; - struct _fpxreg *to; - struct _fpreg __user *from; - int i; - - if (copy_from_user( env, buf, 7 * sizeof(long))) - return 1; - - fxsave->cwd = (unsigned short)(env[0] & 0xffff); - fxsave->swd = (unsigned short)(env[1] & 0xffff); - fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff)); - fxsave->fip = env[3]; - fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16); - fxsave->fcs = (env[4] & 0xffff); - fxsave->foo = env[5]; - fxsave->fos = env[6]; - - to = (struct _fpxreg *) &fxsave->st_space[0]; - from = &buf->_st[0]; - for (i = 0; i < 8; i++, to++, from++) { - unsigned long *t = (unsigned long *)to; - unsigned long __user *f = (unsigned long __user *)from; - - if (__get_user(*t, f) || - __get_user(*(t + 1), f + 1) || - __get_user(to->exponent, &from->exponent)) - return 1; - } - return 0; -} - -extern int have_fpx_regs; +#include <linux/regset.h> +#include <asm/sigframe.h> +#ifdef CONFIG_X86_32 +struct _xstate_64 { + struct _fpstate_64 fpstate; + struct _header xstate_hdr; + struct _ymmh_state ymmh; + /* New processor state extensions go here: */ +}; +#else +#define _xstate_64 _xstate #endif static int copy_sc_from_user(struct pt_regs *regs, struct sigcontext __user *from) { + struct _xstate_64 __user *from_fp64; struct sigcontext sc; int err; @@ -203,31 +82,26 @@ static int copy_sc_from_user(struct pt_regs *regs, #undef GETREG #ifdef CONFIG_X86_32 - if (have_fpx_regs) { - struct user_fxsr_struct *fpx; - fpx = (void *)®s->regs.fp; - - err = convert_fxsr_from_user(fpx, (void *)sc.fpstate); - if (err) - return 1; - } else { - BUILD_BUG_ON(sizeof(regs->regs.fp) > sizeof(struct _fpstate)); - err = copy_from_user(regs->regs.fp, (void *)sc.fpstate, - sizeof(regs->regs.fp)); - if (err) - return 1; - } + from_fp64 = ((void *)sc.fpstate) + offsetof(struct _fpstate_32, _fxsr_env); #else - { - /* FIXME: Save/restore extended state (past the 16 YMM regs) */ - BUILD_BUG_ON(sizeof(regs->regs.fp) < sizeof(struct _xstate)); + from_fp64 = (void *)sc.fpstate; +#endif - err = copy_from_user(regs->regs.fp, (void *)sc.fpstate, - sizeof(struct _xstate)); - if (err) - return 1; - } + err = copy_from_user(regs->regs.fp, from_fp64, host_fp_size); + if (err) + return 1; + +#ifdef CONFIG_X86_32 + /* Data is duplicated and this copy is the important one */ + err = copy_regset_from_user(current, + task_user_regset_view(current), + REGSET_FP_LEGACY, 0, + sizeof(struct user_i387_struct), + (void *)sc.fpstate); + if (err < 0) + return err; #endif + return 0; } @@ -235,6 +109,7 @@ static int copy_sc_to_user(struct sigcontext __user *to, struct _xstate __user *to_fp, struct pt_regs *regs, unsigned long mask) { + struct _xstate_64 __user *to_fp64; struct sigcontext sc; struct faultinfo * fi = ¤t->thread.arch.faultinfo; int err; @@ -286,36 +161,44 @@ static int copy_sc_to_user(struct sigcontext __user *to, return 1; #ifdef CONFIG_X86_32 - if (have_fpx_regs) { - struct user_fxsr_struct *fpx; - - fpx = (void *)®s->regs.fp; + err = copy_regset_to_user(current, + task_user_regset_view(current), + REGSET_FP_LEGACY, 0, + sizeof(struct _fpstate_32), to_fp); + if (err < 0) + return err; - err = convert_fxsr_to_user(&to_fp->fpstate, fpx); - if (err) - return 1; + __put_user(X86_FXSR_MAGIC, &to_fp->fpstate.magic); - err |= __put_user(fpx->swd, &to_fp->fpstate.status); - err |= __put_user(X86_FXSR_MAGIC, &to_fp->fpstate.magic); - if (err) - return 1; - - } else { - if (copy_to_user(to_fp, regs->regs.fp, sizeof(regs->regs.fp))) - return 1; - - /* Need to fill in the sw_reserved bits ... */ - BUILD_BUG_ON(offsetof(typeof(*to_fp), - fpstate.sw_reserved.magic1) >= - sizeof(struct _fpstate)); - __put_user(0, &to_fp->fpstate.sw_reserved.magic1); - __put_user(sizeof(struct _fpstate), - &to_fp->fpstate.sw_reserved.extended_size); - } + BUILD_BUG_ON(offsetof(struct _xstate, xstate_hdr) != + offsetof(struct _xstate_64, xstate_hdr) + + offsetof(struct _fpstate_32, _fxsr_env)); + to_fp64 = (void *)to_fp + offsetof(struct _fpstate_32, _fxsr_env); #else - if (copy_to_user(to_fp, regs->regs.fp, sizeof(struct _xstate))) + to_fp64 = to_fp; +#endif /* CONFIG_X86_32 */ + + if (copy_to_user(to_fp64, regs->regs.fp, host_fp_size)) return 1; + + /* + * Put magic/size values for userspace. We do not bother to verify them + * later on, however, userspace needs them should it try to read the + * XSTATE data. And ptrace does not fill in these parts. + */ + BUILD_BUG_ON(sizeof(int) != FP_XSTATE_MAGIC2_SIZE); +#ifdef CONFIG_X86_32 + __put_user(offsetof(struct _fpstate_32, _fxsr_env) + + host_fp_size + FP_XSTATE_MAGIC2_SIZE, + &to_fp64->fpstate.sw_reserved.extended_size); +#else + __put_user(host_fp_size + FP_XSTATE_MAGIC2_SIZE, + &to_fp64->fpstate.sw_reserved.extended_size); #endif + __put_user(host_fp_size, &to_fp64->fpstate.sw_reserved.xstate_size); + + __put_user(FP_XSTATE_MAGIC1, &to_fp64->fpstate.sw_reserved.magic1); + __put_user(FP_XSTATE_MAGIC2, (int *)((void *)to_fp64 + host_fp_size)); return 0; } @@ -333,34 +216,15 @@ static int copy_ucontext_to_user(struct ucontext __user *uc, return err; } -struct sigframe -{ - char __user *pretcode; - int sig; - struct sigcontext sc; - struct _xstate fpstate; - unsigned long extramask[_NSIG_WORDS-1]; - char retcode[8]; -}; - -struct rt_sigframe -{ - char __user *pretcode; - int sig; - struct siginfo __user *pinfo; - void __user *puc; - struct siginfo info; - struct ucontext uc; - struct _xstate fpstate; - char retcode[8]; -}; - int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig, struct pt_regs *regs, sigset_t *mask) { + size_t math_size = offsetof(struct _fpstate_32, _fxsr_env) + + host_fp_size + FP_XSTATE_MAGIC2_SIZE; struct sigframe __user *frame; void __user *restorer; int err = 0, sig = ksig->sig; + unsigned long fp_to; /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */ stack_top = ((stack_top + 4) & -16UL) - 4; @@ -368,13 +232,21 @@ int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig, if (!access_ok(frame, sizeof(*frame))) return 1; + /* Add required space for math frame */ + frame = (struct sigframe __user *)((unsigned long)frame - math_size); + restorer = frame->retcode; if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; - err |= __put_user(restorer, &frame->pretcode); + err |= __put_user(restorer, (void **)&frame->pretcode); err |= __put_user(sig, &frame->sig); - err |= copy_sc_to_user(&frame->sc, &frame->fpstate, regs, mask->sig[0]); + + fp_to = (unsigned long)frame + sizeof(*frame); + + err |= copy_sc_to_user(&frame->sc, + (struct _xstate __user *)fp_to, + regs, mask->sig[0]); if (_NSIG_WORDS > 1) err |= __copy_to_user(&frame->extramask, &mask->sig[1], sizeof(frame->extramask)); @@ -404,26 +276,35 @@ int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig, int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig, struct pt_regs *regs, sigset_t *mask) { + size_t math_size = offsetof(struct _fpstate_32, _fxsr_env) + + host_fp_size + FP_XSTATE_MAGIC2_SIZE; struct rt_sigframe __user *frame; void __user *restorer; int err = 0, sig = ksig->sig; + unsigned long fp_to; stack_top &= -8UL; frame = (struct rt_sigframe __user *) stack_top - 1; if (!access_ok(frame, sizeof(*frame))) return 1; + /* Add required space for math frame */ + frame = (struct rt_sigframe __user *)((unsigned long)frame - math_size); + restorer = frame->retcode; if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; - err |= __put_user(restorer, &frame->pretcode); + err |= __put_user(restorer, (void **)&frame->pretcode); err |= __put_user(sig, &frame->sig); - err |= __put_user(&frame->info, &frame->pinfo); - err |= __put_user(&frame->uc, &frame->puc); + err |= __put_user(&frame->info, (void **)&frame->pinfo); + err |= __put_user(&frame->uc, (void **)&frame->puc); err |= copy_siginfo_to_user(&frame->info, &ksig->info); - err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask, - PT_REGS_SP(regs)); + + fp_to = (unsigned long)frame + sizeof(*frame); + + err |= copy_ucontext_to_user(&frame->uc, (struct _xstate __user *)fp_to, + mask, PT_REGS_SP(regs)); /* * This is movl $,%eax ; int $0x80 @@ -475,27 +356,24 @@ SYSCALL_DEFINE0(sigreturn) #else -struct rt_sigframe -{ - char __user *pretcode; - struct ucontext uc; - struct siginfo info; - struct _xstate fpstate; -}; - int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig, struct pt_regs *regs, sigset_t *set) { + unsigned long math_size = host_fp_size + FP_XSTATE_MAGIC2_SIZE; struct rt_sigframe __user *frame; int err = 0, sig = ksig->sig; unsigned long fp_to; frame = (struct rt_sigframe __user *) round_down(stack_top - sizeof(struct rt_sigframe), 16); + + /* Add required space for math frame */ + frame = (struct rt_sigframe __user *)((unsigned long)frame - math_size); + /* Subtract 128 for a red zone and 8 for proper alignment */ frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8); - if (!access_ok(frame, sizeof(*frame))) + if (!access_ok(frame, sizeof(*frame) + math_size)) goto out; if (ksig->ka.sa.sa_flags & SA_SIGINFO) { @@ -508,10 +386,12 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig, err |= __put_user(0, &frame->uc.uc_flags); err |= __put_user(0, &frame->uc.uc_link); err |= __save_altstack(&frame->uc.uc_stack, PT_REGS_SP(regs)); - err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs, - set->sig[0]); - fp_to = (unsigned long)&frame->fpstate; + fp_to = (unsigned long)frame + sizeof(*frame); + + err |= copy_sc_to_user(&frame->uc.uc_mcontext, + (struct _xstate __user *)fp_to, + regs, set->sig[0]); err |= __put_user(fp_to, &frame->uc.uc_mcontext.fpstate); if (sizeof(*set) == 16) { |