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sparc: Allow handling signals when stack is corrupted.
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If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.

Add a register window save area in the signal frame, and store any
unsavable windows there.

On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.

This allows the debug/tst-longjmp_chk2 glibc test case to pass.

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Aug 21, 2011
1 parent 4a0342c commit 5598473
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Showing 8 changed files with 468 additions and 233 deletions.
14 changes: 14 additions & 0 deletions arch/sparc/include/asm/sigcontext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,19 @@ typedef struct {
int si_mask;
} __siginfo32_t;

#define __SIGC_MAXWIN 7

typedef struct {
unsigned long locals[8];
unsigned long ins[8];
} __siginfo_reg_window;

typedef struct {
int wsaved;
__siginfo_reg_window reg_window[__SIGC_MAXWIN];
unsigned long rwbuf_stkptrs[__SIGC_MAXWIN];
} __siginfo_rwin_t;

#ifdef CONFIG_SPARC64
typedef struct {
unsigned int si_float_regs [64];
Expand Down Expand Up @@ -73,6 +86,7 @@ struct sigcontext {
unsigned long ss_size;
} sigc_stack;
unsigned long sigc_mask;
__siginfo_rwin_t * sigc_rwin_save;
};

#else
Expand Down
1 change: 1 addition & 0 deletions arch/sparc/kernel/Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ obj-$(CONFIG_SPARC32) += sun4m_irq.o sun4c_irq.o sun4d_irq.o

obj-y += process_$(BITS).o
obj-y += signal_$(BITS).o
obj-y += sigutil_$(BITS).o
obj-$(CONFIG_SPARC32) += ioport.o
obj-y += setup_$(BITS).o
obj-y += idprom.o
Expand Down
184 changes: 105 additions & 79 deletions arch/sparc/kernel/signal32.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@
#include <asm/visasm.h>
#include <asm/compat_signal.h>

#include "sigutil.h"

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/* This magic should be in g_upper[0] for all upper parts
Expand All @@ -44,14 +46,14 @@ typedef struct {
struct signal_frame32 {
struct sparc_stackf32 ss;
__siginfo32_t info;
/* __siginfo_fpu32_t * */ u32 fpu_save;
/* __siginfo_fpu_t * */ u32 fpu_save;
unsigned int insns[2];
unsigned int extramask[_COMPAT_NSIG_WORDS - 1];
unsigned int extra_size; /* Should be sizeof(siginfo_extra_v8plus_t) */
/* Only valid if (info.si_regs.psr & (PSR_VERS|PSR_IMPL)) == PSR_V8PLUS */
siginfo_extra_v8plus_t v8plus;
__siginfo_fpu_t fpu_state;
};
/* __siginfo_rwin_t * */u32 rwin_save;
} __attribute__((aligned(8)));

typedef struct compat_siginfo{
int si_signo;
Expand Down Expand Up @@ -110,18 +112,14 @@ struct rt_signal_frame32 {
compat_siginfo_t info;
struct pt_regs32 regs;
compat_sigset_t mask;
/* __siginfo_fpu32_t * */ u32 fpu_save;
/* __siginfo_fpu_t * */ u32 fpu_save;
unsigned int insns[2];
stack_t32 stack;
unsigned int extra_size; /* Should be sizeof(siginfo_extra_v8plus_t) */
/* Only valid if (regs.psr & (PSR_VERS|PSR_IMPL)) == PSR_V8PLUS */
siginfo_extra_v8plus_t v8plus;
__siginfo_fpu_t fpu_state;
};

/* Align macros */
#define SF_ALIGNEDSZ (((sizeof(struct signal_frame32) + 15) & (~15)))
#define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame32) + 15) & (~15)))
/* __siginfo_rwin_t * */u32 rwin_save;
} __attribute__((aligned(8)));

int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
Expand Down Expand Up @@ -192,30 +190,13 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
return 0;
}

static int restore_fpu_state32(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
{
unsigned long *fpregs = current_thread_info()->fpregs;
unsigned long fprs;
int err;

err = __get_user(fprs, &fpu->si_fprs);
fprs_write(0);
regs->tstate &= ~TSTATE_PEF;
if (fprs & FPRS_DL)
err |= copy_from_user(fpregs, &fpu->si_float_regs[0], (sizeof(unsigned int) * 32));
if (fprs & FPRS_DU)
err |= copy_from_user(fpregs+16, &fpu->si_float_regs[32], (sizeof(unsigned int) * 32));
err |= __get_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
err |= __get_user(current_thread_info()->gsr[0], &fpu->si_gsr);
current_thread_info()->fpsaved[0] |= fprs;
return err;
}

void do_sigreturn32(struct pt_regs *regs)
{
struct signal_frame32 __user *sf;
compat_uptr_t fpu_save;
compat_uptr_t rwin_save;
unsigned int psr;
unsigned pc, npc, fpu_save;
unsigned pc, npc;
sigset_t set;
unsigned seta[_COMPAT_NSIG_WORDS];
int err, i;
Expand Down Expand Up @@ -273,8 +254,13 @@ void do_sigreturn32(struct pt_regs *regs)
pt_regs_clear_syscall(regs);

err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
err |= restore_fpu_state32(regs, &sf->fpu_state);
if (!err && fpu_save)
err |= restore_fpu_state(regs, compat_ptr(fpu_save));
err |= __get_user(rwin_save, &sf->rwin_save);
if (!err && rwin_save) {
if (restore_rwin_state(compat_ptr(rwin_save)))
goto segv;
}
err |= __get_user(seta[0], &sf->info.si_mask);
err |= copy_from_user(seta+1, &sf->extramask,
(_COMPAT_NSIG_WORDS - 1) * sizeof(unsigned int));
Expand All @@ -300,7 +286,9 @@ void do_sigreturn32(struct pt_regs *regs)
asmlinkage void do_rt_sigreturn32(struct pt_regs *regs)
{
struct rt_signal_frame32 __user *sf;
unsigned int psr, pc, npc, fpu_save, u_ss_sp;
unsigned int psr, pc, npc, u_ss_sp;
compat_uptr_t fpu_save;
compat_uptr_t rwin_save;
mm_segment_t old_fs;
sigset_t set;
compat_sigset_t seta;
Expand Down Expand Up @@ -359,8 +347,8 @@ asmlinkage void do_rt_sigreturn32(struct pt_regs *regs)
pt_regs_clear_syscall(regs);

err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
err |= restore_fpu_state32(regs, &sf->fpu_state);
if (!err && fpu_save)
err |= restore_fpu_state(regs, compat_ptr(fpu_save));
err |= copy_from_user(&seta, &sf->mask, sizeof(compat_sigset_t));
err |= __get_user(u_ss_sp, &sf->stack.ss_sp);
st.ss_sp = compat_ptr(u_ss_sp);
Expand All @@ -376,6 +364,12 @@ asmlinkage void do_rt_sigreturn32(struct pt_regs *regs)
do_sigaltstack((stack_t __user *) &st, NULL, (unsigned long)sf);
set_fs(old_fs);

err |= __get_user(rwin_save, &sf->rwin_save);
if (!err && rwin_save) {
if (restore_rwin_state(compat_ptr(rwin_save)))
goto segv;
}

switch (_NSIG_WORDS) {
case 4: set.sig[3] = seta.sig[6] + (((long)seta.sig[7]) << 32);
case 3: set.sig[2] = seta.sig[4] + (((long)seta.sig[5]) << 32);
Expand Down Expand Up @@ -433,26 +427,6 @@ static void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, uns
return (void __user *) sp;
}

static int save_fpu_state32(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
{
unsigned long *fpregs = current_thread_info()->fpregs;
unsigned long fprs;
int err = 0;

fprs = current_thread_info()->fpsaved[0];
if (fprs & FPRS_DL)
err |= copy_to_user(&fpu->si_float_regs[0], fpregs,
(sizeof(unsigned int) * 32));
if (fprs & FPRS_DU)
err |= copy_to_user(&fpu->si_float_regs[32], fpregs+16,
(sizeof(unsigned int) * 32));
err |= __put_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
err |= __put_user(current_thread_info()->gsr[0], &fpu->si_gsr);
err |= __put_user(fprs, &fpu->si_fprs);

return err;
}

/* The I-cache flush instruction only works in the primary ASI, which
* right now is the nucleus, aka. kernel space.
*
Expand Down Expand Up @@ -515,27 +489,31 @@ static int setup_frame32(struct k_sigaction *ka, struct pt_regs *regs,
int signo, sigset_t *oldset)
{
struct signal_frame32 __user *sf;
int i, err, wsaved;
void __user *tail;
int sigframe_size;
u32 psr;
int i, err;
unsigned int seta[_COMPAT_NSIG_WORDS];

/* 1. Make sure everything is clean */
synchronize_user_stack();
save_and_clear_fpu();

sigframe_size = SF_ALIGNEDSZ;
if (!(current_thread_info()->fpsaved[0] & FPRS_FEF))
sigframe_size -= sizeof(__siginfo_fpu_t);
wsaved = get_thread_wsaved();

sigframe_size = sizeof(*sf);
if (current_thread_info()->fpsaved[0] & FPRS_FEF)
sigframe_size += sizeof(__siginfo_fpu_t);
if (wsaved)
sigframe_size += sizeof(__siginfo_rwin_t);

sf = (struct signal_frame32 __user *)
get_sigframe(&ka->sa, regs, sigframe_size);

if (invalid_frame_pointer(sf, sigframe_size))
goto sigill;

if (get_thread_wsaved() != 0)
goto sigill;
tail = (sf + 1);

/* 2. Save the current process state */
if (test_thread_flag(TIF_32BIT)) {
Expand All @@ -560,11 +538,22 @@ static int setup_frame32(struct k_sigaction *ka, struct pt_regs *regs,
&sf->v8plus.asi);

if (psr & PSR_EF) {
err |= save_fpu_state32(regs, &sf->fpu_state);
err |= __put_user((u64)&sf->fpu_state, &sf->fpu_save);
__siginfo_fpu_t __user *fp = tail;
tail += sizeof(*fp);
err |= save_fpu_state(regs, fp);
err |= __put_user((u64)fp, &sf->fpu_save);
} else {
err |= __put_user(0, &sf->fpu_save);
}
if (wsaved) {
__siginfo_rwin_t __user *rwp = tail;
tail += sizeof(*rwp);
err |= save_rwin_state(wsaved, rwp);
err |= __put_user((u64)rwp, &sf->rwin_save);
set_thread_wsaved(0);
} else {
err |= __put_user(0, &sf->rwin_save);
}

switch (_NSIG_WORDS) {
case 4: seta[7] = (oldset->sig[3] >> 32);
Expand All @@ -580,10 +569,21 @@ static int setup_frame32(struct k_sigaction *ka, struct pt_regs *regs,
err |= __copy_to_user(sf->extramask, seta + 1,
(_COMPAT_NSIG_WORDS - 1) * sizeof(unsigned int));

err |= copy_in_user((u32 __user *)sf,
(u32 __user *)(regs->u_regs[UREG_FP]),
sizeof(struct reg_window32));

if (!wsaved) {
err |= copy_in_user((u32 __user *)sf,
(u32 __user *)(regs->u_regs[UREG_FP]),
sizeof(struct reg_window32));
} else {
struct reg_window *rp;

rp = &current_thread_info()->reg_window[wsaved - 1];
for (i = 0; i < 8; i++)
err |= __put_user(rp->locals[i], &sf->ss.locals[i]);
for (i = 0; i < 6; i++)
err |= __put_user(rp->ins[i], &sf->ss.ins[i]);
err |= __put_user(rp->ins[6], &sf->ss.fp);
err |= __put_user(rp->ins[7], &sf->ss.callers_pc);
}
if (err)
goto sigsegv;

Expand Down Expand Up @@ -613,7 +613,6 @@ static int setup_frame32(struct k_sigaction *ka, struct pt_regs *regs,
err |= __put_user(0x91d02010, &sf->insns[1]); /*t 0x10*/
if (err)
goto sigsegv;

flush_signal_insns(address);
}
return 0;
Expand All @@ -632,27 +631,31 @@ static int setup_rt_frame32(struct k_sigaction *ka, struct pt_regs *regs,
siginfo_t *info)
{
struct rt_signal_frame32 __user *sf;
int i, err, wsaved;
void __user *tail;
int sigframe_size;
u32 psr;
int i, err;
compat_sigset_t seta;

/* 1. Make sure everything is clean */
synchronize_user_stack();
save_and_clear_fpu();

sigframe_size = RT_ALIGNEDSZ;
if (!(current_thread_info()->fpsaved[0] & FPRS_FEF))
sigframe_size -= sizeof(__siginfo_fpu_t);
wsaved = get_thread_wsaved();

sigframe_size = sizeof(*sf);
if (current_thread_info()->fpsaved[0] & FPRS_FEF)
sigframe_size += sizeof(__siginfo_fpu_t);
if (wsaved)
sigframe_size += sizeof(__siginfo_rwin_t);

sf = (struct rt_signal_frame32 __user *)
get_sigframe(&ka->sa, regs, sigframe_size);

if (invalid_frame_pointer(sf, sigframe_size))
goto sigill;

if (get_thread_wsaved() != 0)
goto sigill;
tail = (sf + 1);

/* 2. Save the current process state */
if (test_thread_flag(TIF_32BIT)) {
Expand All @@ -677,11 +680,22 @@ static int setup_rt_frame32(struct k_sigaction *ka, struct pt_regs *regs,
&sf->v8plus.asi);

if (psr & PSR_EF) {
err |= save_fpu_state32(regs, &sf->fpu_state);
err |= __put_user((u64)&sf->fpu_state, &sf->fpu_save);
__siginfo_fpu_t __user *fp = tail;
tail += sizeof(*fp);
err |= save_fpu_state(regs, fp);
err |= __put_user((u64)fp, &sf->fpu_save);
} else {
err |= __put_user(0, &sf->fpu_save);
}
if (wsaved) {
__siginfo_rwin_t __user *rwp = tail;
tail += sizeof(*rwp);
err |= save_rwin_state(wsaved, rwp);
err |= __put_user((u64)rwp, &sf->rwin_save);
set_thread_wsaved(0);
} else {
err |= __put_user(0, &sf->rwin_save);
}

/* Update the siginfo structure. */
err |= copy_siginfo_to_user32(&sf->info, info);
Expand All @@ -703,9 +717,21 @@ static int setup_rt_frame32(struct k_sigaction *ka, struct pt_regs *regs,
}
err |= __copy_to_user(&sf->mask, &seta, sizeof(compat_sigset_t));

err |= copy_in_user((u32 __user *)sf,
(u32 __user *)(regs->u_regs[UREG_FP]),
sizeof(struct reg_window32));
if (!wsaved) {
err |= copy_in_user((u32 __user *)sf,
(u32 __user *)(regs->u_regs[UREG_FP]),
sizeof(struct reg_window32));
} else {
struct reg_window *rp;

rp = &current_thread_info()->reg_window[wsaved - 1];
for (i = 0; i < 8; i++)
err |= __put_user(rp->locals[i], &sf->ss.locals[i]);
for (i = 0; i < 6; i++)
err |= __put_user(rp->ins[i], &sf->ss.ins[i]);
err |= __put_user(rp->ins[6], &sf->ss.fp);
err |= __put_user(rp->ins[7], &sf->ss.callers_pc);
}
if (err)
goto sigsegv;

Expand Down
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