Commit 1bd79336 authored by Paul Mackerras's avatar Paul Mackerras

powerpc: Fix various syscall/signal/swapcontext bugs

A careful reading of the recent changes to the system call entry/exit
paths revealed several problems, plus some things that could be
simplified and improved:

* 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit
  path, so it was only doing anything with it once it saw some other
  bit being set.  In other words, the noerror behaviour would apply to
  the next system call where we had to reschedule or deliver a signal,
  which is not necessarily the current system call.

* 32-bit wasn't doing the call to ptrace_notify in the syscall exit
  path when the _TIF_SINGLESTEP bit was set.

* _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and
  _TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set
  by system calls.  I took it out of _TIF_USER_WORK_MASK.

* On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers
  to be restored (unless perhaps a signal was delivered or the syscall
  was traced or single-stepped).  Thus the non-volatile registers
  weren't restored on exit from a signal handler.  We probably got
  away with it mostly because signal handlers written in C wouldn't
  alter the non-volatile registers.

* On 32-bit I simplified the code and made it more like 64-bit by
  making the syscall exit path jump to ret_from_except to handle
  preemption and signal delivery.

* 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was
  set - but I think because of that 32-bit was actually restoring the
  non-volatile registers on exit from a signal handler.

* I changed the order of enabling interrupts and saving the
  non-volatile registers before calling do_syscall_trace_leave; now we
  enable interrupts first.
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent ab1b55e2
......@@ -92,7 +92,6 @@ int main(void)
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
DEFINE(TI_SIGFRAME, offsetof(struct thread_info, nvgprs_frame));
DEFINE(TI_TASK, offsetof(struct thread_info, task));
#ifdef CONFIG_PPC32
DEFINE(TI_EXECDOMAIN, offsetof(struct thread_info, exec_domain));
......
......@@ -227,7 +227,7 @@ ret_from_syscall:
MTMSRD(r10)
lwz r9,TI_FLAGS(r12)
li r8,-_LAST_ERRNO
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL|_TIF_RESTORE_SIGMASK)
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work
cmplw 0,r3,r8
blt+ syscall_exit_cont
......@@ -287,8 +287,10 @@ syscall_dotrace:
syscall_exit_work:
andi. r0,r9,_TIF_RESTOREALL
bne- 2f
cmplw 0,r3,r8
beq+ 0f
REST_NVGPRS(r1)
b 2f
0: cmplw 0,r3,r8
blt+ 1f
andi. r0,r9,_TIF_NOERROR
bne- 1f
......@@ -302,9 +304,7 @@ syscall_exit_work:
2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
beq 4f
/* Clear per-syscall TIF flags if any are set, but _leave_
_TIF_SAVE_NVGPRS set in r9 since we haven't dealt with that
yet. */
/* Clear per-syscall TIF flags if any are set. */
li r11,_TIF_PERSYSCALL_MASK
addi r12,r12,TI_FLAGS
......@@ -318,8 +318,13 @@ syscall_exit_work:
subi r12,r12,TI_FLAGS
4: /* Anything which requires enabling interrupts? */
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_SAVE_NVGPRS)
beq 7f
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq ret_from_except
/* Re-enable interrupts */
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10)
/* Save NVGPRS if they're not saved already */
lwz r4,_TRAP(r1)
......@@ -328,71 +333,11 @@ syscall_exit_work:
SAVE_NVGPRS(r1)
li r4,0xc00
stw r4,_TRAP(r1)
/* Re-enable interrupts */
5: ori r10,r10,MSR_EE
SYNC
MTMSRD(r10)
andi. r0,r9,_TIF_SAVE_NVGPRS
bne save_user_nvgprs
save_user_nvgprs_cont:
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq 7f
5:
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_leave
REST_NVGPRS(r1)
6: lwz r3,GPR3(r1)
LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
SYNC
MTMSRD(r10) /* disable interrupts again */
rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
lwz r9,TI_FLAGS(r12)
7:
andi. r0,r9,_TIF_NEED_RESCHED
bne 8f
lwz r5,_MSR(r1)
andi. r5,r5,MSR_PR
beq ret_from_except
andi. r0,r9,_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK
beq ret_from_except
b do_user_signal
8:
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10) /* re-enable interrupts */
bl schedule
b 6b
save_user_nvgprs:
lwz r8,TI_SIGFRAME(r12)
.macro savewords start, end
1: stw \start,4*(\start)(r8)
.section __ex_table,"a"
.align 2
.long 1b,save_user_nvgprs_fault
.previous
.if \end - \start
savewords "(\start+1)",\end
.endif
.endm
savewords 14,31
b save_user_nvgprs_cont
save_user_nvgprs_fault:
li r3,11 /* SIGSEGV */
lwz r4,TI_TASK(r12)
bl force_sigsegv
b ret_from_except_full
rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
lwz r9,TI_FLAGS(r12)
b save_user_nvgprs_cont
#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
......@@ -490,6 +435,14 @@ ppc_clone:
stw r0,_TRAP(r1) /* register set saved */
b sys_clone
.globl ppc_swapcontext
ppc_swapcontext:
SAVE_NVGPRS(r1)
lwz r0,_TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,_TRAP(r1) /* register set saved */
b sys_swapcontext
/*
* Top-level page fault handling.
* This is in assembler because if do_page_fault tells us that
......@@ -683,7 +636,7 @@ user_exc_return: /* r10 contains MSR_KERNEL here */
/* Check current_thread_info()->flags */
rlwinm r9,r1,0,0,(31-THREAD_SHIFT)
lwz r9,TI_FLAGS(r9)
andi. r0,r9,(_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL|_TIF_RESTORE_SIGMASK)
andi. r0,r9,(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NEED_RESCHED)
bne do_work
restore_user:
......
......@@ -160,7 +160,7 @@ syscall_exit:
mtmsrd r10,1
ld r9,TI_FLAGS(r12)
li r11,-_LAST_ERRNO
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL|_TIF_SAVE_NVGPRS|_TIF_NOERROR|_TIF_RESTORE_SIGMASK)
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work
cmpld r3,r11
ld r5,_CCR(r1)
......@@ -216,8 +216,10 @@ syscall_exit_work:
If TIF_NOERROR is set, just save r3 as it is. */
andi. r0,r9,_TIF_RESTOREALL
bne- 2f
cmpld r3,r11 /* r10 is -LAST_ERRNO */
beq+ 0f
REST_NVGPRS(r1)
b 2f
0: cmpld r3,r11 /* r10 is -LAST_ERRNO */
blt+ 1f
andi. r0,r9,_TIF_NOERROR
bne- 1f
......@@ -229,9 +231,7 @@ syscall_exit_work:
2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
beq 4f
/* Clear per-syscall TIF flags if any are set, but _leave_
_TIF_SAVE_NVGPRS set in r9 since we haven't dealt with that
yet. */
/* Clear per-syscall TIF flags if any are set. */
li r11,_TIF_PERSYSCALL_MASK
addi r12,r12,TI_FLAGS
......@@ -240,10 +240,9 @@ syscall_exit_work:
stdcx. r10,0,r12
bne- 3b
subi r12,r12,TI_FLAGS
4: bl .save_nvgprs
/* Anything else left to do? */
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_SAVE_NVGPRS)
4: /* Anything else left to do? */
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq .ret_from_except_lite
/* Re-enable interrupts */
......@@ -251,26 +250,10 @@ syscall_exit_work:
ori r10,r10,MSR_EE
mtmsrd r10,1
andi. r0,r9,_TIF_SAVE_NVGPRS
bne save_user_nvgprs
/* If tracing, re-enable interrupts and do it */
save_user_nvgprs_cont:
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq 5f
bl .save_nvgprs
addi r3,r1,STACK_FRAME_OVERHEAD
bl .do_syscall_trace_leave
REST_NVGPRS(r1)
clrrdi r12,r1,THREAD_SHIFT
/* Disable interrupts again and handle other work if any */
5: mfmsr r10
rldicl r10,r10,48,1
rotldi r10,r10,16
mtmsrd r10,1
b .ret_from_except_lite
b .ret_from_except
/* Save non-volatile GPRs, if not already saved. */
_GLOBAL(save_nvgprs)
......@@ -282,51 +265,6 @@ _GLOBAL(save_nvgprs)
std r0,_TRAP(r1)
blr
save_user_nvgprs:
ld r10,TI_SIGFRAME(r12)
andi. r0,r9,_TIF_32BIT
beq- save_user_nvgprs_64
/* 32-bit save to userspace */
.macro savewords start, end
1: stw \start,4*(\start)(r10)
.section __ex_table,"a"
.align 3
.llong 1b,save_user_nvgprs_fault
.previous
.if \end - \start
savewords "(\start+1)",\end
.endif
.endm
savewords 14,31
b save_user_nvgprs_cont
save_user_nvgprs_64:
/* 64-bit save to userspace */
.macro savelongs start, end
1: std \start,8*(\start)(r10)
.section __ex_table,"a"
.align 3
.llong 1b,save_user_nvgprs_fault
.previous
.if \end - \start
savelongs "(\start+1)",\end
.endif
.endm
savelongs 14,31
b save_user_nvgprs_cont
save_user_nvgprs_fault:
li r3,11 /* SIGSEGV */
ld r4,TI_TASK(r12)
bl .force_sigsegv
clrrdi r12,r1,THREAD_SHIFT
ld r9,TI_FLAGS(r12)
b save_user_nvgprs_cont
/*
* The sigsuspend and rt_sigsuspend system calls can call do_signal
......@@ -352,6 +290,16 @@ _GLOBAL(ppc_clone)
bl .sys_clone
b syscall_exit
_GLOBAL(ppc32_swapcontext)
bl .save_nvgprs
bl .compat_sys_swapcontext
b syscall_exit
_GLOBAL(ppc64_swapcontext)
bl .save_nvgprs
bl .sys_swapcontext
b syscall_exit
_GLOBAL(ret_from_fork)
bl .schedule_tail
REST_NVGPRS(r1)
......
......@@ -561,10 +561,7 @@ void do_syscall_trace_leave(struct pt_regs *regs)
regs->result);
if ((test_thread_flag(TIF_SYSCALL_TRACE)
#ifdef CONFIG_PPC64
|| test_thread_flag(TIF_SINGLESTEP)
#endif
)
|| test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
do_syscall_trace();
}
......
......@@ -151,10 +151,7 @@ static inline int save_general_regs(struct pt_regs *regs,
elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
int i;
if (!FULL_REGS(regs)) {
set_thread_flag(TIF_SAVE_NVGPRS);
current_thread_info()->nvgprs_frame = frame->mc_gregs;
}
WARN_ON(!FULL_REGS(regs));
for (i = 0; i <= PT_RESULT; i ++) {
if (i == 14 && !FULL_REGS(regs))
......@@ -215,15 +212,7 @@ static inline int get_old_sigaction(struct k_sigaction *new_ka,
static inline int save_general_regs(struct pt_regs *regs,
struct mcontext __user *frame)
{
if (!FULL_REGS(regs)) {
/* Zero out the unsaved GPRs to avoid information
leak, and set TIF_SAVE_NVGPRS to ensure that the
registers do actually get saved later. */
memset(&regs->gpr[14], 0, 18 * sizeof(unsigned long));
current_thread_info()->nvgprs_frame = &frame->mc_gregs;
set_thread_flag(TIF_SAVE_NVGPRS);
}
WARN_ON(!FULL_REGS(regs));
return __copy_to_user(&frame->mc_gregs, regs, GP_REGS_SIZE);
}
......@@ -826,8 +815,8 @@ static int do_setcontext(struct ucontext __user *ucp, struct pt_regs *regs, int
}
long sys_swapcontext(struct ucontext __user *old_ctx,
struct ucontext __user *new_ctx,
int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
struct ucontext __user *new_ctx,
int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
{
unsigned char tmp;
......
......@@ -118,14 +118,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */
err |= __put_user(&sc->gp_regs, &sc->regs);
if (!FULL_REGS(regs)) {
/* Zero out the unsaved GPRs to avoid information
leak, and set TIF_SAVE_NVGPRS to ensure that the
registers do actually get saved later. */
memset(&regs->gpr[14], 0, 18 * sizeof(unsigned long));
set_thread_flag(TIF_SAVE_NVGPRS);
current_thread_info()->nvgprs_frame = &sc->gp_regs;
}
WARN_ON(!FULL_REGS(regs));
err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
err |= __put_user(signr, &sc->signal);
......
......@@ -288,7 +288,7 @@ COMPAT_SYS(clock_settime)
COMPAT_SYS(clock_gettime)
COMPAT_SYS(clock_getres)
COMPAT_SYS(clock_nanosleep)
COMPAT_SYS(swapcontext)
SYSX(ppc64_swapcontext,ppc32_swapcontext,ppc_swapcontext)
COMPAT_SYS(tgkill)
COMPAT_SYS(utimes)
COMPAT_SYS(statfs64)
......
......@@ -131,7 +131,6 @@ main(void)
DEFINE(CPU_SPEC_FEATURES, offsetof(struct cpu_spec, cpu_features));
DEFINE(CPU_SPEC_SETUP, offsetof(struct cpu_spec, cpu_setup));
DEFINE(TI_SIGFRAME, offsetof(struct thread_info, nvgprs_frame));
DEFINE(TI_TASK, offsetof(struct thread_info, task));
DEFINE(TI_EXECDOMAIN, offsetof(struct thread_info, exec_domain));
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
......
......@@ -227,7 +227,7 @@ ret_from_syscall:
MTMSRD(r10)
lwz r9,TI_FLAGS(r12)
li r8,-_LAST_ERRNO
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL)
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work
cmplw 0,r3,r8
blt+ syscall_exit_cont
......@@ -287,8 +287,10 @@ syscall_dotrace:
syscall_exit_work:
andi. r0,r9,_TIF_RESTOREALL
bne- 2f
cmplw 0,r3,r8
beq+ 0f
REST_NVGPRS(r1)
b 2f
0: cmplw 0,r3,r8
blt+ 1f
andi. r0,r9,_TIF_NOERROR
bne- 1f
......@@ -302,9 +304,7 @@ syscall_exit_work:
2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
beq 4f
/* Clear per-syscall TIF flags if any are set, but _leave_
_TIF_SAVE_NVGPRS set in r9 since we haven't dealt with that
yet. */
/* Clear per-syscall TIF flags if any are set. */
li r11,_TIF_PERSYSCALL_MASK
addi r12,r12,TI_FLAGS
......@@ -318,8 +318,13 @@ syscall_exit_work:
subi r12,r12,TI_FLAGS
4: /* Anything which requires enabling interrupts? */
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_SAVE_NVGPRS)
beq 7f
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq ret_from_except
/* Re-enable interrupts */
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10)
/* Save NVGPRS if they're not saved already */
lwz r4,TRAP(r1)
......@@ -328,71 +333,11 @@ syscall_exit_work:
SAVE_NVGPRS(r1)
li r4,0xc00
stw r4,TRAP(r1)
/* Re-enable interrupts */
5: ori r10,r10,MSR_EE
SYNC
MTMSRD(r10)
andi. r0,r9,_TIF_SAVE_NVGPRS
bne save_user_nvgprs
save_user_nvgprs_cont:
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq 7f
5:
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_leave
REST_NVGPRS(r1)
6: lwz r3,GPR3(r1)
LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
SYNC
MTMSRD(r10) /* disable interrupts again */
rlwinm r12,r1,0,0,18 /* current_thread_info() */
lwz r9,TI_FLAGS(r12)
7:
andi. r0,r9,_TIF_NEED_RESCHED
bne 8f
lwz r5,_MSR(r1)
andi. r5,r5,MSR_PR
beq ret_from_except
andi. r0,r9,_TIF_SIGPENDING
beq ret_from_except
b do_user_signal
8:
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10) /* re-enable interrupts */
bl schedule
b 6b
save_user_nvgprs:
lwz r8,TI_SIGFRAME(r12)
.macro savewords start, end
1: stw \start,4*(\start)(r8)
.section __ex_table,"a"
.align 2
.long 1b,save_user_nvgprs_fault
.previous
.if \end - \start
savewords "(\start+1)",\end
.endif
.endm
savewords 14,31
b save_user_nvgprs_cont
save_user_nvgprs_fault:
li r3,11 /* SIGSEGV */
lwz r4,TI_TASK(r12)
bl force_sigsegv
b ret_from_except_full
rlwinm r12,r1,0,0,18 /* current_thread_info() */
lwz r9,TI_FLAGS(r12)
b save_user_nvgprs_cont
#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
......@@ -490,6 +435,14 @@ ppc_clone:
stw r0,TRAP(r1) /* register set saved */
b sys_clone
.globl ppc_swapcontext
ppc_swapcontext:
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,TRAP(r1) /* register set saved */
b sys_swapcontext
/*
* Top-level page fault handling.
* This is in assembler because if do_page_fault tells us that
......@@ -683,7 +636,7 @@ user_exc_return: /* r10 contains MSR_KERNEL here */
/* Check current_thread_info()->flags */
rlwinm r9,r1,0,0,18
lwz r9,TI_FLAGS(r9)
andi. r0,r9,(_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL)
andi. r0,r9,(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NEED_RESCHED)
bne do_work
restore_user:
......
......@@ -37,7 +37,6 @@ struct thread_info {
int preempt_count; /* 0 => preemptable,
<0 => BUG */
struct restart_block restart_block;
void __user *nvgprs_frame;
/* low level flags - has atomic operations done on it */
unsigned long flags ____cacheline_aligned_in_smp;
};
......@@ -120,7 +119,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_MEMDIE 10
#define TIF_SECCOMP 11 /* secure computing */
#define TIF_RESTOREALL 12 /* Restore all regs (implies NOERROR) */
#define TIF_SAVE_NVGPRS 13 /* Save r14-r31 in signal frame */
#define TIF_NOERROR 14 /* Force successful syscall return */
#define TIF_RESTORE_SIGMASK 15 /* Restore signal mask in do_signal */
......@@ -137,15 +135,13 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
#define _TIF_SAVE_NVGPRS (1<<TIF_SAVE_NVGPRS)
#define _TIF_NOERROR (1<<TIF_NOERROR)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_SYSCALL_T_OR_A (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)
#define _TIF_USER_WORK_MASK (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
_TIF_NEED_RESCHED | _TIF_RESTOREALL | \
_TIF_RESTORE_SIGMASK)
#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR|_TIF_SAVE_NVGPRS)
_TIF_NEED_RESCHED | _TIF_RESTORE_SIGMASK)
#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
#endif /* __KERNEL__ */
......
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