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authorPaul Mackerras <paulus@samba.org>2006-03-08 13:24:22 +1100
committerPaul Mackerras <paulus@samba.org>2006-03-08 13:24:22 +1100
commit1bd79336a426c5e4f3bab142407059ceb12cadf9 (patch)
treedd8767b0ab3ce310c7df049822100e3838b37a97 /arch/ppc/kernel
parentab1b55e21f6977e420341727e9f4a50691057b5e (diff)
downloadlwn-1bd79336a426c5e4f3bab142407059ceb12cadf9.tar.gz
lwn-1bd79336a426c5e4f3bab142407059ceb12cadf9.zip
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: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/ppc/kernel')
-rw-r--r--arch/ppc/kernel/asm-offsets.c1
-rw-r--r--arch/ppc/kernel/entry.S95
2 files changed, 24 insertions, 72 deletions
diff --git a/arch/ppc/kernel/asm-offsets.c b/arch/ppc/kernel/asm-offsets.c
index 7964bf660e92..77e4dc780f8c 100644
--- a/arch/ppc/kernel/asm-offsets.c
+++ b/arch/ppc/kernel/asm-offsets.c
@@ -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));
diff --git a/arch/ppc/kernel/entry.S b/arch/ppc/kernel/entry.S
index a48b950722a1..3a2815978488 100644
--- a/arch/ppc/kernel/entry.S
+++ b/arch/ppc/kernel/entry.S
@@ -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: