@@ -574,6 +574,32 @@ syscall_exit_work:
bl do_syscall_trace_leave
b ret_from_except_full
+ /*
+ * System call was called from kernel. We get here with SRR1 in r9.
+ * Mark the exception as recoverable once we have retrieved SRR0,
+ * trap a warning and return ENOSYS with CR[SO] set.
+ */
+ .globl ret_from_kernel_syscall
+ret_from_kernel_syscall:
+ mfspr r11, SPRN_SRR0
+#if !defined(CONFIG_4xx) && !defined(CONFIG_BOOKE)
+ LOAD_REG_IMMEDIATE(r12, MSR_KERNEL & ~(MSR_IR|MSR_DR))
+ MTMSRD(r12)
+#endif
+
+0: trap
+ EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
+
+ li r3, ENOSYS
+ crset so
+#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)
+ mtspr SPRN_NRI, r0
+#endif
+ mtspr SPRN_SRR1, r9
+ mtspr SPRN_SRR0, r11
+ SYNC
+ RFI
+
/*
* The fork/clone functions need to copy the full register set into
* the child process. Therefore we need to save all the nonvolatile
@@ -112,13 +112,17 @@
.macro SYSCALL_ENTRY trapno
mfspr r12,SPRN_SPRG_THREAD
#ifdef CONFIG_VMAP_STACK
- mfspr r9, SPRN_SRR0
- mfspr r11, SPRN_SRR1
- stw r9, SRR0(r12)
- stw r11, SRR1(r12)
+ mfspr r11, SPRN_SRR0
+ mfspr r9, SPRN_SRR1
+ stw r11, SRR0(r12)
+ stw r9, SRR1(r12)
+#else
+ mfspr r9, SPRN_SRR1
#endif
mfcr r10
+ andi. r11, r9, MSR_PR
lwz r11,TASK_STACK-THREAD(r12)
+ beq- 99f
rlwinm r10,r10,0,4,2 /* Clear SO bit in CR */
addi r11, r11, THREAD_SIZE - INT_FRAME_SIZE
#ifdef CONFIG_VMAP_STACK
@@ -128,15 +132,14 @@
#endif
tovirt_vmstack r12, r12
tophys_novmstack r11, r11
- mflr r9
stw r10,_CCR(r11) /* save registers */
- stw r9, _LINK(r11)
+ mflr r10
+ stw r10, _LINK(r11)
#ifdef CONFIG_VMAP_STACK
lwz r10, SRR0(r12)
lwz r9, SRR1(r12)
#else
mfspr r10,SPRN_SRR0
- mfspr r9,SPRN_SRR1
#endif
stw r1,GPR1(r11)
stw r1,0(r11)
@@ -209,6 +212,7 @@
mtspr SPRN_SRR0,r11
SYNC
RFI /* jump to handler, enable MMU */
+99: b ret_from_kernel_syscall
.endm
.macro save_dar_dsisr_on_stack reg1, reg2, sp
@@ -104,16 +104,18 @@ FTR_SECTION_ELSE
#ifdef CONFIG_KVM_BOOKE_HV
ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
#endif
+ mfspr r9, SPRN_SRR1
BOOKE_CLEAR_BTB(r11)
+ andi. r11, r9, MSR_PR
lwz r11, TASK_STACK - THREAD(r10)
rlwinm r12,r12,0,4,2 /* Clear SO bit in CR */
+ beq- 99f
ALLOC_STACK_FRAME(r11, THREAD_SIZE - INT_FRAME_SIZE)
stw r12, _CCR(r11) /* save various registers */
mflr r12
stw r12,_LINK(r11)
mfspr r12,SPRN_SRR0
stw r1, GPR1(r11)
- mfspr r9,SPRN_SRR1
stw r1, 0(r11)
mr r1, r11
stw r12,_NIP(r11)
@@ -176,6 +178,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
mtspr SPRN_SRR0,r11
SYNC
RFI /* jump to handler, enable MMU */
+99: b ret_from_kernel_syscall
.endm
/* To handle the additional exception priority levels on 40x and Book-E
Since commit b86fb88855ea ("powerpc/32: implement fast entry for syscalls on non BOOKE") and commit 1a4b739bbb4f ("powerpc/32: implement fast entry for syscalls on BOOKE"), syscalls from kernel are unexpected and can have catastrophic consequences as it will destroy the kernel stack. Test MSR_PR on syscall entry. In case syscall is from kernel, emit a warning and return ENOSYS error. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- v2: Rebased on powerpc/next-test, ie on top of VMAP_STACK series --- arch/powerpc/kernel/entry_32.S | 26 ++++++++++++++++++++++++++ arch/powerpc/kernel/head_32.h | 18 +++++++++++------- arch/powerpc/kernel/head_booke.h | 5 ++++- 3 files changed, 41 insertions(+), 8 deletions(-)