From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v2 25/52] powerpc/64s/exception: remove bad stack branch
Date: Thu, 20 Jun 2019 15:14:32 +1000 [thread overview]
Message-ID: <20190620051459.29573-26-npiggin@gmail.com> (raw)
In-Reply-To: <20190620051459.29573-1-npiggin@gmail.com>
The bad stack test in interrupt handlers has a few problems. For
performance it is taken in the common case, which is a fetch bubble
and a waste of i-cache.
For code development and maintainence, it requires yet another stack
frame setup routine, and that constrains all exception handlers to
follow the same register save pattern which inhibits future
optimisation.
Remove the test/branch and replace it with a trap. Teach the program
check handler to use the emergency stack for this case.
This does not result in quite so nice a message, however the SRR0 and
SRR1 of the crashed interrupt can be seen in r11 and r12, as is the
original r1 (adjusted by INT_FRAME_SIZE). These are the most important
parts to debugging the issue.
The original r9-12 and cr0 is lost, which is the main downside.
kernel BUG at linux/arch/powerpc/kernel/exceptions-64s.S:847!
Oops: Exception in kernel mode, sig: 5 [#1]
BE SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted
NIP: c000000000009108 LR: c000000000cadbcc CTR: c0000000000090f0
REGS: c0000000fffcbd70 TRAP: 0700 Not tainted
MSR: 9000000000021032 <SF,HV,ME,IR,DR,RI> CR: 28222448 XER: 20040000
CFAR: c000000000009100 IRQMASK: 0
GPR00: 000000000000003d fffffffffffffd00 c0000000018cfb00 c0000000f02b3166
GPR04: fffffffffffffffd 0000000000000007 fffffffffffffffb 0000000000000030
GPR08: 0000000000000037 0000000028222448 0000000000000000 c000000000ca8de0
GPR12: 9000000002009032 c000000001ae0000 c000000000010a00 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: c0000000f00322c0 c000000000f85200 0000000000000004 ffffffffffffffff
GPR24: fffffffffffffffe 0000000000000000 0000000000000000 000000000000000a
GPR28: 0000000000000000 0000000000000000 c0000000f02b391c c0000000f02b3167
NIP [c000000000009108] decrementer_common+0x18/0x160
LR [c000000000cadbcc] .vsnprintf+0x3ec/0x4f0
Call Trace:
Instruction dump:
996d098a 994d098b 38610070 480246ed 48005518 60000000 38200000 718a4000
7c2a0b78 3821fd00 41c20008 e82d0970 <0981fd00> f92101a0 f9610170 f9810178
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/exception-64s.h | 7 --
arch/powerpc/include/asm/paca.h | 2 +
arch/powerpc/kernel/asm-offsets.c | 2 +
arch/powerpc/kernel/exceptions-64s.S | 95 ++++--------------------
arch/powerpc/xmon/xmon.c | 2 +
5 files changed, 22 insertions(+), 86 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index dc6a5ccac965..79e5ac87c029 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -55,13 +55,6 @@
*/
#define MAX_MCE_DEPTH 4
-/*
- * EX_R3 is only used by the bad_stack handler. bad_stack reloads and
- * saves DAR from SPRN_DAR, and EX_DAR is not used. So EX_R3 can overlap
- * with EX_DAR.
- */
-#define EX_R3 EX_DAR
-
#ifdef __ASSEMBLY__
#define STF_ENTRY_BARRIER_SLOT \
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 9bd2326bef6f..e3cc9eb9204d 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -166,7 +166,9 @@ struct paca_struct {
u64 kstack; /* Saved Kernel stack addr */
u64 saved_r1; /* r1 save for RTAS calls or PM or EE=0 */
u64 saved_msr; /* MSR saved here by enter_rtas */
+#ifdef CONFIG_PPC_BOOK3E
u16 trap_save; /* Used when bad stack is encountered */
+#endif
u8 irq_soft_mask; /* mask for irq soft masking */
u8 irq_happened; /* irq happened while soft-disabled */
u8 irq_work_pending; /* IRQ_WORK interrupt while soft-disable */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 31dc7e64cbfc..4ccb6b3a7fbd 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -266,7 +266,9 @@ int main(void)
OFFSET(ACCOUNT_STARTTIME_USER, paca_struct, accounting.starttime_user);
OFFSET(ACCOUNT_USER_TIME, paca_struct, accounting.utime);
OFFSET(ACCOUNT_SYSTEM_TIME, paca_struct, accounting.stime);
+#ifdef CONFIG_PPC_BOOK3E
OFFSET(PACA_TRAP_SAVE, paca_struct, trap_save);
+#endif
OFFSET(PACA_SPRG_VDSO, paca_struct, sprg_vdso);
#else /* CONFIG_PPC64 */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 0a2b4e8b02b0..6c0321e128da 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -343,14 +343,8 @@ END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,948)
subi r1,r1,INT_FRAME_SIZE; /* alloc frame on kernel stack */ \
beq- 1f; \
ld r1,PACAKSAVE(r13); /* kernel stack to use */ \
-1: cmpdi cr1,r1,-INT_FRAME_SIZE; /* check if r1 is in userspace */ \
- blt+ cr1,3f; /* abort if it is */ \
- li r1,(n); /* will be reloaded later */ \
- sth r1,PACA_TRAP_SAVE(r13); \
- std r3,area+EX_R3(r13); \
- addi r3,r13,area; /* r3 -> where regs are saved*/ \
- RESTORE_CTR(r1, area); \
- b bad_stack; \
+1: tdgei r1,-INT_FRAME_SIZE; /* trap if r1 is in userspace */ \
+ EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,0; \
3: EXCEPTION_PROLOG_COMMON_1(); \
kuap_save_amr_and_lock r9, r10, cr1, cr0; \
beq 4f; /* if from kernel mode */ \
@@ -1489,21 +1483,25 @@ EXC_COMMON_BEGIN(program_check_common)
* we switch to the emergency stack if we're taking a TM Bad Thing from
* the kernel.
*/
- li r10,MSR_PR /* Build a mask of MSR_PR .. */
- oris r10,r10,0x200000@h /* .. and SRR1_PROGTM */
- and r10,r10,r12 /* Mask SRR1 with that. */
- srdi r10,r10,8 /* Shift it so we can compare */
- cmpldi r10,(0x200000 >> 8) /* .. with an immediate. */
- bne 1f /* If != go to normal path. */
-
- /* SRR1 had PR=0 and SRR1_PROGTM=1, so use the emergency stack */
- andi. r10,r12,MSR_PR; /* Set CR0 correctly for label */
+
+ andi. r10,r12,MSR_PR
+ bne 2f /* If userspace, go normal path */
+
+ andis. r10,r12,(SRR1_PROGTM)@h
+ bne 1f /* If TM, emergency */
+
+ cmpdi r1,-INT_FRAME_SIZE /* check if r1 is in userspace */
+ blt 2f /* normal path if not */
+
+ /* Use the emergency stack */
+1: andi. r10,r12,MSR_PR /* Set CR0 correctly for label */
/* 3 in EXCEPTION_PROLOG_COMMON */
mr r10,r1 /* Save r1 */
ld r1,PACAEMERGSP(r13) /* Use emergency stack */
subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
b 3f /* Jump into the macro !! */
-1: EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
+2:
+ EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
bl save_nvgprs
RECONCILE_IRQ_STATE(r10, r11)
addi r3,r1,STACK_FRAME_OVERHEAD
@@ -2474,67 +2472,6 @@ handle_dabr_fault:
bl bad_page_fault
b ret_from_except
-/*
- * Here we have detected that the kernel stack pointer is bad.
- * R9 contains the saved CR, r13 points to the paca,
- * r10 contains the (bad) kernel stack pointer,
- * r11 and r12 contain the saved SRR0 and SRR1.
- * We switch to using an emergency stack, save the registers there,
- * and call kernel_bad_stack(), which panics.
- */
-bad_stack:
- ld r1,PACAEMERGSP(r13)
- subi r1,r1,64+INT_FRAME_SIZE
- std r9,_CCR(r1)
- std r10,GPR1(r1)
- std r11,_NIP(r1)
- std r12,_MSR(r1)
- mfspr r11,SPRN_DAR
- mfspr r12,SPRN_DSISR
- std r11,_DAR(r1)
- std r12,_DSISR(r1)
- mflr r10
- mfctr r11
- mfxer r12
- std r10,_LINK(r1)
- std r11,_CTR(r1)
- std r12,_XER(r1)
- SAVE_GPR(0,r1)
- SAVE_GPR(2,r1)
- ld r10,EX_R3(r3)
- std r10,GPR3(r1)
- SAVE_GPR(4,r1)
- SAVE_4GPRS(5,r1)
- ld r9,EX_R9(r3)
- ld r10,EX_R10(r3)
- SAVE_2GPRS(9,r1)
- ld r9,EX_R11(r3)
- ld r10,EX_R12(r3)
- ld r11,EX_R13(r3)
- std r9,GPR11(r1)
- std r10,GPR12(r1)
- std r11,GPR13(r1)
-BEGIN_FTR_SECTION
- ld r10,EX_CFAR(r3)
- std r10,ORIG_GPR3(r1)
-END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
- SAVE_8GPRS(14,r1)
- SAVE_10GPRS(22,r1)
- lhz r12,PACA_TRAP_SAVE(r13)
- std r12,_TRAP(r1)
- addi r11,r1,INT_FRAME_SIZE
- std r11,0(r1)
- li r12,0
- std r12,0(r11)
- ld r2,PACATOC(r13)
- ld r11,exception_marker@toc(r2)
- std r12,RESULT(r1)
- std r11,STACK_FRAME_OVERHEAD-16(r1)
-1: addi r3,r1,STACK_FRAME_OVERHEAD
- bl kernel_bad_stack
- b 1b
-_ASM_NOKPROBE_SYMBOL(bad_stack);
-
/*
* When doorbell is triggered from system reset wakeup, the message is
* not cleared, so it would fire again when EE is enabled.
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index d0620d762a5a..41c91f17e408 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -2448,7 +2448,9 @@ static void dump_one_paca(int cpu)
DUMP(p, canary, "%#-*lx");
#endif
DUMP(p, saved_r1, "%#-*llx");
+#ifdef CONFIG_PPC_BOOK3E
DUMP(p, trap_save, "%#-*x");
+#endif
DUMP(p, irq_soft_mask, "%#-*x");
DUMP(p, irq_happened, "%#-*x");
#ifdef CONFIG_MMIOWB
--
2.20.1
next prev parent reply other threads:[~2019-06-20 6:07 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 5:14 [PATCH v2 00/52] powerpc/64s interrupt handler cleanups, gasification Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 01/52] powerpc/64s/exception: fix line wrap and semicolon inconsistencies in macros Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 02/52] powerpc/64s/exception: remove H concatenation for EXC_HV variants Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 03/52] powerpc/64s/exception: consolidate EXCEPTION_PROLOG_2 with _NORI variant Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 04/52] powerpc/64s/exception: move and tidy EXCEPTION_PROLOG_2 variants Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 05/52] powerpc/64s/exception: fix sreset KVM test code Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 06/52] powerpc/64s/exception: remove the "extra" macro parameter Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 07/52] powerpc/64s/exception: consolidate maskable and non-maskable prologs Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 08/52] powerpc/64s/exception: merge KVM handler and skip variants Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 09/52] powerpc/64s/exception: KVM handler can set the HSRR trap bit Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 10/52] powerpc/64s/exception: Make EXCEPTION_PROLOG_0 a gas macro for consistency with others Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 11/52] powerpc/64s/exception: Move EXCEPTION_COMMON handler and return branches into callers Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 12/52] powerpc/64s/exception: Move EXCEPTION_COMMON additions " Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 13/52] powerpc/64s/exception: unwind exception-64s.h macros Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 14/52] powerpc/64s/exception: improve 0x500 handler code Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 15/52] powerpc/64s/exception: move EXCEPTION_PROLOG_2* to a more logical place Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 16/52] powerpc/64s/exception: remove STD_EXCEPTION_COMMON variants Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 17/52] powerpc/64s/exception: move KVM related code together Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 18/52] powerpc/64s/exception: move exception-64s.h code to exception-64s.S where it is used Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 19/52] powerpc/64s/exception: move head-64.h " Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 20/52] powerpc/64s/exception: remove __BRANCH_TO_KVM Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 21/52] powerpc/64s/exception: remove unused BRANCH_TO_COMMON Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 22/52] powerpc/64s/exception: use a gas macro for system call handler code Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 23/52] powerpc/64s/exception: fix indenting irregularities Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 24/52] powerpc/64s/exception: generate regs clear instructions using .rept Nicholas Piggin
2019-06-20 5:14 ` Nicholas Piggin [this message]
2019-06-20 5:14 ` [PATCH v2 26/52] powerpc/64s/exception: remove pointless EXCEPTION_PROLOG macro indirection Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 27/52] powerpc/64s/exception: move paca save area offsets into exception-64s.S Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 28/52] powerpc/64s/exception: clean up system call entry Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 29/52] powerpc/64s/exception: avoid SPR RAW scoreboard stall in real mode entry Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 30/52] powerpc/64s/exception: optimise system_reset for idle, clean up non-idle case Nicholas Piggin
2019-06-20 5:41 ` Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 31/52] powerpc/64s/exception: mtmsrd L=1 cleanup Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 32/52] powerpc/64s/exception: windup use r9 consistently to restore SPRs Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 33/52] powerpc/64s/exception: move machine check windup in_mce handling Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 34/52] powerpc/64s/exception: simplify hmi windup code Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 35/52] powerpc/64s/exception: shuffle windup code around Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 36/52] powerpc/64s/exception: use common macro for windup Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 37/52] powerpc/64s/exception: add dar and dsisr options to exception macro Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 38/52] powerpc/64s/exception: machine check use standard macros to save dar/dsisr Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 39/52] powerpc/64s/exception: denorm handler use standard scratch save macro Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 40/52] powerpc/64s/exception: move SET_SCRATCH0 into EXCEPTION_PROLOG_0 Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 41/52] powerpc/tm: update comment about interrupt re-entrancy Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 42/52] powerpc/64s/exception: machine check fwnmi does not trigger when in HV mode Nicholas Piggin
2019-06-20 9:26 ` Mahesh Jagannath Salgaonkar
2019-06-20 9:50 ` Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 43/52] powerpc/64s/exception: machine check early only runs " Nicholas Piggin
2019-06-20 9:53 ` Mahesh J Salgaonkar
2019-06-20 10:16 ` Nicholas Piggin
2019-06-20 10:57 ` Mahesh Jagannath Salgaonkar
2019-06-20 5:14 ` [PATCH v2 44/52] powerpc/64s/exception: separate pseries and powernv mce delivery paths Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 45/52] powerpc/64s/exception: machine check windup restore cfar for host delivery Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 46/52] powerpc/64s/exception: fix machine check early should not set AMR Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 47/52] powerpc/64s/exception: machine check restructure handler to be more regular Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 48/52] powerpc/64s/exception: simplify machine check early path Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 49/52] powerpc/64s/exceptions: machine check move unrecoverable handling out of line Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 50/52] powerpc/64s/exception: untangle early machine check handler Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 51/52] powerpc/64s/exception: machine check improve branch labels Nicholas Piggin
2019-06-20 5:14 ` [PATCH v2 52/52] powerpc/64s/exception: add missing branch to self after RFI Nicholas Piggin
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