Messages in this thread Patch in this message | | | Date | Fri, 4 May 2018 11:25:57 -0500 | From | Josh Poimboeuf <> | Subject | Re: perf: fuzzer causes stack going in wrong direction warnings |
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On Fri, May 04, 2018 at 10:35:53AM -0400, Vince Weaver wrote: > On Wed, 2 May 2018, Josh Poimboeuf wrote: > > > After looking closer, I realized that at least some of these warnings > > are due to bad unwind hints in the entry code. Can you try this patch > > instead of the last one? > > with just this new patch applied I still get warnings such as this: > > [ 469.436218] WARNING: can't dereference registers at 00000000886d9235 for ip apic_timer_interrupt+0xa/0x20 > [ 790.499655] WARNING: stack recursion on stack type 2 > [ 790.907092] WARNING: stack going in the wrong direction? ip=native_sched_clock+0x9/0x90 > [ 3632.876656] WARNING: can't dereference iret registers at 000000001754e5aa for ip nmi_restore+0x16/0x2b > [ 3650.161250] WARNING: missing regs for base reg R10 at ip native_sched_clock+0xd/0x90
The 'nmi_restore' warning points to a bug in my patch, but the others are head scratchers. Here's a patch which combines the first two patches, plus improves the existing warnings a bit. Can you try it?
Also, any tips for reproducing this locally? I cloned the perf fuzzer github. Is it as simple as just "make" and "./run_tests.sh"?
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index be63330c5511..73f5d4c10304 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -165,6 +165,7 @@ For 32-bit we have the following conventions - kernel is built with .endif popq %rdx popq %rsi + UNWIND_HINT_IRET_REGS offset=16 .if \pop_rdi popq %rdi .endif diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 805f52703ee3..2908ed2ef698 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -306,7 +306,6 @@ GLOBAL(entry_SYSCALL_64_after_hwframe) */ syscall_return_via_sysret: /* rcx and r11 are already restored (see code above) */ - UNWIND_HINT_EMPTY POP_REGS pop_rdi=0 skip_r11rcx=1 /* @@ -315,6 +314,7 @@ syscall_return_via_sysret: */ movq %rsp, %rdi movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp + UNWIND_HINT_EMPTY pushq RSP-RDI(%rdi) /* RSP */ pushq (%rdi) /* RDI */ @@ -666,6 +666,7 @@ GLOBAL(swapgs_restore_regs_and_return_to_usermode) */ movq %rsp, %rdi movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp + UNWIND_HINT_EMPTY /* Copy the IRET frame to the trampoline stack. */ pushq 6*8(%rdi) /* SS */ diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 563e28d14f2c..d8dbf7c3c2f1 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -137,7 +137,9 @@ int get_stack_info(unsigned long *stack, struct task_struct *task, */ if (visit_mask) { if (*visit_mask & (1UL << info->type)) { - printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type); + if (task == current) + printk_deferred(KERN_WARNING "WARNING: stack recursion on stack type %d\n", + info->type); goto unknown; } *visit_mask |= 1UL << info->type; diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index feb28fee6cea..1324ffdb861d 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -7,7 +7,14 @@ #include <asm/orc_lookup.h> #define orc_warn(fmt, ...) \ - printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__) + printk_deferred(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__) + +#define orc_warn_current(fmt, ...) \ +({ \ + if (state->task == current) \ + printk_deferred(KERN_WARNING "WARNING: " fmt, \ + ##__VA_ARGS__); \ +}) extern int __start_orc_unwind_ip[]; extern int __stop_orc_unwind_ip[]; @@ -400,8 +407,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_REG_R10: if (!state->regs || !state->full_regs) { - orc_warn("missing regs for base reg R10 at ip %pB\n", - (void *)state->ip); + orc_warn_current("missing regs for base reg R10 at ip %pB\n", + (void *)state->ip); goto done; } sp = state->regs->r10; @@ -409,8 +416,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_REG_R13: if (!state->regs || !state->full_regs) { - orc_warn("missing regs for base reg R13 at ip %pB\n", - (void *)state->ip); + orc_warn_current("missing regs for base reg R13 at ip %pB\n", + (void *)state->ip); goto done; } sp = state->regs->r13; @@ -418,8 +425,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_REG_DI: if (!state->regs || !state->full_regs) { - orc_warn("missing regs for base reg DI at ip %pB\n", - (void *)state->ip); + orc_warn_current("missing regs for base reg DI at ip %pB\n", + (void *)state->ip); goto done; } sp = state->regs->di; @@ -427,8 +434,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_REG_DX: if (!state->regs || !state->full_regs) { - orc_warn("missing regs for base reg DX at ip %pB\n", - (void *)state->ip); + orc_warn_current("missing regs for base reg DX at ip %pB\n", + (void *)state->ip); goto done; } sp = state->regs->dx; @@ -463,8 +470,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_TYPE_REGS: if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) { - orc_warn("can't dereference registers at %p for ip %pB\n", - (void *)sp, (void *)orig_ip); + orc_warn_current("can't dereference registers at %p for ip %pB\n", + (void *)sp, (void *)orig_ip); goto done; } @@ -475,8 +482,8 @@ bool unwind_next_frame(struct unwind_state *state) case ORC_TYPE_REGS_IRET: if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) { - orc_warn("can't dereference iret registers at %p for ip %pB\n", - (void *)sp, (void *)orig_ip); + orc_warn_current("can't dereference iret registers at %p for ip %pB\n", + (void *)sp, (void *)orig_ip); goto done; } @@ -518,8 +525,8 @@ bool unwind_next_frame(struct unwind_state *state) if (state->stack_info.type == prev_type && on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) && state->sp <= prev_sp) { - orc_warn("stack going in the wrong direction? ip=%pB\n", - (void *)orig_ip); + orc_warn_current("stack going in the wrong direction? ip=%pB\n", + (void *)orig_ip); goto done; } diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 92b6a2c21631..d66f14bb6c50 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1239,7 +1239,7 @@ static int update_insn_state_regs(struct instruction *insn, struct insn_state *s struct cfi_reg *cfa = &state->cfa; struct stack_op *op = &insn->stack_op; - if (cfa->base != CFI_SP) + if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT) return 0; /* push */
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