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author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-07-20 09:39:11 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-07-20 09:39:11 +0200 |
commit | 6f2c6599ba70da7ca9603f8026c4e3cdc273ee02 (patch) | |
tree | 88228298182133d9522be62c8cb3eecfcb595d49 /arch/x86/kernel/traps.c | |
parent | ea1be1e59b19017e61aa357d524b743ba5602d3c (diff) | |
parent | ba47d845d715a010f7b51f6f89bae32845e6acb7 (diff) | |
download | linux-stable-6f2c6599ba70da7ca9603f8026c4e3cdc273ee02.tar.gz linux-stable-6f2c6599ba70da7ca9603f8026c4e3cdc273ee02.tar.bz2 linux-stable-6f2c6599ba70da7ca9603f8026c4e3cdc273ee02.zip |
Merge 5.8-rc6 into tty-next
We need the serial/tty fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r-- | arch/x86/kernel/traps.c | 94 |
1 files changed, 56 insertions, 38 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index f9727b96961f..b7cb3e0716f7 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -84,17 +84,16 @@ static inline void cond_local_irq_disable(struct pt_regs *regs) local_irq_disable(); } -int is_valid_bugaddr(unsigned long addr) +__always_inline int is_valid_bugaddr(unsigned long addr) { - unsigned short ud; - if (addr < TASK_SIZE_MAX) return 0; - if (get_kernel_nofault(ud, (unsigned short *)addr)) - return 0; - - return ud == INSN_UD0 || ud == INSN_UD2; + /* + * We got #UD, if the text isn't readable we'd have gotten + * a different exception. + */ + return *(unsigned short *)addr == INSN_UD2; } static nokprobe_inline int @@ -216,40 +215,45 @@ static inline void handle_invalid_op(struct pt_regs *regs) ILL_ILLOPN, error_get_trap_addr(regs)); } -DEFINE_IDTENTRY_RAW(exc_invalid_op) +static noinstr bool handle_bug(struct pt_regs *regs) { - bool rcu_exit; + bool handled = false; + + if (!is_valid_bugaddr(regs->ip)) + return handled; /* - * Handle BUG/WARN like NMIs instead of like normal idtentries: - * if we bugged/warned in a bad RCU context, for example, the last - * thing we want is to BUG/WARN again in the idtentry code, ad - * infinitum. + * All lies, just get the WARN/BUG out. + */ + instrumentation_begin(); + /* + * Since we're emulating a CALL with exceptions, restore the interrupt + * state to what it was at the exception site. */ - if (!user_mode(regs) && is_valid_bugaddr(regs->ip)) { - enum bug_trap_type type; + if (regs->flags & X86_EFLAGS_IF) + raw_local_irq_enable(); + if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) { + regs->ip += LEN_UD2; + handled = true; + } + if (regs->flags & X86_EFLAGS_IF) + raw_local_irq_disable(); + instrumentation_end(); - nmi_enter(); - instrumentation_begin(); - trace_hardirqs_off_finish(); - type = report_bug(regs->ip, regs); - if (regs->flags & X86_EFLAGS_IF) - trace_hardirqs_on_prepare(); - instrumentation_end(); - nmi_exit(); + return handled; +} - if (type == BUG_TRAP_TYPE_WARN) { - /* Skip the ud2. */ - regs->ip += LEN_UD2; - return; - } +DEFINE_IDTENTRY_RAW(exc_invalid_op) +{ + bool rcu_exit; - /* - * Else, if this was a BUG and report_bug returns or if this - * was just a normal #UD, we want to continue onward and - * crash. - */ - } + /* + * We use UD2 as a short encoding for 'CALL __WARN', as such + * handle it before exception entry to avoid recursive WARN + * in case exception entry is the one triggering WARNs. + */ + if (!user_mode(regs) && handle_bug(regs)) + return; rcu_exit = idtentry_enter_cond_rcu(regs); instrumentation_begin(); @@ -299,6 +303,8 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) do_trap(X86_TRAP_AC, SIGBUS, "alignment check", regs, error_code, BUS_ADRALN, NULL); + + local_irq_disable(); } #ifdef CONFIG_VMAP_STACK @@ -691,13 +697,13 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) (struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; /* Copy the IRET target to the temporary storage. */ - memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8); + __memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8); /* Copy the remainder of the stack from the current stack. */ - memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip)); + __memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip)); /* Update the entry stack */ - memcpy(new_stack, &tmp, sizeof(tmp)); + __memcpy(new_stack, &tmp, sizeof(tmp)); BUG_ON(!user_mode(&new_stack->regs)); return new_stack; @@ -866,6 +872,12 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, trace_hardirqs_off_finish(); /* + * If something gets miswired and we end up here for a user mode + * #DB, we will malfunction. + */ + WARN_ON_ONCE(user_mode(regs)); + + /* * Catch SYSENTER with TF set and clear DR_STEP. If this hit a * watchpoint at the same time then that will still be handled. */ @@ -883,6 +895,12 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, static __always_inline void exc_debug_user(struct pt_regs *regs, unsigned long dr6) { + /* + * If something gets miswired and we end up here for a kernel mode + * #DB, we will malfunction. + */ + WARN_ON_ONCE(!user_mode(regs)); + idtentry_enter_user(regs); instrumentation_begin(); @@ -913,7 +931,7 @@ DEFINE_IDTENTRY_DEBUG_USER(exc_debug) } #else /* 32 bit does not have separate entry points. */ -DEFINE_IDTENTRY_DEBUG(exc_debug) +DEFINE_IDTENTRY_RAW(exc_debug) { unsigned long dr6, dr7; |