From fd501d4f0399700011acde486576c7c1eb8e7a61 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 29 May 2020 23:27:38 +0200 Subject: x86/entry: Remove DBn stacks Both #DB itself, as all other IST users (NMI, #MC) now clear DR7 on entry. Combined with not allowing breakpoints on entry/noinstr/NOKPROBE text and no single step (EFLAGS.TF) inside the #DB handler should guarantee no nested #DB. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200529213321.303027161@infradead.org --- arch/x86/kernel/asm-offsets_64.c | 3 --- arch/x86/kernel/dumpstack_64.c | 7 ++----- 2 files changed, 2 insertions(+), 8 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index c2a47016f243..828be792231e 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -57,9 +57,6 @@ int main(void) BLANK(); #undef ENTRY - OFFSET(TSS_ist, tss_struct, x86_tss.ist); - DEFINE(DB_STACK_OFFSET, offsetof(struct cea_exception_stacks, DB_stack) - - offsetof(struct cea_exception_stacks, DB1_stack)); BLANK(); #ifdef CONFIG_STACKPROTECTOR diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 460ae7f66818..4a94d38cd141 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -22,15 +22,13 @@ static const char * const exception_stack_names[] = { [ ESTACK_DF ] = "#DF", [ ESTACK_NMI ] = "NMI", - [ ESTACK_DB2 ] = "#DB2", - [ ESTACK_DB1 ] = "#DB1", [ ESTACK_DB ] = "#DB", [ ESTACK_MCE ] = "#MC", }; const char *stack_type_name(enum stack_type type) { - BUILD_BUG_ON(N_EXCEPTION_STACKS != 6); + BUILD_BUG_ON(N_EXCEPTION_STACKS != 4); if (type == STACK_TYPE_IRQ) return "IRQ"; @@ -79,7 +77,6 @@ static const struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = { EPAGERANGE(DF), EPAGERANGE(NMI), - EPAGERANGE(DB1), EPAGERANGE(DB), EPAGERANGE(MCE), }; @@ -91,7 +88,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info) struct pt_regs *regs; unsigned int k; - BUILD_BUG_ON(N_EXCEPTION_STACKS != 6); + BUILD_BUG_ON(N_EXCEPTION_STACKS != 4); begin = (unsigned long)__this_cpu_read(cea_exception_stacks); /* -- cgit v1.2.3