diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-05-29 23:27:38 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-11 15:15:23 +0200 |
| commit | fd501d4f0399700011acde486576c7c1eb8e7a61 (patch) | |
| tree | 8c5c09d3cb0b5aa0f249c6627dc4298354f21442 /arch/x86/entry/entry_64.S | |
| parent | f9912ada82862df341b3e86864cbd532d0d24b84 (diff) | |
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) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.303027161@infradead.org
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 17 |
1 files changed, 0 insertions, 17 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 265ff97b3961..8ecaeee53653 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -396,11 +396,6 @@ SYM_CODE_END(\asmsym) idtentry \vector asm_\cfunc \cfunc has_error_code=0 .endm -/* - * MCE and DB exceptions - */ -#define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + (x) * 8) - /** * idtentry_mce_db - Macro to generate entry stubs for #MC and #DB * @vector: Vector number @@ -416,10 +411,6 @@ SYM_CODE_END(\asmsym) * If hits in kernel mode then it needs to go through the paranoid * entry as the exception can hit any random state. No preemption * check on exit to keep the paranoid path simple. - * - * If the trap is #DB then the interrupt stack entry in the IST is - * moved to the second stack, so a potential recursion will have a - * fresh IST. */ .macro idtentry_mce_db vector asmsym cfunc SYM_CODE_START(\asmsym) @@ -445,16 +436,8 @@ SYM_CODE_START(\asmsym) movq %rsp, %rdi /* pt_regs pointer */ - .if \vector == X86_TRAP_DB - subq $DB_STACK_OFFSET, CPU_TSS_IST(IST_INDEX_DB) - .endif - call \cfunc - .if \vector == X86_TRAP_DB - addq $DB_STACK_OFFSET, CPU_TSS_IST(IST_INDEX_DB) - .endif - jmp paranoid_exit /* Switch to the regular task stack and use the noist entry point */ |