On Thu, Feb 26, 2015 at 5:12 AM, tip-bot for Wang Nan <tipbot@xxxxxxxxx> wrote: > Commit-ID: b4d8327024637cb2a1f7910dcb5d0ad7a096f473 > Gitweb: http://git.kernel.org/tip/b4d8327024637cb2a1f7910dcb5d0ad7a096f473 > Author: Wang Nan <wangnan0@xxxxxxxxxx> > AuthorDate: Thu, 26 Feb 2015 13:49:39 +0800 > Committer: Ingo Molnar <mingo@xxxxxxxxxx> > CommitDate: Thu, 26 Feb 2015 12:29:20 +0100 > > x86/traps: Enable DEBUG_STACK after cpu_init() for TRAP_DB/BP > > Before this patch early_trap_init() installs DEBUG_STACK for > X86_TRAP_BP and X86_TRAP_DB. However, DEBUG_STACK doesn't work > correctly until cpu_init() <-- trap_init(). > > This patch passes 0 to set_intr_gate_ist() and > set_system_intr_gate_ist() instead of DEBUG_STACK to let it use > same stack as kernel, and installs DEBUG_STACK for them in > trap_init(). > Sorry, I'm late to the party. This patch, while technically correct AFAICT, is really ugly, because the whole point is that it *doesn't* use ist. In other words: > + set_intr_gate_ist(X86_TRAP_DB, &debug, 0); That should be set_intr_gate(X86_TRAP_DB, &debug); > /* int3 can be called from all */ > - set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK); > + set_system_intr_gate_ist(X86_TRAP_BP, &int3, 0); Similarly, this should be set_system_gate. > #ifdef CONFIG_X86_32 > set_intr_gate(X86_TRAP_PF, page_fault); > #endif > @@ -1005,6 +1013,15 @@ void __init trap_init(void) > */ > cpu_init(); > > + /* > + * X86_TRAP_DB and X86_TRAP_BP have been set > + * in early_trap_init(). However, DEBUG_STACK works only after > + * cpu_init() loads TSS. See comments in early_trap_init(). It's not that DEBUG_STACK only works after the TSS is loaded; it's that the IST mechanism only works after TSS is loaded. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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