Messages in this thread Patch in this message | | | Date | Tue, 12 May 2020 23:01:35 +0200 | From | Thomas Gleixner <> | Subject | [patch V5 36/38] x86/entry/64: Remove TRACE_IRQS_*_DEBUG |
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From: Peter Zijlstra <peterz@infradead.org>
Since INT3/#BP no longer runs on an IST, this workaround is no longer required.
Tested by running lockdep+ftrace as described in the initial commit:
5963e317b1e9 ("ftrace/x86: Do not change stacks in DEBUG when calling lockdep")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
--- arch/x86/entry/entry_64.S | 48 ++-------------------------------------------- 1 file changed, 3 insertions(+), 45 deletions(-)
--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -68,44 +68,6 @@ SYM_CODE_END(native_usergs_sysret64) .endm /* - * When dynamic function tracer is enabled it will add a breakpoint - * to all locations that it is about to modify, sync CPUs, update - * all the code, sync CPUs, then remove the breakpoints. In this time - * if lockdep is enabled, it might jump back into the debug handler - * outside the updating of the IST protection. (TRACE_IRQS_ON/OFF). - * - * We need to change the IDT table before calling TRACE_IRQS_ON/OFF to - * make sure the stack pointer does not get reset back to the top - * of the debug stack, and instead just reuses the current stack. - */ -#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_TRACE_IRQFLAGS) - -.macro TRACE_IRQS_OFF_DEBUG - call debug_stack_set_zero - TRACE_IRQS_OFF - call debug_stack_reset -.endm - -.macro TRACE_IRQS_ON_DEBUG - call debug_stack_set_zero - TRACE_IRQS_ON - call debug_stack_reset -.endm - -.macro TRACE_IRQS_IRETQ_DEBUG - btl $9, EFLAGS(%rsp) /* interrupts off? */ - jnc 1f - TRACE_IRQS_ON_DEBUG -1: -.endm - -#else -# define TRACE_IRQS_OFF_DEBUG TRACE_IRQS_OFF -# define TRACE_IRQS_ON_DEBUG TRACE_IRQS_ON -# define TRACE_IRQS_IRETQ_DEBUG TRACE_IRQS_IRETQ -#endif - -/* * 64-bit SYSCALL instruction entry. Up to 6 arguments in registers. * * This is the only entry point used for 64-bit system calls. The @@ -500,11 +462,7 @@ SYM_CODE_START(\asmsym) UNWIND_HINT_REGS - .if \vector == X86_TRAP_DB - TRACE_IRQS_OFF_DEBUG - .else - TRACE_IRQS_OFF - .endif + TRACE_IRQS_OFF movq %rsp, %rdi /* pt_regs pointer */ @@ -924,7 +882,7 @@ SYM_CODE_END(paranoid_entry) SYM_CODE_START_LOCAL(paranoid_exit) UNWIND_HINT_REGS DISABLE_INTERRUPTS(CLBR_ANY) - TRACE_IRQS_OFF_DEBUG + TRACE_IRQS_OFF testl %ebx, %ebx /* swapgs needed? */ jnz .Lparanoid_exit_no_swapgs TRACE_IRQS_IRETQ @@ -933,7 +891,7 @@ SYM_CODE_START_LOCAL(paranoid_exit) SWAPGS_UNSAFE_STACK jmp restore_regs_and_return_to_kernel .Lparanoid_exit_no_swapgs: - TRACE_IRQS_IRETQ_DEBUG + TRACE_IRQS_IRETQ /* Always restore stashed CR3 value (see paranoid_entry) */ RESTORE_CR3 scratch_reg=%rbx save_reg=%r14 jmp restore_regs_and_return_to_kernel
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