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| author | Peter Zijlstra <peterz@infradead.org> | 2020-05-29 23:27:33 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-11 15:15:21 +0200 |
| commit | e1de11d4d1a64ac1b90b9833f1a3629dae18facb (patch) | |
| tree | 0018983a29a3b2b285805eefe8151a9ca335698c | |
| parent | fdef24dfccb7be06e6ebe11d6c6c56987421870f (diff) | |
| download | linux-e1de11d4d1a64ac1b90b9833f1a3629dae18facb.tar.gz | |
x86/entry: Introduce local_db_{save,restore}()
In order to allow other exceptions than #DB to disable breakpoints, provide common helpers. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200529213321.012060983@infradead.org
| -rw-r--r-- | arch/x86/include/asm/debugreg.h | 30 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 18 |
2 files changed, 32 insertions, 16 deletions
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 1a8609a15856..4ef8690be8a7 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -113,6 +113,36 @@ static inline void debug_stack_usage_inc(void) { } static inline void debug_stack_usage_dec(void) { } #endif /* X86_64 */ +static __always_inline unsigned long local_db_save(void) +{ + unsigned long dr7; + + get_debugreg(dr7, 7); + dr7 &= ~0x400; /* architecturally set bit */ + if (dr7) + set_debugreg(0, 7); + /* + * Ensure the compiler doesn't lower the above statements into + * the critical section; disabling breakpoints late would not + * be good. + */ + barrier(); + + return dr7; +} + +static __always_inline void local_db_restore(unsigned long dr7) +{ + /* + * Ensure the compiler doesn't raise this statement into + * the critical section; enabling breakpoints early would + * not be good. + */ + barrier(); + if (dr7) + set_debugreg(dr7, 7); +} + #ifdef CONFIG_CPU_SUP_AMD extern void set_dr_addr_mask(unsigned long mask, int dr); #else diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 50fb9cd5be97..bcb9dd961c6d 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -727,15 +727,7 @@ static __always_inline void debug_enter(unsigned long *dr6, unsigned long *dr7) * Entry text is excluded for HW_BP_X and cpu_entry_area, which * includes the entry stack is excluded for everything. */ - get_debugreg(*dr7, 7); - set_debugreg(0, 7); - - /* - * Ensure the compiler doesn't lower the above statements into - * the critical section; disabling breakpoints late would not - * be good. - */ - barrier(); + *dr7 = local_db_save(); /* * The Intel SDM says: @@ -756,13 +748,7 @@ static __always_inline void debug_enter(unsigned long *dr6, unsigned long *dr7) static __always_inline void debug_exit(unsigned long dr7) { - /* - * Ensure the compiler doesn't raise this statement into - * the critical section; enabling breakpoints early would - * not be good. - */ - barrier(); - set_debugreg(dr7, 7); + local_db_restore(dr7); } /* |