Hi Andy Lutomirski,
Do you have any comment on this patch?
Thank you.
On 2015/2/27 12:19, Wang Nan wrote:
> As early_trap_init() doesn't use IST, replace set_intr_gate_ist() and
> set_system_intr_gate_ist() with their standard counterparts.
>
> set_intr_gate() requires a trace_debug symbol which we don't have and
> won't use. This patch seprates set_intr_gate() into 2 parts, and uses
> base version in early_trap_init().
>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> ---
>
> Hi Andy Lutomirski,
>
> This patch should be less tricky than previous one [1]. I also tried
> to renaming all set_intr_gate(), but it causes too many code changes,
> so I think you will be satisfied with this one.
>
> Thank you!
>
> [1] https://lkml.org/lkml/2015/2/26/770
>
> ---
> arch/x86/include/asm/desc.h | 7 ++++++-
> arch/x86/kernel/traps.c | 20 ++++++++++++--------
> 2 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> index a94b82e..a0bf89f 100644
> --- a/arch/x86/include/asm/desc.h
> +++ b/arch/x86/include/asm/desc.h
> @@ -376,11 +376,16 @@ static inline void _set_gate(int gate, unsigned type, void *addr,
> * Pentium F0 0F bugfix can have resulted in the mapped
> * IDT being write-protected.
> */
> -#define set_intr_gate(n, addr) \
> +#define set_intr_gate_notrace(n, addr) \
> do { \
> BUG_ON((unsigned)n > 0xFF); \
> _set_gate(n, GATE_INTERRUPT, (void *)addr, 0, 0, \
> __KERNEL_CS); \
> + } while (0)
> +
> +#define set_intr_gate(n, addr) \
> + do { \
> + set_intr_gate_notrace(n, addr); \
> _trace_set_gate(n, GATE_INTERRUPT, (void *)trace_##addr,\
> 0, 0, __KERNEL_CS); \
> } while (0)
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 4281988..9965bd1 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -926,16 +926,20 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
> void __init early_trap_init(void)
> {
> /*
> - * Don't set ist to DEBUG_STACK as it doesn't work until TSS is
> - * ready in cpu_init() <-- trap_init(). Before trap_init(), CPU
> - * runs at ring 0 so it is impossible to hit an invalid stack.
> - * Using the original stack works well enough at this early
> - * stage. DEBUG_STACK will be equipped after cpu_init() in
> + * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
> + * is ready in cpu_init() <-- trap_init(). Before trap_init(),
> + * CPU runs at ring 0 so it is impossible to hit an invalid
> + * stack. Using the original stack works well enough at this
> + * early stage. DEBUG_STACK will be equipped after cpu_init() in
> * trap_init().
> + *
> + * We don't need to set trace_idt_table like set_intr_gate(),
> + * since we don't have trace_debug and it will be reset to
> + * 'debug' in trap_init() by set_intr_gate_ist().
> */
> - set_intr_gate_ist(X86_TRAP_DB, &debug, 0);
> + set_intr_gate_notrace(X86_TRAP_DB, debug);
> /* int3 can be called from all */
> - set_system_intr_gate_ist(X86_TRAP_BP, &int3, 0);
> + set_system_intr_gate(X86_TRAP_BP, &int3);
> #ifdef CONFIG_X86_32
> set_intr_gate(X86_TRAP_PF, page_fault);
> #endif
> @@ -1015,7 +1019,7 @@ void __init trap_init(void)
>
> /*
> * X86_TRAP_DB and X86_TRAP_BP have been set
> - * in early_trap_init(). However, DEBUG_STACK works only after
> + * in early_trap_init(). However, ITS works only after
> * cpu_init() loads TSS. See comments in early_trap_init().
> */
> set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
>
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