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SubjectRe: [PATCH kvm-unit-tests] x86: Test rflags.rf is set upon faults
Il 24/07/2014 13:55, Nadav Amit ha scritto:
> This patch tests whether rflags.rf is set upon #UD and #GP faults as it should,
> according to Intel SDM 17.3.1.1. The patch saves rflags.rf in an unused bit of
> the value which is saved during exception handling to save rflags.rf.
>
> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
> ---
> lib/x86/desc.c | 16 ++++++++++++----
> lib/x86/desc.h | 1 +
> x86/idt_test.c | 13 +++++++++----
> 3 files changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/lib/x86/desc.c b/lib/x86/desc.c
> index 9a80f48..7fbe774 100644
> --- a/lib/x86/desc.c
> +++ b/lib/x86/desc.c
> @@ -36,8 +36,8 @@ static void check_exception_table(struct ex_regs *regs)
> struct ex_record *ex;
> unsigned ex_val;
>
> - ex_val = regs->vector | (regs->error_code << 16);
> -
> + ex_val = regs->vector | (regs->error_code << 16) |
> + (((regs->rflags >> 16) & 1) << 8);
> asm("mov %0, %%gs:4" : : "r"(ex_val));
>
> for (ex = &exception_table_start; ex != &exception_table_end; ++ex) {
> @@ -173,9 +173,9 @@ void setup_idt(void)
>
> unsigned exception_vector(void)
> {
> - unsigned short vector;
> + unsigned char vector;
>
> - asm("mov %%gs:4, %0" : "=rm"(vector));
> + asm("movb %%gs:4, %0" : "=q"(vector));
> return vector;
> }
>
> @@ -187,6 +187,14 @@ unsigned exception_error_code(void)
> return error_code;
> }
>
> +bool exception_rflags_rf(void)
> +{
> + unsigned char rf_flag;
> +
> + asm("movb %%gs:5, %b0" : "=q"(rf_flag));
> + return rf_flag & 1;
> +}
> +
> static char intr_alt_stack[4096];
>
> #ifndef __x86_64__
> diff --git a/lib/x86/desc.h b/lib/x86/desc.h
> index 553bce9..bd4293e 100644
> --- a/lib/x86/desc.h
> +++ b/lib/x86/desc.h
> @@ -144,6 +144,7 @@ extern tss64_t tss;
>
> unsigned exception_vector(void);
> unsigned exception_error_code(void);
> +bool exception_rflags_rf(void);
> void set_idt_entry(int vec, void *addr, int dpl);
> void set_idt_sel(int vec, u16 sel);
> void set_gdt_entry(int sel, u32 base, u32 limit, u8 access, u8 gran);
> diff --git a/x86/idt_test.c b/x86/idt_test.c
> index ecb76bb..349aade 100644
> --- a/x86/idt_test.c
> +++ b/x86/idt_test.c
> @@ -1,15 +1,16 @@
> #include "libcflat.h"
> #include "desc.h"
>
> -int test_ud2(void)
> +int test_ud2(bool *rflags_rf)
> {
> asm volatile(ASM_TRY("1f")
> "ud2 \n\t"
> "1:" :);
> + *rflags_rf = exception_rflags_rf();
> return exception_vector();
> }
>
> -int test_gp(void)
> +int test_gp(bool *rflags_rf)
> {
> unsigned long tmp;
>
> @@ -18,19 +19,23 @@ int test_gp(void)
> "mov %0, %%cr4\n\t"
> "1:"
> : "=a"(tmp));
> + *rflags_rf = exception_rflags_rf();
> return exception_vector();
> }
>
> int main(void)
> {
> int r;
> + bool rflags_rf;
>
> printf("Starting IDT test\n");
> setup_idt();
> - r = test_gp();
> + r = test_gp(&rflags_rf);
> report("Testing #GP", r == GP_VECTOR);
> - r = test_ud2();
> + report("Testing #GP rflags.rf", rflags_rf);
> + r = test_ud2(&rflags_rf);
> report("Testing #UD", r == UD_VECTOR);
> + report("Testing #UD rflags.rf", rflags_rf);
>
> return report_summary();
> }
>

Thanks, applying to kvm-unit-tests.

Paolo


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