| Message ID | 1408304076-2862-1-git-send-email-namit@cs.technion.ac.il (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Il 17/08/2014 21:34, Nadav Amit ha scritto: > Commit 5045b46803 added a check that cs.dpl equals cs.rpl during task-switch. > This is a wrong check, and this test introduces a test in which cs.dpl != > cs.rpl. To do so, it configures tss.cs to be conforming with rpl=3 and dpl=0. > Since the cpl after calling is 3, it does not make any prints in the callee. > > Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> > --- > x86/taskswitch2.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/x86/taskswitch2.c b/x86/taskswitch2.c > index 92fc941..d96853f 100644 > --- a/x86/taskswitch2.c > +++ b/x86/taskswitch2.c > @@ -7,6 +7,8 @@ > > #define MAIN_TSS_SEL (FIRST_SPARE_SEL + 0) > #define VM86_TSS_SEL (FIRST_SPARE_SEL + 8) > +#define USER_CS_SEL (FIRST_SPARE_SEL + 16) Please call it CONFORM_CS_SEL since it's not really a user-mode selector (DPL=0), it's just used as one (RPL=3). > +#define USER_DS_SEL (FIRST_SPARE_SEL + 24) Not needed, see below. > > static volatile int test_count; > static volatile unsigned int test_divider; > @@ -102,6 +104,14 @@ start: > goto start; > } > > +static void user_tss(void) > +{ > +start: Please add a printf and print_current_tss_info() here. > + test_count++; > + asm volatile ("iret"); > + goto start; > +} > + > void test_kernel_mode_int() > { > unsigned int res; > @@ -201,6 +211,18 @@ void test_kernel_mode_int() > asm volatile ("ljmp $" xstr(TSS_INTR) ", $0xf4f4f4f4"); > printf("Jump back succeeded\n"); > report("ljmp", test_count == 1); > + > + /* test lcall with conforming segment, cs.dpl != cs.rpl */ > + test_count = 0; > + set_intr_task_gate(0, user_tss); > + > + tss_intr.cs = USER_CS_SEL | 3; > + tss_intr.ss = USER_DS_SEL | 3; > + tss_intr.ds = tss_intr.gs = tss_intr.fs = tss_intr.ss; > + set_gdt_entry(USER_CS_SEL, 0, 0xffffffff, 0x9f, 0xc0); > + set_gdt_entry(USER_DS_SEL, 0, 0xffffffff, 0xf3, 0xc0); You can use USER_DS here. Also, please put the test in a separate function and call it last (after test_vm86_switch), because a failure in this test breaks test_vm86_switch too. Paolo > + asm volatile("lcall $" xstr(TSS_INTR) ", $0xf4f4f4f4"); > + report("lcall when cs.rpl != cs.dpl", test_count == 1); > } > > void test_vm86_switch(void) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/x86/taskswitch2.c b/x86/taskswitch2.c index 92fc941..d96853f 100644 --- a/x86/taskswitch2.c +++ b/x86/taskswitch2.c @@ -7,6 +7,8 @@ #define MAIN_TSS_SEL (FIRST_SPARE_SEL + 0) #define VM86_TSS_SEL (FIRST_SPARE_SEL + 8) +#define USER_CS_SEL (FIRST_SPARE_SEL + 16) +#define USER_DS_SEL (FIRST_SPARE_SEL + 24) static volatile int test_count; static volatile unsigned int test_divider; @@ -102,6 +104,14 @@ start: goto start; } +static void user_tss(void) +{ +start: + test_count++; + asm volatile ("iret"); + goto start; +} + void test_kernel_mode_int() { unsigned int res; @@ -201,6 +211,18 @@ void test_kernel_mode_int() asm volatile ("ljmp $" xstr(TSS_INTR) ", $0xf4f4f4f4"); printf("Jump back succeeded\n"); report("ljmp", test_count == 1); + + /* test lcall with conforming segment, cs.dpl != cs.rpl */ + test_count = 0; + set_intr_task_gate(0, user_tss); + + tss_intr.cs = USER_CS_SEL | 3; + tss_intr.ss = USER_DS_SEL | 3; + tss_intr.ds = tss_intr.gs = tss_intr.fs = tss_intr.ss; + set_gdt_entry(USER_CS_SEL, 0, 0xffffffff, 0x9f, 0xc0); + set_gdt_entry(USER_DS_SEL, 0, 0xffffffff, 0xf3, 0xc0); + asm volatile("lcall $" xstr(TSS_INTR) ", $0xf4f4f4f4"); + report("lcall when cs.rpl != cs.dpl", test_count == 1); } void test_vm86_switch(void)
Commit 5045b46803 added a check that cs.dpl equals cs.rpl during task-switch. This is a wrong check, and this test introduces a test in which cs.dpl != cs.rpl. To do so, it configures tss.cs to be conforming with rpl=3 and dpl=0. Since the cpl after calling is 3, it does not make any prints in the callee. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> --- x86/taskswitch2.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)