Message ID | 1606206780-80123-1-git-send-email-bmeng.cn@gmail.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | [kvm-unit-tests,RFC] x86: Add a new test case for ret/iret with a nullified segment | expand |
On 24/11/20 09:33, Bin Meng wrote: > From: Bin Meng <bin.meng@windriver.com> > > This makes up the test case for the following QEMU patch: > http://patchwork.ozlabs.org/project/qemu-devel/patch/1605261378-77971-1-git-send-email-bmeng.cn@gmail.com/ > > Note the test case only fails on an unpatched QEMU with "accel=tcg". > > Signed-off-by: Bin Meng <bin.meng@windriver.com> > --- > Sending this as RFC since I am new to kvm-unit-tests > > x86/emulator.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/x86/emulator.c b/x86/emulator.c > index e46d97e..6100b6d 100644 > --- a/x86/emulator.c > +++ b/x86/emulator.c > @@ -6,10 +6,14 @@ > #include "processor.h" > #include "vmalloc.h" > #include "alloc_page.h" > +#include "usermode.h" > > #define memset __builtin_memset > #define TESTDEV_IO_PORT 0xe0 > > +#define MAGIC_NUM 0xdeadbeefdeadbeefUL > +#define GS_BASE 0x400000 > + > static int exceptions; > > /* Forced emulation prefix, used to invoke the emulator unconditionally. */ > @@ -925,6 +929,39 @@ static void test_sreg(volatile uint16_t *mem) > write_ss(ss); > } > > +static uint64_t usr_gs_mov(void) > +{ > + static uint64_t dummy = MAGIC_NUM; > + uint64_t dummy_ptr = (uint64_t)&dummy; > + uint64_t ret; > + > + dummy_ptr -= GS_BASE; > + asm volatile("mov %%gs:(%%rcx), %%rax" : "=a"(ret): "c"(dummy_ptr) :); > + > + return ret; > +} > + > +static void test_iret(void) > +{ > + uint64_t val; > + bool raised_vector; > + > + /* Update GS base to 4MiB */ > + wrmsr(MSR_GS_BASE, GS_BASE); > + > + /* > + * Per the SDM, jumping to user mode via `iret`, which is returning to > + * outer privilege level, for segment registers (ES, FS, GS, and DS) > + * if the check fails, the segment selector becomes null. > + * > + * In our test case, GS becomes null. > + */ > + val = run_in_user((usermode_func)usr_gs_mov, GP_VECTOR, > + 0, 0, 0, 0, &raised_vector); > + > + report(val == MAGIC_NUM, "Test ret/iret with a nullified segment"); > +} > + > /* Broken emulation causes triple fault, which skips the other tests. */ > #if 0 > static void test_lldt(volatile uint16_t *mem) > @@ -1074,6 +1111,7 @@ int main(void) > test_shld_shrd(mem); > //test_lgdt_lidt(mem); > test_sreg(mem); > + test_iret(); > //test_lldt(mem); > test_ltr(mem); > test_cmov(mem); > Thanks, the patch is good. Paolo
Hi Paolo, On Tue, Nov 24, 2020 at 5:12 PM Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 24/11/20 09:33, Bin Meng wrote: > > From: Bin Meng <bin.meng@windriver.com> > > > > This makes up the test case for the following QEMU patch: > > http://patchwork.ozlabs.org/project/qemu-devel/patch/1605261378-77971-1-git-send-email-bmeng.cn@gmail.com/ > > > > Note the test case only fails on an unpatched QEMU with "accel=tcg". > > > > Signed-off-by: Bin Meng <bin.meng@windriver.com> > > --- > > Sending this as RFC since I am new to kvm-unit-tests > > > > x86/emulator.c | 38 ++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 38 insertions(+) > > > > diff --git a/x86/emulator.c b/x86/emulator.c > > index e46d97e..6100b6d 100644 > > --- a/x86/emulator.c > > +++ b/x86/emulator.c > > @@ -6,10 +6,14 @@ > > #include "processor.h" > > #include "vmalloc.h" > > #include "alloc_page.h" > > +#include "usermode.h" > > > > #define memset __builtin_memset > > #define TESTDEV_IO_PORT 0xe0 > > > > +#define MAGIC_NUM 0xdeadbeefdeadbeefUL > > +#define GS_BASE 0x400000 > > + > > static int exceptions; > > > > /* Forced emulation prefix, used to invoke the emulator unconditionally. */ > > @@ -925,6 +929,39 @@ static void test_sreg(volatile uint16_t *mem) > > write_ss(ss); > > } > > > > +static uint64_t usr_gs_mov(void) > > +{ > > + static uint64_t dummy = MAGIC_NUM; > > + uint64_t dummy_ptr = (uint64_t)&dummy; > > + uint64_t ret; > > + > > + dummy_ptr -= GS_BASE; > > + asm volatile("mov %%gs:(%%rcx), %%rax" : "=a"(ret): "c"(dummy_ptr) :); > > + > > + return ret; > > +} > > + > > +static void test_iret(void) > > +{ > > + uint64_t val; > > + bool raised_vector; > > + > > + /* Update GS base to 4MiB */ > > + wrmsr(MSR_GS_BASE, GS_BASE); > > + > > + /* > > + * Per the SDM, jumping to user mode via `iret`, which is returning to > > + * outer privilege level, for segment registers (ES, FS, GS, and DS) > > + * if the check fails, the segment selector becomes null. > > + * > > + * In our test case, GS becomes null. > > + */ > > + val = run_in_user((usermode_func)usr_gs_mov, GP_VECTOR, > > + 0, 0, 0, 0, &raised_vector); > > + > > + report(val == MAGIC_NUM, "Test ret/iret with a nullified segment"); > > +} > > + > > /* Broken emulation causes triple fault, which skips the other tests. */ > > #if 0 > > static void test_lldt(volatile uint16_t *mem) > > @@ -1074,6 +1111,7 @@ int main(void) > > test_shld_shrd(mem); > > //test_lgdt_lidt(mem); > > test_sreg(mem); > > + test_iret(); > > //test_lldt(mem); > > test_ltr(mem); > > test_cmov(mem); > > > > Thanks, the patch is good. Is this patch applied? Regards, Bin
On 16/01/21 15:16, Bin Meng wrote: > Hi Paolo, > > On Tue, Nov 24, 2020 at 5:12 PM Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> On 24/11/20 09:33, Bin Meng wrote: >>> From: Bin Meng <bin.meng@windriver.com> >>> >>> This makes up the test case for the following QEMU patch: >>> http://patchwork.ozlabs.org/project/qemu-devel/patch/1605261378-77971-1-git-send-email-bmeng.cn@gmail.com/ >>> >>> Note the test case only fails on an unpatched QEMU with "accel=tcg". >>> >>> Signed-off-by: Bin Meng <bin.meng@windriver.com> >>> --- >>> Sending this as RFC since I am new to kvm-unit-tests >>> >>> x86/emulator.c | 38 ++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 38 insertions(+) >>> >>> diff --git a/x86/emulator.c b/x86/emulator.c >>> index e46d97e..6100b6d 100644 >>> --- a/x86/emulator.c >>> +++ b/x86/emulator.c >>> @@ -6,10 +6,14 @@ >>> #include "processor.h" >>> #include "vmalloc.h" >>> #include "alloc_page.h" >>> +#include "usermode.h" >>> >>> #define memset __builtin_memset >>> #define TESTDEV_IO_PORT 0xe0 >>> >>> +#define MAGIC_NUM 0xdeadbeefdeadbeefUL >>> +#define GS_BASE 0x400000 >>> + >>> static int exceptions; >>> >>> /* Forced emulation prefix, used to invoke the emulator unconditionally. */ >>> @@ -925,6 +929,39 @@ static void test_sreg(volatile uint16_t *mem) >>> write_ss(ss); >>> } >>> >>> +static uint64_t usr_gs_mov(void) >>> +{ >>> + static uint64_t dummy = MAGIC_NUM; >>> + uint64_t dummy_ptr = (uint64_t)&dummy; >>> + uint64_t ret; >>> + >>> + dummy_ptr -= GS_BASE; >>> + asm volatile("mov %%gs:(%%rcx), %%rax" : "=a"(ret): "c"(dummy_ptr) :); >>> + >>> + return ret; >>> +} >>> + >>> +static void test_iret(void) >>> +{ >>> + uint64_t val; >>> + bool raised_vector; >>> + >>> + /* Update GS base to 4MiB */ >>> + wrmsr(MSR_GS_BASE, GS_BASE); >>> + >>> + /* >>> + * Per the SDM, jumping to user mode via `iret`, which is returning to >>> + * outer privilege level, for segment registers (ES, FS, GS, and DS) >>> + * if the check fails, the segment selector becomes null. >>> + * >>> + * In our test case, GS becomes null. >>> + */ >>> + val = run_in_user((usermode_func)usr_gs_mov, GP_VECTOR, >>> + 0, 0, 0, 0, &raised_vector); >>> + >>> + report(val == MAGIC_NUM, "Test ret/iret with a nullified segment"); >>> +} >>> + >>> /* Broken emulation causes triple fault, which skips the other tests. */ >>> #if 0 >>> static void test_lldt(volatile uint16_t *mem) >>> @@ -1074,6 +1111,7 @@ int main(void) >>> test_shld_shrd(mem); >>> //test_lgdt_lidt(mem); >>> test_sreg(mem); >>> + test_iret(); >>> //test_lldt(mem); >>> test_ltr(mem); >>> test_cmov(mem); >>> >> >> Thanks, the patch is good. > > Is this patch applied? > > Regards, > Bin > Yes, it is. Paolo
diff --git a/x86/emulator.c b/x86/emulator.c index e46d97e..6100b6d 100644 --- a/x86/emulator.c +++ b/x86/emulator.c @@ -6,10 +6,14 @@ #include "processor.h" #include "vmalloc.h" #include "alloc_page.h" +#include "usermode.h" #define memset __builtin_memset #define TESTDEV_IO_PORT 0xe0 +#define MAGIC_NUM 0xdeadbeefdeadbeefUL +#define GS_BASE 0x400000 + static int exceptions; /* Forced emulation prefix, used to invoke the emulator unconditionally. */ @@ -925,6 +929,39 @@ static void test_sreg(volatile uint16_t *mem) write_ss(ss); } +static uint64_t usr_gs_mov(void) +{ + static uint64_t dummy = MAGIC_NUM; + uint64_t dummy_ptr = (uint64_t)&dummy; + uint64_t ret; + + dummy_ptr -= GS_BASE; + asm volatile("mov %%gs:(%%rcx), %%rax" : "=a"(ret): "c"(dummy_ptr) :); + + return ret; +} + +static void test_iret(void) +{ + uint64_t val; + bool raised_vector; + + /* Update GS base to 4MiB */ + wrmsr(MSR_GS_BASE, GS_BASE); + + /* + * Per the SDM, jumping to user mode via `iret`, which is returning to + * outer privilege level, for segment registers (ES, FS, GS, and DS) + * if the check fails, the segment selector becomes null. + * + * In our test case, GS becomes null. + */ + val = run_in_user((usermode_func)usr_gs_mov, GP_VECTOR, + 0, 0, 0, 0, &raised_vector); + + report(val == MAGIC_NUM, "Test ret/iret with a nullified segment"); +} + /* Broken emulation causes triple fault, which skips the other tests. */ #if 0 static void test_lldt(volatile uint16_t *mem) @@ -1074,6 +1111,7 @@ int main(void) test_shld_shrd(mem); //test_lgdt_lidt(mem); test_sreg(mem); + test_iret(); //test_lldt(mem); test_ltr(mem); test_cmov(mem);