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SubjectRe: [RFC PATCH v2 3/3] selftests/x86: Augment SGX selftest to test new __vdso_sgx_enter_enclave() and its callback interface
On Tue, Apr 23, 2019 at 11:26:23PM -0700, Cedric Xing wrote:
> This patch augments SGX selftest with two new tests.
>
> The first test exercises the newly added callback interface, by marking the
> whole enclave range as PROT_READ, then calling mprotect() upon #PFs to add
> necessary PTE permissions per PFEC (#PF Error Code) until the enclave finishes.
> This test also serves as an example to demonstrate the callback interface.
>
> The second test single-steps through __vdso_sgx_enter_enclave() to make sure
> the call stack can be unwound at every instruction within that vDSO API. Its
> purpose is to validate the hand-crafted CFI directives in the assembly.
>
> Signed-off-by: Cedric Xing <cedric.xing@intel.com>
> ---
> tools/testing/selftests/x86/sgx/Makefile | 6 +-
> tools/testing/selftests/x86/sgx/main.c | 323 ++++++++++++++++++---
> tools/testing/selftests/x86/sgx/sgx_call.S | 40 ++-
> 3 files changed, 322 insertions(+), 47 deletions(-)
>
> diff --git a/tools/testing/selftests/x86/sgx/Makefile b/tools/testing/selftests/x86/sgx/Makefile
> index 3af15d7c8644..31f937e220c4 100644
> --- a/tools/testing/selftests/x86/sgx/Makefile
> +++ b/tools/testing/selftests/x86/sgx/Makefile
> @@ -14,16 +14,16 @@ TEST_CUSTOM_PROGS := $(OUTPUT)/test_sgx
> all_64: $(TEST_CUSTOM_PROGS)
>
> $(TEST_CUSTOM_PROGS): main.c sgx_call.S $(OUTPUT)/encl_piggy.o
> - $(CC) $(HOST_CFLAGS) -o $@ $^
> + $(CC) $(HOST_CFLAGS) -o $@ $^ -lunwind -ldl -Wl,--defsym,__image_base=0 -pie
>
> $(OUTPUT)/encl_piggy.o: encl_piggy.S $(OUTPUT)/encl.bin $(OUTPUT)/encl.ss
> $(CC) $(HOST_CFLAGS) -I$(OUTPUT) -c $< -o $@
>
> $(OUTPUT)/encl.bin: $(OUTPUT)/encl.elf
> - objcopy --remove-section=.got.plt -O binary $< $@
> + objcopy -O binary $< $@
>
> $(OUTPUT)/encl.elf: encl.lds encl.c encl_bootstrap.S
> - $(CC) $(ENCL_CFLAGS) -T $^ -o $@
> + $(CC) $(ENCL_CFLAGS) -T $^ -o $@ -Wl,--build-id=none
>
> $(OUTPUT)/encl.ss: $(OUTPUT)/sgxsign signing_key.pem $(OUTPUT)/encl.bin
> $^ $@
> diff --git a/tools/testing/selftests/x86/sgx/main.c b/tools/testing/selftests/x86/sgx/main.c
> index e2265f841fb0..d3e53c71306d 100644
> --- a/tools/testing/selftests/x86/sgx/main.c
> +++ b/tools/testing/selftests/x86/sgx/main.c
> @@ -1,6 +1,7 @@
> // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> // Copyright(c) 2016-18 Intel Corporation.
>
> +#define _GNU_SOURCE
> #include <elf.h>
> #include <fcntl.h>
> #include <stdbool.h>
> @@ -9,16 +10,31 @@
> #include <stdlib.h>
> #include <string.h>
> #include <unistd.h>
> +#include <errno.h>
> #include <sys/ioctl.h>
> #include <sys/mman.h>
> #include <sys/stat.h>
> -#include <sys/time.h>
> +#include <sys/auxv.h>
> +#include <signal.h>
> +#include <sys/ucontext.h>
> +
> +#define UNW_LOCAL_ONLY
> +#include <libunwind.h>
> +
> #include "encl_piggy.h"
> #include "defines.h"
> #include "../../../../../arch/x86/kernel/cpu/sgx/arch.h"
> #include "../../../../../arch/x86/include/uapi/asm/sgx.h"
>
> -static const uint64_t MAGIC = 0x1122334455667788ULL;
> +#define _Q(x) __Q(x)
> +#define __Q(x) #x
> +#define ERRLN "Line " _Q(__LINE__)
> +
> +#define X86_EFLAGS_TF (1ul << 8)
> +
> +extern char __image_base[];
> +size_t eenter;
> +static size_t vdso_base;
>
> struct vdso_symtab {
> Elf64_Sym *elf_symtab;
> @@ -26,20 +42,11 @@ struct vdso_symtab {
> Elf64_Word *elf_hashtab;
> };
>
> -static void *vdso_get_base_addr(char *envp[])
> +static void vdso_init(void)
> {
> - Elf64_auxv_t *auxv;
> - int i;
> -
> - for (i = 0; envp[i]; i++);
> - auxv = (Elf64_auxv_t *)&envp[i + 1];
> -
> - for (i = 0; auxv[i].a_type != AT_NULL; i++) {
> - if (auxv[i].a_type == AT_SYSINFO_EHDR)
> - return (void *)auxv[i].a_un.a_val;
> - }
> -
> - return NULL;
> + vdso_base = getauxval(AT_SYSINFO_EHDR);
> + if (!vdso_base)
> + exit(1);
> }

The clean up makes sense but should be a separate patch i.e. one
logical change per patch. Right now the patch does other mods
than the ones explcitly stated in the commit message.

I'd suggest open coding vdso_init() to the call site in that
patch.

Please try to always minimize for diff's.

>
> static Elf64_Dyn *vdso_get_dyntab(void *addr)
> @@ -66,8 +73,9 @@ static void *vdso_get_dyn(void *addr, Elf64_Dyn *dyntab, Elf64_Sxword tag)
> return NULL;
> }
>
> -static bool vdso_get_symtab(void *addr, struct vdso_symtab *symtab)
> +static bool vdso_get_symtab(struct vdso_symtab *symtab)
> {
> + void *addr = (void *)vdso_base;
> Elf64_Dyn *dyntab = vdso_get_dyntab(addr);
>
> symtab->elf_symtab = vdso_get_dyn(addr, dyntab, DT_SYMTAB);
> @@ -138,7 +146,7 @@ static bool encl_create(int dev_fd, unsigned long bin_size,
> base = mmap(NULL, secs->size, PROT_READ | PROT_WRITE | PROT_EXEC,
> MAP_SHARED, dev_fd, 0);
> if (base == MAP_FAILED) {
> - perror("mmap");
> + perror(ERRLN);
> return false;
> }
>
> @@ -224,35 +232,271 @@ static bool encl_load(struct sgx_secs *secs, unsigned long bin_size)
> return false;
> }
>
> -void sgx_call(void *rdi, void *rsi, void *tcs,
> - struct sgx_enclave_exception *exception,
> - void *eenter);
> +int sgx_call(void *rdi, void *rsi, long rdx, void *rcx, void *r8, void *r9,
> + void *tcs, struct sgx_enclave_exinfo *ei, void *cb);
> +
> +static void show_enclave_exinfo(const struct sgx_enclave_exinfo *exinfop,
> + const char *header)
> +{
> + static const char * const enclu_leaves[] = {
> + "EREPORT",
> + "EGETKEY",
> + "EENTER",
> + "ERESUME",
> + "EEXIT"
> + };
> + static const char * const exception_names[] = {
> + "#DE",
> + "#DB",
> + "NMI",
> + "#BP",
> + "#OF",
> + "#BR",
> + "#UD",
> + "#NM",
> + "#DF",
> + "CSO",
> + "#TS",
> + "#NP",
> + "#SS",
> + "#GP",
> + "#PF",
> + "Unknown",
> + "#MF",
> + "#AC",
> + "#MC",
> + "#XM",
> + "#VE",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown",
> + "Unknown"
> + };
> +
> + printf("%s: leaf:%s(%d)", header,
> + enclu_leaves[exinfop->leaf], exinfop->leaf);
> + if (exinfop->leaf != 4)
> + printf(" trap:%s(%d) ec:%d addr:0x%llx\n",
> + exception_names[exinfop->trapnr], exinfop->trapnr,
> + exinfop->error_code, exinfop->address);
> + else
> + printf("\n");
> +}
> +
> +static const uint64_t MAGIC = 0x1122334455667788ULL;
>
> -int main(int argc, char *argv[], char *envp[])
> +static void test1(struct sgx_secs *secs)

test1, test2 and test3 are not too descriptive names. Every patch should
make the code base cleaner, not messier.

/Jarkko

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