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SubjectRe: [PATCH v6 8/8] powerpc/watchpoint/selftests: Tests for kernel accessing user memory
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On 9/2/20 1:29 AM, Ravi Bangoria wrote:
> Introduce tests to cover simple scenarios where user is watching
> memory which can be accessed by kernel as well. We also support
> _MODE_EXACT with _SETHWDEBUG interface. Move those testcases out-
> side of _BP_RANGE condition. This will help to test _MODE_EXACT
> scenarios when CONFIG_HAVE_HW_BREAKPOINT is not set, eg:
>
> $ ./ptrace-hwbreak
> ...
> PTRACE_SET_DEBUGREG, Kernel Access Userspace, len: 8: Ok
> PPC_PTRACE_SETHWDEBUG, MODE_EXACT, WO, len: 1: Ok
> PPC_PTRACE_SETHWDEBUG, MODE_EXACT, RO, len: 1: Ok
> PPC_PTRACE_SETHWDEBUG, MODE_EXACT, RW, len: 1: Ok
> PPC_PTRACE_SETHWDEBUG, MODE_EXACT, Kernel Access Userspace, len: 1: Ok
> success: ptrace-hwbreak
>
> Suggested-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Rogerio Alves <rcardoso@linux.ibm.com>
> ---
> .../selftests/powerpc/ptrace/ptrace-hwbreak.c | 48 ++++++++++++++++++-
> 1 file changed, 46 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
> index fc477dfe86a2..2e0d86e0687e 100644
> --- a/tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
> +++ b/tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
> @@ -20,6 +20,8 @@
> #include <signal.h>
> #include <sys/types.h>
> #include <sys/wait.h>
> +#include <sys/syscall.h>
> +#include <linux/limits.h>
> #include "ptrace.h"
>
> #define SPRN_PVR 0x11F
> @@ -44,6 +46,7 @@ struct gstruct {
> };
> static volatile struct gstruct gstruct __attribute__((aligned(512)));
>
> +static volatile char cwd[PATH_MAX] __attribute__((aligned(8)));
>
> static void get_dbginfo(pid_t child_pid, struct ppc_debug_info *dbginfo)
> {
> @@ -138,6 +141,9 @@ static void test_workload(void)
> write_var(len);
> }
>
> + /* PTRACE_SET_DEBUGREG, Kernel Access Userspace test */
> + syscall(__NR_getcwd, &cwd, PATH_MAX);
> +
> /* PPC_PTRACE_SETHWDEBUG, MODE_EXACT, WO test */
> write_var(1);
>
> @@ -150,6 +156,9 @@ static void test_workload(void)
> else
> read_var(1);
>
> + /* PPC_PTRACE_SETHWDEBUG, MODE_EXACT, Kernel Access Userspace test */
> + syscall(__NR_getcwd, &cwd, PATH_MAX);
> +
> /* PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW ALIGNED, WO test */
> gstruct.a[rand() % A_LEN] = 'a';
>
> @@ -293,6 +302,24 @@ static int test_set_debugreg(pid_t child_pid)
> return 0;
> }
>
> +static int test_set_debugreg_kernel_userspace(pid_t child_pid)
> +{
> + unsigned long wp_addr = (unsigned long)cwd;
> + char *name = "PTRACE_SET_DEBUGREG";
> +
> + /* PTRACE_SET_DEBUGREG, Kernel Access Userspace test */
> + wp_addr &= ~0x7UL;
> + wp_addr |= (1Ul << DABR_READ_SHIFT);
> + wp_addr |= (1UL << DABR_WRITE_SHIFT);
> + wp_addr |= (1UL << DABR_TRANSLATION_SHIFT);
> + ptrace_set_debugreg(child_pid, wp_addr);
> + ptrace(PTRACE_CONT, child_pid, NULL, 0);
> + check_success(child_pid, name, "Kernel Access Userspace", wp_addr, 8);
> +
> + ptrace_set_debugreg(child_pid, 0);
> + return 0;
> +}
> +
> static void get_ppc_hw_breakpoint(struct ppc_hw_breakpoint *info, int type,
> unsigned long addr, int len)
> {
> @@ -338,6 +365,22 @@ static void test_sethwdebug_exact(pid_t child_pid)
> ptrace_delhwdebug(child_pid, wh);
> }
>
> +static void test_sethwdebug_exact_kernel_userspace(pid_t child_pid)
> +{
> + struct ppc_hw_breakpoint info;
> + unsigned long wp_addr = (unsigned long)&cwd;
> + char *name = "PPC_PTRACE_SETHWDEBUG, MODE_EXACT";
> + int len = 1; /* hardcoded in kernel */
> + int wh;
> +
> + /* PPC_PTRACE_SETHWDEBUG, MODE_EXACT, Kernel Access Userspace test */
> + get_ppc_hw_breakpoint(&info, PPC_BREAKPOINT_TRIGGER_WRITE, wp_addr, 0);
> + wh = ptrace_sethwdebug(child_pid, &info);
> + ptrace(PTRACE_CONT, child_pid, NULL, 0);
> + check_success(child_pid, name, "Kernel Access Userspace", wp_addr, len);
> + ptrace_delhwdebug(child_pid, wh);
> +}
> +
> static void test_sethwdebug_range_aligned(pid_t child_pid)
> {
> struct ppc_hw_breakpoint info;
> @@ -452,9 +495,10 @@ static void
> run_tests(pid_t child_pid, struct ppc_debug_info *dbginfo, bool dawr)
> {
> test_set_debugreg(child_pid);
> + test_set_debugreg_kernel_userspace(child_pid);
> + test_sethwdebug_exact(child_pid);
> + test_sethwdebug_exact_kernel_userspace(child_pid);
> if (dbginfo->features & PPC_DEBUG_FEATURE_DATA_BP_RANGE) {
> - test_sethwdebug_exact(child_pid);
> -
> test_sethwdebug_range_aligned(child_pid);
> if (dawr || is_8xx) {
> test_sethwdebug_range_unaligned(child_pid);
>

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