Reviewed-by: Vasileios Almpanis <[email protected]>
On 3/24/26 1:14 PM, Konstantin Khorenko wrote:
breakpoint_test.c: In function 'read_var': breakpoint_test.c:186:33: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] 186 | sval = *(short *)&dummy_var[i]; | ^~~~~~~~~~~~~~~~~~~~~~ breakpoint_test.c:189:33: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] 189 | ival = *(int *)&dummy_var[i]; | ^~~~~~~~~~~~~~~~~~~~ breakpoint_test.c:177:52: warning: variable 'lval' set but not used [-Wunused-but-set-variable] breakpoint_test.c:177:36: warning: variable 'ival' set but not used [-Wunused-but-set-variable] breakpoint_test.c:177:26: warning: variable 'sval' set but not used [-Wunused-but-set-variable] breakpoint_test.c:177:14: warning: variable 'cval' set but not used [-Wunused-but-set-variable] breakpoint_test.c: In function 'trigger_tests': breakpoint_test.c:206:14: warning: unused variable 'val' [-Wunused-variable] breakpoint_test.c: In function 'launch_tests': breakpoint_test.c:335:33: warning: unused variable 'i' [-Wunused-variable] breakpoint_test.c: In function 'main': breakpoint_test.c:390:13: warning: unused variable 'ret' [-Wunused-variable] breakpoint_test.c: In function 'toggle_breakpoint': breakpoint_test.c:91:22: warning: 'xlen' may be used uninitialized [-Wmaybe-uninitialized] 91 | vdr7 = (xlen | xtype) << 16; | ~~~~~~^~~~~~~~ Fix the following warnings: - [-Wstrict-aliasing] in read_var(): suppress with a GCC diagnostic pragma -- the type-punned reads are intentional here: we need sized memory accesses at specific addresses to trigger hardware breakpoints. - [-Wunused-but-set-variable] in read_var(): instead of suppressing the warning with a pragma, remove the unnecessary local variables (cval, sval, ival, lval) entirely and use volatile casts on the pointer dereferences. This is the correct fix because: 1. The purpose of these reads is to trigger hardware watchpoints via memory access at specific addresses, not to use the values. 2. With -O2 the compiler is free to eliminate a dead store to a non-volatile local, so it can remove the read altogether, which would silently break the test. 3. Casting the pointer to volatile forces the compiler to emit the load instruction regardless of optimization level, which is exactly the semantics we need. - [-Wmaybe-uninitialized]: initialize xlen in toggle_breakpoint(). - [-Wunused-variable]: remove unused variables val, i, ret. https://virtuozzo.atlassian.net/browse/VSTOR-127529 Signed-off-by: Konstantin Khorenko <[email protected]> Feature: fix selftests --- v2: dropped "unused" pragma and removed unused variables instead. The second pragma to stay here. --- .../selftests/breakpoints/breakpoint_test.c | 24 ++++++++++++------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/breakpoints/breakpoint_test.c b/tools/testing/selftests/breakpoints/breakpoint_test.c index d46962a24724..6a45fde12c0b 100644 --- a/tools/testing/selftests/breakpoints/breakpoint_test.c +++ b/tools/testing/selftests/breakpoints/breakpoint_test.c @@ -55,7 +55,7 @@ static void toggle_breakpoint(int n, int type, int len, { int ret;- int xtype, xlen;+ int xtype, xlen = 0; unsigned long vdr7, dr7;switch (type) {@@ -172,29 +172,37 @@ static void write_var(int len) } }+/*+ * Type-punned reads are intentional here: we need sized memory accesses + * at specific addresses to trigger hardware breakpoints. Alternatives + * like memcpy() do not guarantee a single load of the required width, + * so we suppress the strict-aliasing warning with a pragma instead. + */ +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wstrict-aliasing" static void read_var(int len) { - char cval; short sval; int ival; long long lval; int i;for (i = 0; i < 4; i++) {switch (len) { case 1: - cval = *(char *)&dummy_var[i]; + *(volatile char *)&dummy_var[i]; break; case 2: - sval = *(short *)&dummy_var[i]; + *(volatile short *)&dummy_var[i]; break; case 4: - ival = *(int *)&dummy_var[i]; + *(volatile int *)&dummy_var[i]; break; case 8: - lval = *(long long *)&dummy_var[i]; + *(volatile long long *)&dummy_var[i]; break; } check_trapped(); } } +#pragma GCC diagnostic pop/** Do the r/w/x accesses to trigger the breakpoints. And run @@ -203,7 +211,6 @@ static void read_var(int len) static void trigger_tests(void) { int len, local, global, i; - char val; int ret;ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);@@ -332,7 +339,7 @@ static void launch_tests(void) { char buf[1024]; unsigned int tests = 0; - int len, local, global, i; + int len, local, global;tests += 3 * COUNT_ISN_BPS;tests += sizeof(long) / 2 * 3 * COUNT_WPS; @@ -387,7 +394,6 @@ static void launch_tests(void) int main(int argc, char **argv) { pid_t pid; - int ret;ksft_print_header();
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