selftests/powerpc: Ensure 16-byte stack pointer alignment

The PUSH/POP_BASIC_STACK helpers in basic_asm.h do not ensure that the
stack pointer is always 16-byte aligned, which is required per the ABI.

Fix the macros to do the alignment if the caller fails to.

Currently only one caller passes a non-aligned size, tm_signal_self(),
which hasn't been caught in testing, presumably because it's a leaf
function.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220627140239.2464900-1-mpe@ellerman.id.au

diff --git a/tools/testing/selftests/powerpc/include/basic_asm.h b/tools/testing/selftests/powerpc/include/basic_asm.h
index 886dc02..807e83e 100644 (file)
--- a/tools/testing/selftests/powerpc/include/basic_asm.h
+++ b/tools/testing/selftests/powerpc/include/basic_asm.h
@@ -58,7 +58,7 @@
 #define PUSH_BASIC_STACK(_extra) \
        mflr    r0; \
        std     r0, STACK_FRAME_LR_POS(%r1); \
-       stdu    %r1, -(_extra + STACK_FRAME_MIN_SIZE)(%r1); \
+       stdu    %r1, -(((_extra + 15) & ~15) + STACK_FRAME_MIN_SIZE)(%r1); \
        mfcr    r0; \
        stw     r0, STACK_FRAME_CR_POS(%r1); \
        std     %r2, STACK_FRAME_TOC_POS(%r1);
@@ -67,7 +67,7 @@
        ld      %r2, STACK_FRAME_TOC_POS(%r1); \
        lwz     r0, STACK_FRAME_CR_POS(%r1); \
        mtcr    r0; \
-       addi    %r1, %r1, (_extra + STACK_FRAME_MIN_SIZE); \
+       addi    %r1, %r1, (((_extra + 15) & ~15) + STACK_FRAME_MIN_SIZE); \
        ld      r0, STACK_FRAME_LR_POS(%r1); \
        mtlr    r0;