selftests/powerpc: Add a test of the switch_endian() syscall

This adds a test of the switch_endian() syscall we added in the previous
commit.

We test it by calling the endian switch syscall, and then executing some
code in the other endian to check everything went as expected. That code
checks registers we expect to be maintained are. If the endian switch
failed to happen that code sequence will be illegal and cause the test
to abort.

We then switch back to the original endian, do the same checks and
finally write a success message and exit(0).

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

6 files changed, 214 insertions, 1 deletions

diff --git a/tools/testing/selftests/powerpc/Makefile b/tools/testing/selftests/powerpc/Makefile
index 27dff8241de3..a5d5be7ec4c7 100644
--- a/tools/testing/selftests/powerpc/Makefile
+++ b/tools/testing/selftests/powerpc/Makefile
@@ -13,7 +13,7 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR
 
 export CC CFLAGS
 
-SUB_DIRS = pmu copyloops mm tm primitives stringloops vphn
+SUB_DIRS = pmu copyloops mm tm primitives stringloops vphn switch_endian
 
 endif
 
diff --git a/tools/testing/selftests/powerpc/switch_endian/.gitignore b/tools/testing/selftests/powerpc/switch_endian/.gitignore
new file mode 100644
index 000000000000..89e762eab676
--- /dev/null
+++ b/tools/testing/selftests/powerpc/switch_endian/.gitignore
@@ -0,0 +1,2 @@
+switch_endian_test
+check-reversed.S
diff --git a/tools/testing/selftests/powerpc/switch_endian/Makefile b/tools/testing/selftests/powerpc/switch_endian/Makefile
new file mode 100644
index 000000000000..081473db22b7
--- /dev/null
+++ b/tools/testing/selftests/powerpc/switch_endian/Makefile
@@ -0,0 +1,24 @@
+CC := $(CROSS_COMPILE)gcc
+PROGS := switch_endian_test
+
+ASFLAGS += -O2 -Wall -g -nostdlib -m64
+
+all: $(PROGS)
+
+switch_endian_test: check-reversed.S
+
+check-reversed.o: check.o
+        $(CROSS_COMPILE)objcopy -j .text --reverse-bytes=4 -O binary $< $@
+
+check-reversed.S: check-reversed.o
+        hexdump -v -e '/1 ".byte 0x%02X\n"' $< > $@
+
+run_tests: all
+        @-for PROG in $(PROGS); do \
+                ./$$PROG; \
+        done;
+
+clean:
+        rm -f $(PROGS) *.o check-reversed.S
+
+.PHONY: all run_tests clean
diff --git a/tools/testing/selftests/powerpc/switch_endian/check.S b/tools/testing/selftests/powerpc/switch_endian/check.S
new file mode 100644
index 000000000000..e2484d2c24f4
--- /dev/null
+++ b/tools/testing/selftests/powerpc/switch_endian/check.S
@@ -0,0 +1,100 @@
+#include "common.h"
+
+/*
+ * Checks that registers contain what we expect, ie. they were not clobbered by
+ * the syscall.
+ *
+ * r15: pattern to check registers against.
+ *
+ * At the end r3 == 0 if everything's OK.
+ */
+        nop                     # guaranteed to be illegal in reverse-endian
+        mr      r9,r15
+        cmpd    r9,r3           # check r3
+        bne     1f
+        addi    r9,r15,4        # check r4
+        cmpd    r9,r4
+        bne     1f
+        lis     r9,0x00FF       # check CR
+        ori     r9,r9,0xF000
+        mfcr    r10
+        and     r10,r10,r9
+        cmpw    r9,r10
+        addi    r9,r15,34
+        bne     1f
+        addi    r9,r15,32       # check LR
+        mflr    r10
+        cmpd    r9,r10
+        bne     1f
+        addi    r9,r15,5        # check r5
+        cmpd    r9,r5
+        bne     1f
+        addi    r9,r15,6        # check r6
+        cmpd    r9,r6
+        bne     1f
+        addi    r9,r15,7        # check r7
+        cmpd    r9,r7
+        bne     1f
+        addi    r9,r15,8        # check r8
+        cmpd    r9,r8
+        bne     1f
+        addi    r9,r15,13       # check r13
+        cmpd    r9,r13
+        bne     1f
+        addi    r9,r15,14       # check r14
+        cmpd    r9,r14
+        bne     1f
+        addi    r9,r15,16       # check r16
+        cmpd    r9,r16
+        bne     1f
+        addi    r9,r15,17       # check r17
+        cmpd    r9,r17
+        bne     1f
+        addi    r9,r15,18       # check r18
+        cmpd    r9,r18
+        bne     1f
+        addi    r9,r15,19       # check r19
+        cmpd    r9,r19
+        bne     1f
+        addi    r9,r15,20       # check r20
+        cmpd    r9,r20
+        bne     1f
+        addi    r9,r15,21       # check r21
+        cmpd    r9,r21
+        bne     1f
+        addi    r9,r15,22       # check r22
+        cmpd    r9,r22
+        bne     1f
+        addi    r9,r15,23       # check r23
+        cmpd    r9,r23
+        bne     1f
+        addi    r9,r15,24       # check r24
+        cmpd    r9,r24
+        bne     1f
+        addi    r9,r15,25       # check r25
+        cmpd    r9,r25
+        bne     1f
+        addi    r9,r15,26       # check r26
+        cmpd    r9,r26
+        bne     1f
+        addi    r9,r15,27       # check r27
+        cmpd    r9,r27
+        bne     1f
+        addi    r9,r15,28       # check r28
+        cmpd    r9,r28
+        bne     1f
+        addi    r9,r15,29       # check r29
+        cmpd    r9,r29
+        bne     1f
+        addi    r9,r15,30       # check r30
+        cmpd    r9,r30
+        bne     1f
+        addi    r9,r15,31       # check r31
+        cmpd    r9,r31
+        bne     1f
+        b       2f
+1:      mr      r3, r9
+        li      r0, __NR_exit
+        sc
+2:      li      r0, __NR_switch_endian
+        nop
diff --git a/tools/testing/selftests/powerpc/switch_endian/common.h b/tools/testing/selftests/powerpc/switch_endian/common.h
new file mode 100644
index 000000000000..69e399698c64
--- /dev/null
+++ b/tools/testing/selftests/powerpc/switch_endian/common.h
@@ -0,0 +1,6 @@
+#include <ppc-asm.h>
+#include <asm/unistd.h>
+
+#ifndef __NR_switch_endian
+#define __NR_switch_endian 363
+#endif
diff --git a/tools/testing/selftests/powerpc/switch_endian/switch_endian_test.S b/tools/testing/selftests/powerpc/switch_endian/switch_endian_test.S
new file mode 100644
index 000000000000..ef7c971abb67
--- /dev/null
+++ b/tools/testing/selftests/powerpc/switch_endian/switch_endian_test.S
@@ -0,0 +1,81 @@
+#include "common.h"
+
+        .data
+        .balign 8
+message:
+        .ascii "success: switch_endian_test\n\0"
+
+        .section ".toc"
+        .balign 8
+pattern:
+        .llong 0x5555AAAA5555AAAA
+
+        .text
+FUNC_START(_start)
+        /* Load the pattern */
+        ld      r15, pattern@TOC(%r2)
+
+        /* Setup CR, only CR2-CR4 are maintained */
+        lis     r3, 0x00FF
+        ori     r3, r3, 0xF000
+        mtcr    r3
+
+        /* Load the pattern slightly modified into the registers */
+        mr      r3, r15
+        addi    r4, r15, 4
+
+        addi    r5, r15, 32
+        mtlr    r5
+
+        addi    r5, r15, 5
+        addi    r6, r15, 6
+        addi    r7, r15, 7
+        addi    r8, r15, 8
+
+        /* r9 - r12 are clobbered */
+
+        addi    r13, r15, 13
+        addi    r14, r15, 14
+
+        /* Skip r15 we're using it */
+
+        addi    r16, r15, 16
+        addi    r17, r15, 17
+        addi    r18, r15, 18
+        addi    r19, r15, 19
+        addi    r20, r15, 20
+        addi    r21, r15, 21
+        addi    r22, r15, 22
+        addi    r23, r15, 23
+        addi    r24, r15, 24
+        addi    r25, r15, 25
+        addi    r26, r15, 26
+        addi    r27, r15, 27
+        addi    r28, r15, 28
+        addi    r29, r15, 29
+        addi    r30, r15, 30
+        addi    r31, r15, 31
+
+        /*
+         * Call the syscall to switch endian.
+         * It clobbers r9-r12, XER, CTR and CR0-1,5-7.
+         */
+        li r0, __NR_switch_endian
+        sc
+
+#include "check-reversed.S"
+
+        /* Flip back, r0 already has the switch syscall number */
+        .long   0x02000044      /* sc */
+
+#include "check.S"
+
+        li      r0, __NR_write
+        li      r3, 1   /* stdout */
+        ld      r4, message@got(%r2)
+        li      r5, 28  /* strlen(message3) */
+        sc
+        li      r0, __NR_exit
+        li      r3, 0
+        sc
+        b       .