On Tue, 2023-04-04 at 16:15 +0200, Thomas Huth wrote: > On 04/04/2023 13.36, Nico Boehr wrote: > > From: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx> > > > > Test the instruction address used by targets of an execute instruction. > > When the target instruction calculates a relative address, the result is > > relative to the target instruction, not the execute instruction. > > > > Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx> > > Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx> > > Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> > > Link: https://lore.kernel.org/r/20230317112339.774659-1-nsg@xxxxxxxxxxxxx > > Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx> > > --- > > s390x/Makefile | 1 + > > s390x/ex.c | 188 ++++++++++++++++++++++++++++++++++++++++++++ > > s390x/unittests.cfg | 3 + > > .gitlab-ci.yml | 1 + > > 4 files changed, 193 insertions(+) > > create mode 100644 s390x/ex.c > > > > diff --git a/s390x/Makefile b/s390x/Makefile > > index ab146eb..a80db53 100644 > > --- a/s390x/Makefile > > +++ b/s390x/Makefile > > @@ -39,6 +39,7 @@ tests += $(TEST_DIR)/panic-loop-extint.elf > > tests += $(TEST_DIR)/panic-loop-pgm.elf > > tests += $(TEST_DIR)/migration-sck.elf > > tests += $(TEST_DIR)/exittime.elf > > +tests += $(TEST_DIR)/ex.elf > > > > pv-tests += $(TEST_DIR)/pv-diags.elf > > > > diff --git a/s390x/ex.c b/s390x/ex.c > > new file mode 100644 > > index 0000000..dbd8030 > > --- /dev/null > > +++ b/s390x/ex.c > > @@ -0,0 +1,188 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * Copyright IBM Corp. 2023 > > + * > > + * Test EXECUTE (RELATIVE LONG). > > + * These instructions execute a target instruction. The target instruction is formed > > + * by reading an instruction from memory and optionally modifying some of its bits. > > + * The execution of the target instruction is the same as if it was executed > > + * normally as part of the instruction sequence, except for the instruction > > + * address and the instruction-length code. > > + */ > > + > > +#include <libcflat.h> > > + > > +/* > > + * Accesses to the operand of execute-type instructions are instruction fetches. > > + * Minimum alignment is two, since the relative offset is specified by number of halfwords. > > + */ > > +asm ( ".pushsection .text.exrl_targets,\"x\"\n" > > +" .balign 2\n" > > +" .popsection\n" > > +); > > + > > +/* > > + * BRANCH AND SAVE, register register variant. > > + * Saves the next instruction address (address from PSW + length of instruction) > > + * to the first register. No branch is taken in this test, because 0 is > > + * specified as target. > > + * BASR does *not* perform a relative address calculation with an intermediate. > > + */ > > +static void test_basr(void) > > +{ > > + uint64_t ret_addr, after_ex; > > + > > + report_prefix_push("BASR"); > > + asm volatile ( ".pushsection .text.exrl_targets\n" > > + "0: basr %[ret_addr],0\n" > > + " .popsection\n" > > + > > + " larl %[after_ex],1f\n" > > + " exrl 0,0b\n" > > + "1:\n" > > + : [ret_addr] "=d" (ret_addr), > > + [after_ex] "=d" (after_ex) > > + ); > > + > > + report(ret_addr == after_ex, "return address after EX"); > > + report_prefix_pop(); > > +} > > + > > +/* > > + * BRANCH RELATIVE AND SAVE. > > + * According to PoP (Branch-Address Generation), the address calculated relative > > + * to the instruction address is relative to BRAS when it is the target of an > > + * execute-type instruction, not relative to the execute-type instruction. > > + */ > > +static void test_bras(void) > > +{ > > + uint64_t after_target, ret_addr, after_ex, branch_addr; > > + > > + report_prefix_push("BRAS"); > > + asm volatile ( ".pushsection .text.exrl_targets\n" > > + "0: bras %[ret_addr],1f\n" > > + " nopr %%r7\n" > > + "1: larl %[branch_addr],0\n" > > + " j 4f\n" > > + " .popsection\n" > > + > > + " larl %[after_target],1b\n" > > + " larl %[after_ex],3f\n" > > + "2: exrl 0,0b\n" > > +/* > > + * In case the address calculation is correct, we jump by the relative offset 1b-0b from 0b to 1b. > > + * In case the address calculation is relative to the exrl (i.e. a test failure), > > + * put a valid instruction at the same relative offset from the exrl, so the test continues in a > > + * controlled manner. > > + */ > > + "3: larl %[branch_addr],0\n" > > + "4:\n" > > + > > + " .if (1b - 0b) != (3b - 2b)\n" > > + " .error \"right and wrong target must have same offset\"\n" > > + " .endif\n" > > FWIW, this is failing with Clang 15 for me: > > s390x/ex.c:81:4: error: expected absolute expression > " .if (1b - 0b) != (3b - 2b)\n" > ^ > <inline asm>:12:6: note: instantiated into assembly here > .if (1b - 0b) != (3b - 2b) Seems gcc is smarter here than clang. > ^ > s390x/ex.c:82:4: error: right and wrong target must have same offset > " .error \"right and wrong target must have same > offset\"\n" > ^ > <inline asm>:13:2: note: instantiated into assembly here > .error "right and wrong target must have same offset" > ^ > 2 errors generated. > > Any easy ways to fix this? Just deleting that .if block would work, it's basically only a static assert. What do you think? Other than that I can't think of anything. > > Thomas >
