@@ -17,6 +17,13 @@ sysdep-dl-routines += tlsdesc dl-tlsdesc
gen-as-const-headers += dl-link.sym
tests-internal += tst-ifunc-arg-1 tst-ifunc-arg-2
+
+ifeq (yes,$(aarch64-variant-pcs))
+tests += tst-vpcs
+modules-names += tst-vpcs-mod
+LDFLAGS-tst-vpcs-mod.so = -Wl,-z,lazy
+$(objpfx)tst-vpcs: $(objpfx)tst-vpcs-mod.so
+endif
endif
ifeq ($(subdir),csu)
@@ -255,3 +255,43 @@ if test $libc_cv_aarch64_pac_ret = yes; then
$as_echo "#define HAVE_AARCH64_PAC_RET 1" >>confdefs.h
fi
+
+# Check if binutils supports variant PCS symbols.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for variant PCS support" >&5
+$as_echo_n "checking for variant PCS support... " >&6; }
+if ${libc_cv_aarch64_variant_pcs+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ cat > conftest.S <<EOF
+.global foo
+.type foo, %function
+.variant_pcs foo
+foo:
+ ret
+.global bar
+.type bar, %function
+bar:
+ b foo
+EOF
+ libc_cv_aarch64_variant_pcs=no
+ if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles $no_ssp -shared -fPIC -o conftest.so conftest.S'
+ { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; } \
+ && { ac_try='$READELF -dW conftest.so | grep -q AARCH64_VARIANT_PCS'
+ { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; }
+ then
+ libc_cv_aarch64_variant_pcs=yes
+ fi
+ rm -rf conftest.*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_aarch64_variant_pcs" >&5
+$as_echo "$libc_cv_aarch64_variant_pcs" >&6; }
+config_vars="$config_vars
+aarch64-variant-pcs = $libc_cv_aarch64_variant_pcs"
@@ -61,3 +61,25 @@ EOF
if test $libc_cv_aarch64_pac_ret = yes; then
AC_DEFINE(HAVE_AARCH64_PAC_RET)
fi
+
+# Check if binutils supports variant PCS symbols.
+AC_CACHE_CHECK([for variant PCS support], [libc_cv_aarch64_variant_pcs], [dnl
+ cat > conftest.S <<EOF
+.global foo
+.type foo, %function
+.variant_pcs foo
+foo:
+ ret
+.global bar
+.type bar, %function
+bar:
+ b foo
+EOF
+ libc_cv_aarch64_variant_pcs=no
+ if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles $no_ssp -shared -fPIC -o conftest.so conftest.S]) \
+ && AC_TRY_COMMAND([$READELF -dW conftest.so | grep -q AARCH64_VARIANT_PCS])
+ then
+ libc_cv_aarch64_variant_pcs=yes
+ fi
+ rm -rf conftest.*])
+LIBC_CONFIG_VAR([aarch64-variant-pcs], [$libc_cv_aarch64_variant_pcs])
new file mode 100644
@@ -0,0 +1,141 @@
+/* Record the register state before and after a variant PCS call.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <https://www.gnu.org/licenses/>. */
+
+ .variant_pcs vpcs_call
+ .global vpcs_call
+ .type vpcs_call, %function
+vpcs_call:
+ .cfi_startproc
+ hint 34 /* bti c. */
+
+ /* Save register state to *x0. */
+ stp x0, x1, [x0]
+ stp x2, x3, [x0, 16]
+ stp x4, x5, [x0, 32]
+ stp x6, x7, [x0, 48]
+ stp x8, x9, [x0, 64]
+ stp x10, x11, [x0, 80]
+ stp x12, x13, [x0, 96]
+ stp x14, x15, [x0, 112]
+ stp x16, x17, [x0, 128]
+ stp x18, x19, [x0, 144]
+ stp x20, x21, [x0, 160]
+ stp x22, x23, [x0, 176]
+ stp x24, x25, [x0, 192]
+ stp x26, x27, [x0, 208]
+ stp x28, x29, [x0, 224]
+ mov x1, sp
+ stp x30, x1, [x0, 240]
+ stp q0, q1, [x0, 256]
+ stp q2, q3, [x0, 288]
+ stp q4, q5, [x0, 320]
+ stp q6, q7, [x0, 352]
+ stp q8, q9, [x0, 384]
+ stp q10, q11, [x0, 416]
+ stp q12, q13, [x0, 448]
+ stp q14, q15, [x0, 480]
+ stp q16, q17, [x0, 512]
+ stp q18, q19, [x0, 544]
+ stp q20, q21, [x0, 576]
+ stp q22, q23, [x0, 608]
+ stp q24, q25, [x0, 640]
+ stp q26, q27, [x0, 672]
+ stp q28, q29, [x0, 704]
+ stp q30, q31, [x0, 736]
+ ret
+ .cfi_endproc
+ .size vpcs_call, .-vpcs_call
+
+ .global vpcs_call_regs
+ .type vpcs_call_regs, %function
+vpcs_call_regs:
+ .cfi_startproc
+ hint 34 /* bti c. */
+
+ stp x29, x30, [sp, -160]!
+ mov x29, sp
+
+ /* Save callee-saved registers. */
+ stp x19, x20, [sp, 16]
+ stp x21, x22, [sp, 32]
+ stp x23, x24, [sp, 48]
+ stp x25, x26, [sp, 64]
+ stp x27, x28, [sp, 80]
+ stp d8, d9, [sp, 96]
+ stp d10, d11, [sp, 112]
+ stp d12, d13, [sp, 128]
+ stp d14, d15, [sp, 144]
+
+ /* Initialize most registers from *x1, and save x0, x1, x29, x30,
+ and sp (== x29), so *x1 contains the register state. */
+ stp x0, x1, [x1]
+ str x29, [x1, 232]
+ ldp x2, x3, [x1, 16]
+ ldp x4, x5, [x1, 32]
+ ldp x6, x7, [x1, 48]
+ ldp x8, x9, [x1, 64]
+ ldp x10, x11, [x1, 80]
+ ldp x12, x13, [x1, 96]
+ ldp x14, x15, [x1, 112]
+ ldp x16, x17, [x1, 128]
+ ldp x18, x19, [x1, 144]
+ ldp x20, x21, [x1, 160]
+ ldp x22, x23, [x1, 176]
+ ldp x24, x25, [x1, 192]
+ ldp x26, x27, [x1, 208]
+ ldr x28, [x1, 224]
+ /* Skip x29, x30, sp. */
+ ldp q0, q1, [x1, 256]
+ ldp q2, q3, [x1, 288]
+ ldp q4, q5, [x1, 320]
+ ldp q6, q7, [x1, 352]
+ ldp q8, q9, [x1, 384]
+ ldp q10, q11, [x1, 416]
+ ldp q12, q13, [x1, 448]
+ ldp q14, q15, [x1, 480]
+ ldp q16, q17, [x1, 512]
+ ldp q18, q19, [x1, 544]
+ ldp q20, q21, [x1, 576]
+ ldp q22, q23, [x1, 608]
+ ldp q24, q25, [x1, 640]
+ ldp q26, q27, [x1, 672]
+ ldp q28, q29, [x1, 704]
+ ldp q30, q31, [x1, 736]
+
+ /* Emulate a BL using B, but save x30 before the branch. */
+ adr x30, .L_return_addr
+ stp x30, x29, [x1, 240]
+ b vpcs_call
+.L_return_addr:
+
+ /* Restore callee-saved registers. */
+ ldp x19, x20, [sp, 16]
+ ldp x21, x22, [sp, 32]
+ ldp x23, x24, [sp, 48]
+ ldp x25, x26, [sp, 64]
+ ldp x27, x28, [sp, 80]
+ ldp d8, d9, [sp, 96]
+ ldp d10, d11, [sp, 112]
+ ldp d12, d13, [sp, 128]
+ ldp d14, d15, [sp, 144]
+
+ ldp x29, x30, [sp], 160
+ ret
+ .cfi_endproc
+ .size vpcs_call_regs, .-vpcs_call_regs
new file mode 100644
@@ -0,0 +1,78 @@
+/* Test that variant PCS calls don't clobber registers with lazy binding.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <support/check.h>
+
+struct regs
+{
+ uint64_t x[32];
+ union {
+ long double q[32];
+ uint64_t u[64];
+ } v;
+};
+
+/* Gives the registers in the caller and callee around a variant PCS call.
+ Most registers are initialized from BEFORE in the caller so they can
+ have values that likely show clobbers. Register state extensions such
+ as SVE is not covered here, only the base registers. */
+void vpcs_call_regs (struct regs *after, struct regs *before);
+
+static int
+do_test (void)
+{
+ struct regs before, after;
+ int err = 0;
+
+ unsigned char *p = (unsigned char *)&before;
+ for (int i = 0; i < sizeof before; i++)
+ p[i] = i & 0xff;
+
+ vpcs_call_regs (&after, &before);
+
+ for (int i = 0; i < 32; i++)
+ if (before.x[i] != after.x[i])
+ {
+ if (i == 16 || i == 17)
+ /* Variant PCS allows clobbering x16 and x17. */
+ continue;
+ err++;
+ printf ("x%d: before: 0x%016llx after: 0x%016llx\n",
+ i,
+ (unsigned long long)before.x[i],
+ (unsigned long long)after.x[i]);
+ }
+ for (int i = 0; i < 64; i++)
+ if (before.v.u[i] != after.v.u[i])
+ {
+ err++;
+ printf ("v%d: before: 0x%016llx %016llx after: 0x%016llx %016llx\n",
+ i/2,
+ (unsigned long long)before.v.u[2*(i/2)+1],
+ (unsigned long long)before.v.u[2*(i/2)],
+ (unsigned long long)after.v.u[2*(i/2)+1],
+ (unsigned long long)after.v.u[2*(i/2)]);
+ }
+ if (err)
+ FAIL_EXIT1 ("The variant PCS call clobbered %d registers.\n", err);
+ return 0;
+}
+
+#include <support/test-driver.c>