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c175b21ce4
Bring in the fixes for GCC 7 through 13. https://rtx.meta.security/mitigation/2023/09/12/CVE-2023-4039.html https://developer.arm.com/Arm%20Security%20Center/GCC%20Stack%20Protector%20Vulnerability%20AArch64 Signed-off-by: Chris Packham <judge.packham@gmail.com>
300 lines
8.7 KiB
Diff
300 lines
8.7 KiB
Diff
From dad1c82acf67a8a1cc68e2acf3ec89a503e361fc Mon Sep 17 00:00:00 2001
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From: Richard Sandiford <richard.sandiford@arm.com>
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Date: Thu, 15 Jun 2023 19:16:52 +0100
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Subject: [PATCH 42/42] aarch64: Make stack smash canary protect saved
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registers
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AArch64 normally puts the saved registers near the bottom of the frame,
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immediately above any dynamic allocations. But this means that a
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stack-smash attack on those dynamic allocations could overwrite the
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saved registers without needing to reach as far as the stack smash
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canary.
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The same thing could also happen for variable-sized arguments that are
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passed by value, since those are allocated before a call and popped on
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return.
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This patch avoids that by putting the locals (and thus the canary) below
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the saved registers when stack smash protection is active.
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The patch fixes CVE-2023-4039.
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gcc/
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* config/aarch64/aarch64.c (aarch64_save_regs_above_locals_p):
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New function.
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(aarch64_layout_frame): Use it to decide whether locals should
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go above or below the saved registers.
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(aarch64_expand_prologue): Update stack layout comment.
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Emit a stack tie after the final adjustment.
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gcc/testsuite/
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* gcc.target/aarch64/stack-protector-8.c: New test.
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* gcc.target/aarch64/stack-protector-9.c: Likewise.
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---
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gcc/config/aarch64/aarch64.c | 47 +++++++--
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.../gcc.target/aarch64/stack-protector-8.c | 95 +++++++++++++++++++
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.../gcc.target/aarch64/stack-protector-9.c | 33 +++++++
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3 files changed, 169 insertions(+), 6 deletions(-)
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create mode 100644 gcc/testsuite/gcc.target/aarch64/stack-protector-8.c
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create mode 100644 gcc/testsuite/gcc.target/aarch64/stack-protector-9.c
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diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
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index 91833473c751..ce701b91a3f2 100644
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--- a/gcc/config/aarch64/aarch64.c
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+++ b/gcc/config/aarch64/aarch64.c
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@@ -6820,6 +6820,20 @@ aarch64_needs_frame_chain (void)
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return aarch64_use_frame_pointer;
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}
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+/* Return true if the current function should save registers above
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+ the locals area, rather than below it. */
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+
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+static bool
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+aarch64_save_regs_above_locals_p ()
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+{
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+ /* When using stack smash protection, make sure that the canary slot
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+ comes between the locals and the saved registers. Otherwise,
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+ it would be possible for a carefully sized smash attack to change
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+ the saved registers (particularly LR and FP) without reaching the
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+ canary. */
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+ return crtl->stack_protect_guard;
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+}
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+
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/* Mark the registers that need to be saved by the callee and calculate
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the size of the callee-saved registers area and frame record (both FP
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and LR may be omitted). */
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@@ -6831,6 +6845,7 @@ aarch64_layout_frame (void)
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poly_int64 vector_save_size = GET_MODE_SIZE (vector_save_mode);
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bool frame_related_fp_reg_p = false;
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aarch64_frame &frame = cfun->machine->frame;
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+ poly_int64 top_of_locals = -1;
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frame.emit_frame_chain = aarch64_needs_frame_chain ();
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@@ -6897,8 +6912,16 @@ aarch64_layout_frame (void)
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&& !crtl->abi->clobbers_full_reg_p (regno))
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frame.reg_offset[regno] = SLOT_REQUIRED;
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+ bool regs_at_top_p = aarch64_save_regs_above_locals_p ();
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+
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poly_int64 offset = crtl->outgoing_args_size;
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gcc_assert (multiple_p (offset, STACK_BOUNDARY / BITS_PER_UNIT));
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+ if (regs_at_top_p)
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+ {
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+ offset += get_frame_size ();
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+ offset = aligned_upper_bound (offset, STACK_BOUNDARY / BITS_PER_UNIT);
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+ top_of_locals = offset;
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+ }
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frame.bytes_below_saved_regs = offset;
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frame.sve_save_and_probe = INVALID_REGNUM;
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@@ -7043,15 +7066,18 @@ aarch64_layout_frame (void)
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at expand_prologue. */
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gcc_assert (crtl->is_leaf || maybe_ne (saved_regs_size, 0));
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- offset += get_frame_size ();
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- offset = aligned_upper_bound (offset, STACK_BOUNDARY / BITS_PER_UNIT);
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- poly_int64 top_of_locals = offset;
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-
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+ if (!regs_at_top_p)
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+ {
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+ offset += get_frame_size ();
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+ offset = aligned_upper_bound (offset, STACK_BOUNDARY / BITS_PER_UNIT);
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+ top_of_locals = offset;
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+ }
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offset += frame.saved_varargs_size;
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gcc_assert (multiple_p (offset, STACK_BOUNDARY / BITS_PER_UNIT));
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frame.frame_size = offset;
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frame.bytes_above_hard_fp = frame.frame_size - frame.bytes_below_hard_fp;
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+ gcc_assert (known_ge (top_of_locals, 0));
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frame.bytes_above_locals = frame.frame_size - top_of_locals;
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frame.initial_adjust = 0;
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@@ -8247,10 +8273,10 @@ aarch64_epilogue_uses (int regno)
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| for register varargs |
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| |
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+-------------------------------+
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- | local variables | <-- frame_pointer_rtx
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+ | local variables (1) | <-- frame_pointer_rtx
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| |
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+-------------------------------+
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- | padding |
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+ | padding (1) |
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+-------------------------------+
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| callee-saved registers |
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+-------------------------------+
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@@ -8262,6 +8288,10 @@ aarch64_epilogue_uses (int regno)
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+-------------------------------+
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| SVE predicate registers |
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+-------------------------------+
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+ | local variables (2) |
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+ +-------------------------------+
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+ | padding (2) |
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+ +-------------------------------+
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| dynamic allocation |
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+-------------------------------+
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| padding |
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@@ -8271,6 +8301,9 @@ aarch64_epilogue_uses (int regno)
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+-------------------------------+
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| | <-- stack_pointer_rtx (aligned)
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+ The regions marked (1) and (2) are mutually exclusive. (2) is used
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+ when aarch64_save_regs_above_locals_p is true.
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+
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Dynamic stack allocations via alloca() decrease stack_pointer_rtx
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but leave frame_pointer_rtx and hard_frame_pointer_rtx
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unchanged.
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@@ -8462,6 +8495,8 @@ aarch64_expand_prologue (void)
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gcc_assert (known_eq (bytes_below_sp, final_adjust));
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aarch64_allocate_and_probe_stack_space (tmp1_rtx, tmp0_rtx, final_adjust,
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!frame_pointer_needed, true);
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+ if (emit_frame_chain && maybe_ne (final_adjust, 0))
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+ emit_insn (gen_stack_tie (stack_pointer_rtx, hard_frame_pointer_rtx));
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}
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/* Return TRUE if we can use a simple_return insn.
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diff --git a/gcc/testsuite/gcc.target/aarch64/stack-protector-8.c b/gcc/testsuite/gcc.target/aarch64/stack-protector-8.c
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new file mode 100644
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index 000000000000..e71d820e3654
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/aarch64/stack-protector-8.c
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@@ -0,0 +1,95 @@
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+/* { dg-options " -O -fstack-protector-strong -mstack-protector-guard=sysreg -mstack-protector-guard-reg=tpidr2_el0 -mstack-protector-guard-offset=16" } */
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+/* { dg-final { check-function-bodies "**" "" } } */
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+
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+void g(void *);
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+__SVBool_t *h(void *);
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+
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+/*
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+** test1:
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+** sub sp, sp, #288
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+** stp x29, x30, \[sp, #?272\]
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+** add x29, sp, #?272
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+** mrs (x[0-9]+), tpidr2_el0
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+** ldr (x[0-9]+), \[\1, #?16\]
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+** str \2, \[sp, #?264\]
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+** mov \2, #?0
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+** add x0, sp, #?8
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+** bl g
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+** ...
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+** mrs .*
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+** ...
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+** bne .*
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+** ...
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+** ldp x29, x30, \[sp, #?272\]
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+** add sp, sp, #?288
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+** ret
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+** bl __stack_chk_fail
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+*/
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+int test1() {
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+ int y[0x40];
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+ g(y);
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+ return 1;
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+}
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+
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+/*
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+** test2:
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+** stp x29, x30, \[sp, #?-16\]!
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+** mov x29, sp
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+** sub sp, sp, #1040
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+** mrs (x[0-9]+), tpidr2_el0
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+** ldr (x[0-9]+), \[\1, #?16\]
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+** str \2, \[sp, #?1032\]
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+** mov \2, #?0
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+** add x0, sp, #?8
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+** bl g
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+** ...
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+** mrs .*
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+** ...
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+** bne .*
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+** ...
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+** add sp, sp, #?1040
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+** ldp x29, x30, \[sp\], #?16
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+** ret
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+** bl __stack_chk_fail
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+*/
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+int test2() {
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+ int y[0x100];
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+ g(y);
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+ return 1;
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+}
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+
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+#pragma GCC target "+sve"
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+
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+/*
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+** test3:
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+** stp x29, x30, \[sp, #?-16\]!
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+** mov x29, sp
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+** addvl sp, sp, #-18
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+** ...
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+** str p4, \[sp\]
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+** ...
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+** sub sp, sp, #272
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+** mrs (x[0-9]+), tpidr2_el0
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+** ldr (x[0-9]+), \[\1, #?16\]
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+** str \2, \[sp, #?264\]
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+** mov \2, #?0
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+** add x0, sp, #?8
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+** bl h
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+** ...
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+** mrs .*
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+** ...
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+** bne .*
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+** ...
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+** add sp, sp, #?272
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+** ...
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+** ldr p4, \[sp\]
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+** ...
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+** addvl sp, sp, #18
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+** ldp x29, x30, \[sp\], #?16
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+** ret
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+** bl __stack_chk_fail
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+*/
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+__SVBool_t test3() {
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+ int y[0x40];
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+ return *h(y);
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+}
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diff --git a/gcc/testsuite/gcc.target/aarch64/stack-protector-9.c b/gcc/testsuite/gcc.target/aarch64/stack-protector-9.c
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new file mode 100644
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index 000000000000..58f322aa480a
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/aarch64/stack-protector-9.c
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@@ -0,0 +1,33 @@
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+/* { dg-options "-O2 -mcpu=neoverse-v1 -fstack-protector-all" } */
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+/* { dg-final { check-function-bodies "**" "" } } */
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+
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+/*
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+** main:
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+** ...
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+** stp x29, x30, \[sp, #?-[0-9]+\]!
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+** ...
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+** sub sp, sp, #[0-9]+
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+** ...
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+** str x[0-9]+, \[x29, #?-8\]
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+** ...
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+*/
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+int f(const char *);
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+void g(void *);
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+int main(int argc, char* argv[])
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+{
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+ int a;
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+ int b;
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+ char c[2+f(argv[1])];
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+ int d[0x100];
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+ char y;
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+
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+ y=42; a=4; b=10;
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+ c[0] = 'h'; c[1] = '\0';
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+
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+ c[f(argv[2])] = '\0';
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+
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+ __builtin_printf("%d %d\n%s\n", a, b, c);
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+ g(d);
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+
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+ return 0;
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+}
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--
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2.42.0
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