diff options
Diffstat (limited to '0117-aarch64-Tweak-stack-clash-boundary-condition.patch')
| -rw-r--r-- | 0117-aarch64-Tweak-stack-clash-boundary-condition.patch | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/0117-aarch64-Tweak-stack-clash-boundary-condition.patch b/0117-aarch64-Tweak-stack-clash-boundary-condition.patch new file mode 100644 index 0000000..826f53e --- /dev/null +++ b/0117-aarch64-Tweak-stack-clash-boundary-condition.patch @@ -0,0 +1,124 @@ +From af6bac9775e7d2bc94e4e3600740c3c475e117b5 Mon Sep 17 00:00:00 2001 +From: Richard Sandiford <richard.sandiford@arm.com> +Date: Tue, 27 Jun 2023 15:11:44 +0100 +Subject: [PATCH] aarch64: Tweak stack clash boundary condition + +The AArch64 ABI says that, when stack clash protection is used, +there can be a maximum of 1KiB of unprobed space at sp on entry +to a function. Therefore, we need to probe when allocating +>= guard_size - 1KiB of data (>= rather than >). This is what +GCC does. + +If an allocation is exactly guard_size bytes, it is enough to allocate +those bytes and probe once at offset 1024. It isn't possible to use a +single probe at any other offset: higher would conmplicate later code, +by leaving more unprobed space than usual, while lower would risk +leaving an entire page unprobed. For simplicity, the code probes all +allocations at offset 1024. + +Some register saves also act as probes. If we need to allocate +more space below the last such register save probe, we need to +probe the allocation if it is > 1KiB. Again, this allocation is +then sometimes (but not always) probed at offset 1024. This sort of +allocation is currently only used for outgoing arguments, which are +rarely this big. + +However, the code also probed if this final outgoing-arguments +allocation was == 1KiB, rather than just > 1KiB. This isn't +necessary, since the register save then probes at offset 1024 +as required. Continuing to probe allocations of exactly 1KiB +would complicate later patches. + +gcc/ + * config/aarch64/aarch64.c (aarch64_allocate_and_probe_stack_space): + Don't probe final allocations that are exactly 1KiB in size (after + unprobed space above the final allocation has been deducted). + +gcc/testsuite/ + * gcc.target/aarch64/stack-check-prologue-17.c: New test. +--- + gcc/config/aarch64/aarch64.c | 4 +- + .../aarch64/stack-check-prologue-17.c | 55 +++++++++++++++++++ + 2 files changed, 58 insertions(+), 1 deletion(-) + create mode 100644 gcc/testsuite/gcc.target/aarch64/stack-check-prologue-17.c + +diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c +index 08a8667bbc1..43240af8ae4 100644 +--- a/gcc/config/aarch64/aarch64.c ++++ b/gcc/config/aarch64/aarch64.c +@@ -7962,9 +7962,11 @@ aarch64_allocate_and_probe_stack_space (rtx temp1, rtx temp2, + HOST_WIDE_INT guard_size + = 1 << param_stack_clash_protection_guard_size; + HOST_WIDE_INT guard_used_by_caller = STACK_CLASH_CALLER_GUARD; ++ HOST_WIDE_INT byte_sp_alignment = STACK_BOUNDARY / BITS_PER_UNIT; ++ gcc_assert (multiple_p (poly_size, byte_sp_alignment)); + HOST_WIDE_INT min_probe_threshold + = (final_adjustment_p +- ? guard_used_by_caller ++ ? guard_used_by_caller + byte_sp_alignment + : guard_size - guard_used_by_caller); + /* When doing the final adjustment for the outgoing arguments, take into + account any unprobed space there is above the current SP. There are +diff --git a/gcc/testsuite/gcc.target/aarch64/stack-check-prologue-17.c b/gcc/testsuite/gcc.target/aarch64/stack-check-prologue-17.c +new file mode 100644 +index 00000000000..0d8a25d73a2 +--- /dev/null ++++ b/gcc/testsuite/gcc.target/aarch64/stack-check-prologue-17.c +@@ -0,0 +1,55 @@ ++/* { dg-options "-O2 -fstack-clash-protection -fomit-frame-pointer --param stack-clash-protection-guard-size=12" } */ ++/* { dg-final { check-function-bodies "**" "" } } */ ++ ++void f(int, ...); ++void g(); ++ ++/* ++** test1: ++** ... ++** str x30, \[sp\] ++** sub sp, sp, #1024 ++** cbnz w0, .* ++** bl g ++** ... ++*/ ++int test1(int z) { ++ __uint128_t x = 0; ++ int y[0x400]; ++ if (z) ++ { ++ f(0, 0, 0, 0, 0, 0, 0, &y, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x); ++ } ++ g(); ++ return 1; ++} ++ ++/* ++** test2: ++** ... ++** str x30, \[sp\] ++** sub sp, sp, #1040 ++** str xzr, \[sp\] ++** cbnz w0, .* ++** bl g ++** ... ++*/ ++int test2(int z) { ++ __uint128_t x = 0; ++ int y[0x400]; ++ if (z) ++ { ++ f(0, 0, 0, 0, 0, 0, 0, &y, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, ++ x); ++ } ++ g(); ++ return 1; ++} +-- +2.39.3 |