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* [gcc(refs/users/giulianob/heads/pfe_backport_clean)] Backport [AArch64] PR92424: Fix -fpatchable-function-entry=N, M with BTI
@ 2021-10-19 18:40 Giuliano Belinassi
0 siblings, 0 replies; 2+ messages in thread
From: Giuliano Belinassi @ 2021-10-19 18:40 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:6d8714163cd0b94514ad8d1d98d17e99b00f3d2f
commit 6d8714163cd0b94514ad8d1d98d17e99b00f3d2f
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Wed Jan 15 12:23:40 2020 +0000
Backport [AArch64] PR92424: Fix -fpatchable-function-entry=N,M with BTI
This is a workaround that emits a BTI after the function label if that
is followed by a patch area. We try to remove the BTI that follows the
patch area (this may fail e.g. if the first instruction is a PACIASP).
So before this commit -fpatchable-function-entry=3,1 with bti generates
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
foo:
nop
nop
bti c // or paciasp
...
and after this commit
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
foo:
bti c
nop
nop
// may be paciasp
...
and with -fpatchable-function-entry=1 (M=0) the code now is
foo:
bti c
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
// may be paciasp
...
There is a new bti insn in the middle of the patchable area users need
to be aware of unless M=0 (patch area is after the new bti) or M=N
(patch area is before the label, no new bti). Note: bti is not added to
all functions consistently (it can be turned off per function using a
target attribute or the compiler may detect that the function is never
called indirectly), so if bti is inserted in the middle of a patch area
then user code needs to deal with detecting it.
Tested on aarch64-none-linux-gnu.
gcc/ChangeLog:
PR target/92424
* config/aarch64/aarch64.c (aarch64_declare_function_name): Set
cfun->machine->label_is_assembled.
(aarch64_print_patchable_function_entry): New.
(TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY): Define.
* config/aarch64/aarch64.h (struct machine_function): New field,
label_is_assembled.
gcc/testsuite/ChangeLog:
PR target/92424
* gcc.target/aarch64/pr92424-1.c: New test.
* gcc.target/aarch64/pr92424-2.c: New test.
* gcc.target/aarch64/pr92424-3.c: New test.
Diff:
---
gcc/config/aarch64/aarch64.c | 31 +++++++
gcc/config/aarch64/aarch64.h | 1 +
gcc/testsuite/gcc.target/aarch64/pr92424-1.c | 122 +++++++++++++++++++++++++++
gcc/testsuite/gcc.target/aarch64/pr92424-2.c | 12 +++
gcc/testsuite/gcc.target/aarch64/pr92424-3.c | 12 +++
5 files changed, 178 insertions(+)
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 4e94be3b0b4..744b436a54d 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -11753,6 +11753,34 @@ aarch64_declare_function_name (FILE *stream, const char* name,
/* Don't forget the type directive for ELF. */
ASM_OUTPUT_TYPE_DIRECTIVE (stream, name, "function");
ASM_OUTPUT_LABEL (stream, name);
+
+ cfun->machine->label_is_assembled = true;
+}
+
+/* Implement PRINT_PATCHABLE_FUNCTION_ENTRY. Check if the patch area is after
+ the function label and emit a BTI if necessary. */
+
+void
+aarch64_print_patchable_function_entry (FILE *file,
+ unsigned HOST_WIDE_INT patch_area_size,
+ bool record_p)
+{
+ if (cfun->machine->label_is_assembled
+ && aarch64_bti_enabled ()
+ && !cgraph_node::get (cfun->decl)->only_called_directly_p ())
+ {
+ /* Remove the BTI that follows the patch area and insert a new BTI
+ before the patch area right after the function label. */
+ rtx_insn *insn = next_real_nondebug_insn (get_insns ());
+ if (insn
+ && INSN_P (insn)
+ && GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE
+ && XINT (PATTERN (insn), 1) == UNSPECV_BTI_C)
+ delete_insn (insn);
+ asm_fprintf (file, "\thint\t34 // bti c\n");
+ }
+
+ default_print_patchable_function_entry (file, patch_area_size, record_p);
}
/* Implements TARGET_ASM_FILE_START. Output the assembly header. */
@@ -14779,6 +14807,9 @@ aarch64_run_selftests (void)
#undef TARGET_ASM_TRAMPOLINE_TEMPLATE
#define TARGET_ASM_TRAMPOLINE_TEMPLATE aarch64_asm_trampoline_template
+#undef TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY
+#define TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY aarch64_print_patchable_function_entry
+
#undef TARGET_BUILD_BUILTIN_VA_LIST
#define TARGET_BUILD_BUILTIN_VA_LIST aarch64_build_builtin_va_list
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index ddf833ebfe8..8cac2da1070 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -601,6 +601,7 @@ typedef struct GTY (()) machine_function
struct aarch64_frame frame;
/* One entry for each hard register. */
bool reg_is_wrapped_separately[LAST_SAVED_REGNUM];
+ bool label_is_assembled;
} machine_function;
#endif
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-1.c b/gcc/testsuite/gcc.target/aarch64/pr92424-1.c
new file mode 100644
index 00000000000..c413a2c306e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-1.c
@@ -0,0 +1,122 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+/* { dg-final { check-function-bodies "**" "" } } */
+
+/* Note: this test only checks the instructions in the function bodies,
+ not the placement of the patch label or nops before the futncion. */
+
+/*
+**f10_none:
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (1, 0)))
+f10_none ()
+{
+}
+
+/*
+**f10_pac:
+** hint 34 // bti c
+** nop
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 0)))
+f10_pac ()
+{
+}
+
+/*
+**f10_bti:
+** hint 34 // bti c
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 0)))
+f10_bti ()
+{
+}
+
+/*
+**f11_none:
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (1, 1)))
+f11_none ()
+{
+}
+
+/*
+**f11_pac:
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 1)))
+f11_pac ()
+{
+}
+
+/*
+**f11_bti:
+** hint 34 // bti c
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 1)))
+f11_bti ()
+{
+}
+
+/*
+**f21_none:
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (2, 1)))
+f21_none ()
+{
+}
+
+/*
+**f21_pac:
+** hint 34 // bti c
+** nop
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (2, 1)))
+f21_pac ()
+{
+}
+
+/*
+**f21_bti:
+** hint 34 // bti c
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (2, 1)))
+f21_bti ()
+{
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
new file mode 100644
index 00000000000..0e75657a153
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+
+/* Test the placement of the .LPFE1 label. */
+
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 0)))
+f10_bti ()
+{
+}
+/* { dg-final { scan-assembler "f10_bti:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
new file mode 100644
index 00000000000..0a1f74d4096
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+
+/* Test the placement of the .LPFE1 label. */
+
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 0)))
+f10_pac ()
+{
+}
+/* { dg-final { scan-assembler "f10_pac:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
^ permalink raw reply [flat|nested] 2+ messages in thread
* [gcc(refs/users/giulianob/heads/pfe_backport_clean)] Backport [AArch64] PR92424: Fix -fpatchable-function-entry=N, M with BTI
@ 2021-10-19 18:12 Giuliano Belinassi
0 siblings, 0 replies; 2+ messages in thread
From: Giuliano Belinassi @ 2021-10-19 18:12 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d8467ff619da4cbf13bb0f154492d7dcd8c88eba
commit d8467ff619da4cbf13bb0f154492d7dcd8c88eba
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Wed Jan 15 12:23:40 2020 +0000
Backport [AArch64] PR92424: Fix -fpatchable-function-entry=N,M with BTI
This is a workaround that emits a BTI after the function label if that
is followed by a patch area. We try to remove the BTI that follows the
patch area (this may fail e.g. if the first instruction is a PACIASP).
So before this commit -fpatchable-function-entry=3,1 with bti generates
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
foo:
nop
nop
bti c // or paciasp
...
and after this commit
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
foo:
bti c
nop
nop
// may be paciasp
...
and with -fpatchable-function-entry=1 (M=0) the code now is
foo:
bti c
.section __patchable_function_entries
.8byte .LPFE
.text
.LPFE:
nop
// may be paciasp
...
There is a new bti insn in the middle of the patchable area users need
to be aware of unless M=0 (patch area is after the new bti) or M=N
(patch area is before the label, no new bti). Note: bti is not added to
all functions consistently (it can be turned off per function using a
target attribute or the compiler may detect that the function is never
called indirectly), so if bti is inserted in the middle of a patch area
then user code needs to deal with detecting it.
Tested on aarch64-none-linux-gnu.
gcc/ChangeLog:
PR target/92424
* config/aarch64/aarch64.c (aarch64_declare_function_name): Set
cfun->machine->label_is_assembled.
(aarch64_print_patchable_function_entry): New.
(TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY): Define.
* config/aarch64/aarch64.h (struct machine_function): New field,
label_is_assembled.
gcc/testsuite/ChangeLog:
PR target/92424
* gcc.target/aarch64/pr92424-1.c: New test.
* gcc.target/aarch64/pr92424-2.c: New test.
* gcc.target/aarch64/pr92424-3.c: New test.
Diff:
---
gcc/config/aarch64/aarch64.c | 31 +++++++
gcc/config/aarch64/aarch64.h | 1 +
gcc/testsuite/gcc.target/aarch64/pr92424-1.c | 122 +++++++++++++++++++++++++++
gcc/testsuite/gcc.target/aarch64/pr92424-2.c | 12 +++
gcc/testsuite/gcc.target/aarch64/pr92424-3.c | 12 +++
5 files changed, 178 insertions(+)
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 4e94be3b0b4..744b436a54d 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -11753,6 +11753,34 @@ aarch64_declare_function_name (FILE *stream, const char* name,
/* Don't forget the type directive for ELF. */
ASM_OUTPUT_TYPE_DIRECTIVE (stream, name, "function");
ASM_OUTPUT_LABEL (stream, name);
+
+ cfun->machine->label_is_assembled = true;
+}
+
+/* Implement PRINT_PATCHABLE_FUNCTION_ENTRY. Check if the patch area is after
+ the function label and emit a BTI if necessary. */
+
+void
+aarch64_print_patchable_function_entry (FILE *file,
+ unsigned HOST_WIDE_INT patch_area_size,
+ bool record_p)
+{
+ if (cfun->machine->label_is_assembled
+ && aarch64_bti_enabled ()
+ && !cgraph_node::get (cfun->decl)->only_called_directly_p ())
+ {
+ /* Remove the BTI that follows the patch area and insert a new BTI
+ before the patch area right after the function label. */
+ rtx_insn *insn = next_real_nondebug_insn (get_insns ());
+ if (insn
+ && INSN_P (insn)
+ && GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE
+ && XINT (PATTERN (insn), 1) == UNSPECV_BTI_C)
+ delete_insn (insn);
+ asm_fprintf (file, "\thint\t34 // bti c\n");
+ }
+
+ default_print_patchable_function_entry (file, patch_area_size, record_p);
}
/* Implements TARGET_ASM_FILE_START. Output the assembly header. */
@@ -14779,6 +14807,9 @@ aarch64_run_selftests (void)
#undef TARGET_ASM_TRAMPOLINE_TEMPLATE
#define TARGET_ASM_TRAMPOLINE_TEMPLATE aarch64_asm_trampoline_template
+#undef TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY
+#define TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY aarch64_print_patchable_function_entry
+
#undef TARGET_BUILD_BUILTIN_VA_LIST
#define TARGET_BUILD_BUILTIN_VA_LIST aarch64_build_builtin_va_list
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index ddf833ebfe8..8cac2da1070 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -601,6 +601,7 @@ typedef struct GTY (()) machine_function
struct aarch64_frame frame;
/* One entry for each hard register. */
bool reg_is_wrapped_separately[LAST_SAVED_REGNUM];
+ bool label_is_assembled;
} machine_function;
#endif
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-1.c b/gcc/testsuite/gcc.target/aarch64/pr92424-1.c
new file mode 100644
index 00000000000..c413a2c306e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-1.c
@@ -0,0 +1,122 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+/* { dg-final { check-function-bodies "**" "" } } */
+
+/* Note: this test only checks the instructions in the function bodies,
+ not the placement of the patch label or nops before the futncion. */
+
+/*
+**f10_none:
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (1, 0)))
+f10_none ()
+{
+}
+
+/*
+**f10_pac:
+** hint 34 // bti c
+** nop
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 0)))
+f10_pac ()
+{
+}
+
+/*
+**f10_bti:
+** hint 34 // bti c
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 0)))
+f10_bti ()
+{
+}
+
+/*
+**f11_none:
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (1, 1)))
+f11_none ()
+{
+}
+
+/*
+**f11_pac:
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 1)))
+f11_pac ()
+{
+}
+
+/*
+**f11_bti:
+** hint 34 // bti c
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 1)))
+f11_bti ()
+{
+}
+
+/*
+**f21_none:
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=none"),
+ patchable_function_entry (2, 1)))
+f21_none ()
+{
+}
+
+/*
+**f21_pac:
+** hint 34 // bti c
+** nop
+** hint 25 // paciasp
+** hint 29 // autiasp
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (2, 1)))
+f21_pac ()
+{
+}
+
+/*
+**f21_bti:
+** hint 34 // bti c
+** nop
+** ret
+*/
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (2, 1)))
+f21_bti ()
+{
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
new file mode 100644
index 00000000000..0e75657a153
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+
+/* Test the placement of the .LPFE1 label. */
+
+void
+__attribute__ ((target("branch-protection=bti"),
+ patchable_function_entry (1, 0)))
+f10_bti ()
+{
+}
+/* { dg-final { scan-assembler "f10_bti:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
new file mode 100644
index 00000000000..0a1f74d4096
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+
+/* Test the placement of the .LPFE1 label. */
+
+void
+__attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
+ patchable_function_entry (1, 0)))
+f10_pac ()
+{
+}
+/* { dg-final { scan-assembler "f10_pac:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
^ permalink raw reply [flat|nested] 2+ messages in thread
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