RE: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Hi James
-Original Message-
From: James Greenhalgh
Sent: 18 April 2019 09:56
To: Sudakshina Das
Cc: Richard Henderson ; H.J. Lu
; Richard Henderson ;
gcc-patches@gcc.gnu.org; nd ; Richard Earnshaw
; Marcus Shawcroft ;
ni...@redhat.com
Subject: Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
On Thu, Apr 04, 2019 at 05:01:06PM +0100, Sudakshina Das wrote:
> Hi Richard
>
> On 03/04/2019 11:28, Richard Henderson wrote:
> > On 4/3/19 5:19 PM, Sudakshina Das wrote:
> >> + /* PT_NOTE header: namesz, descsz, type.
> >> + namesz = 4 ("GNU\0")
> >> + descsz = 16 (Size of the program property array)
> >> + type = 5 (NT_GNU_PROPERTY_TYPE_0). */
> >> + assemble_align (POINTER_SIZE);
> >> + assemble_integer (GEN_INT (4), 4, 32, 1);
> >> + assemble_integer (GEN_INT (16), 4, 32, 1);
> >
> > So, it's 16 only if POINTER_SIZE == 64.
> >
> > I think ROUND_UP (12, POINTER_BYTES) is what you want here.
> >
>
>
> Ah yes. I have made that change now.
This is OK, but instead of:
> diff --git a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> index
> e8e3cdac51350b545e5c2a644a3e1f4d1c37f88d..1fe92ff08935d4c6f08affcbd77e
> a91537030640 100644
> --- a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> +++ b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> @@ -4,7 +4,9 @@
> int
> f (int a, ...)
> {
> - /* { dg-final { scan-assembler-not "str" } } */
> + /* Fails on aarch64*-*-linux* if configured with
> +--enable-standard-branch-protection because of the GNU NOTE
> + section. */
> + /* { dg-final { scan-assembler-not "str" { target { !
> + aarch64*-*-linux* } || { ! default_branch_protection } } } } */
>return a;
> }
> Can you just change the regex to check for str followed by a tab, or
> something that looks else which looks like the instruction and doesn't match
> against 'string'.
>Thanks,
>James
Ah yes, I have reduced the diff in this test to only update the scan directive
to look for 'str\t' instead.
Committed as r270515.
Thanks
Sudi
>
> Thanks
> Sudi
>
> >
> > r~
> >
>
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
On Thu, Apr 04, 2019 at 05:01:06PM +0100, Sudakshina Das wrote:
> Hi Richard
>
> On 03/04/2019 11:28, Richard Henderson wrote:
> > On 4/3/19 5:19 PM, Sudakshina Das wrote:
> >> + /* PT_NOTE header: namesz, descsz, type.
> >> + namesz = 4 ("GNU\0")
> >> + descsz = 16 (Size of the program property array)
> >> + type = 5 (NT_GNU_PROPERTY_TYPE_0). */
> >> + assemble_align (POINTER_SIZE);
> >> + assemble_integer (GEN_INT (4), 4, 32, 1);
> >> + assemble_integer (GEN_INT (16), 4, 32, 1);
> >
> > So, it's 16 only if POINTER_SIZE == 64.
> >
> > I think ROUND_UP (12, POINTER_BYTES) is what you want here.
> >
>
>
> Ah yes. I have made that change now.
This is OK, but instead of:
> diff --git a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> index
> e8e3cdac51350b545e5c2a644a3e1f4d1c37f88d..1fe92ff08935d4c6f08affcbd77ea91537030640
> 100644
> --- a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> +++ b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
> @@ -4,7 +4,9 @@
> int
> f (int a, ...)
> {
> - /* { dg-final { scan-assembler-not "str" } } */
> + /* Fails on aarch64*-*-linux* if configured with
> +--enable-standard-branch-protection because of the GNU NOTE section. */
> + /* { dg-final { scan-assembler-not "str" { target { ! aarch64*-*-linux* }
> || { ! default_branch_protection } } } } */
>return a;
> }
Can you just change the regex to check for str followed by a tab, or
something that looks else which looks like the instruction and doesn't
match against 'string'.
Thanks,
James
>
> Thanks
> Sudi
>
> >
> > r~
> >
>
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Ping.
On 04/04/2019 17:01, Sudakshina Das wrote:
> Hi Richard
>
> On 03/04/2019 11:28, Richard Henderson wrote:
>> On 4/3/19 5:19 PM, Sudakshina Das wrote:
>>> + /* PT_NOTE header: namesz, descsz, type.
>>> + namesz = 4 ("GNU\0")
>>> + descsz = 16 (Size of the program property array)
>>> + type = 5 (NT_GNU_PROPERTY_TYPE_0). */
>>> + assemble_align (POINTER_SIZE);
>>> + assemble_integer (GEN_INT (4), 4, 32, 1);
>>> + assemble_integer (GEN_INT (16), 4, 32, 1);
>>
>> So, it's 16 only if POINTER_SIZE == 64.
>>
>> I think ROUND_UP (12, POINTER_BYTES) is what you want here.
>>
>
>
> Ah yes. I have made that change now.
>
> Thanks
> Sudi
>
>>
>> r~
>>
>
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Hi Richard
On 03/04/2019 11:28, Richard Henderson wrote:
> On 4/3/19 5:19 PM, Sudakshina Das wrote:
>> + /* PT_NOTE header: namesz, descsz, type.
>> + namesz = 4 ("GNU\0")
>> + descsz = 16 (Size of the program property array)
>> + type = 5 (NT_GNU_PROPERTY_TYPE_0). */
>> + assemble_align (POINTER_SIZE);
>> + assemble_integer (GEN_INT (4), 4, 32, 1);
>> + assemble_integer (GEN_INT (16), 4, 32, 1);
>
> So, it's 16 only if POINTER_SIZE == 64.
>
> I think ROUND_UP (12, POINTER_BYTES) is what you want here.
>
Ah yes. I have made that change now.
Thanks
Sudi
>
> r~
>
diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h
index 9d0292d64f20939ccedd7ab56027aa1282826b23..5e8b34ded03c78493f868e38647bf57c2da5187c 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -83,7 +83,7 @@
#define GNU_USER_TARGET_D_CRITSEC_SIZE 48
-#define TARGET_ASM_FILE_END file_end_indicate_exec_stack
+#define TARGET_ASM_FILE_END aarch64_file_end_indicate_exec_stack
/* Uninitialized common symbols in non-PIE executables, even with
strong definitions in dependent shared libraries, will resolve
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index b38505b0872688634b2d3f625ab8d313e89cfca0..83b8ef84808c19fa1214fa06c32957936f5eb520 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -18744,6 +18744,57 @@ aarch64_stack_protect_guard (void)
return NULL_TREE;
}
+/* Implement TARGET_ASM_FILE_END for AArch64. This adds the AArch64 GNU NOTE
+ section at the end if needed. */
+#define GNU_PROPERTY_AARCH64_FEATURE_1_AND 0xc000
+#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI (1U << 0)
+#define GNU_PROPERTY_AARCH64_FEATURE_1_PAC (1U << 1)
+void
+aarch64_file_end_indicate_exec_stack ()
+{
+ file_end_indicate_exec_stack ();
+
+ unsigned feature_1_and = 0;
+ if (aarch64_bti_enabled ())
+feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
+
+ if (aarch64_ra_sign_scope != AARCH64_FUNCTION_NONE)
+feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
+
+ if (feature_1_and)
+{
+ /* Generate .note.gnu.property section. */
+ switch_to_section (get_section (".note.gnu.property",
+ SECTION_NOTYPE, NULL));
+
+ /* PT_NOTE header: namesz, descsz, type.
+ namesz = 4 ("GNU\0")
+ descsz = 16 (Size of the program property array)
+ [(12 + padding) * Number of array elements]
+ type = 5 (NT_GNU_PROPERTY_TYPE_0). */
+ assemble_align (POINTER_SIZE);
+ assemble_integer (GEN_INT (4), 4, 32, 1);
+ assemble_integer (GEN_INT (ROUND_UP (12, POINTER_BYTES)), 4, 32, 1);
+ assemble_integer (GEN_INT (5), 4, 32, 1);
+
+ /* PT_NOTE name. */
+ assemble_string ("GNU", 4);
+
+ /* PT_NOTE contents for NT_GNU_PROPERTY_TYPE_0:
+ type = GNU_PROPERTY_AARCH64_FEATURE_1_AND
+ datasz = 4
+ data = feature_1_and. */
+ assemble_integer (GEN_INT (GNU_PROPERTY_AARCH64_FEATURE_1_AND), 4, 32, 1);
+ assemble_integer (GEN_INT (4), 4, 32, 1);
+ assemble_integer (GEN_INT (feature_1_and), 4, 32, 1);
+
+ /* Pad the size of the note to the required alignment. */
+ assemble_align (POINTER_SIZE);
+}
+}
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_PAC
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_BTI
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_AND
/* Target-specific selftests. */
diff --git a/gcc/testsuite/gcc.target/aarch64/bti-1.c b/gcc/testsuite/gcc.target/aarch64/bti-1.c
index a8c60412e310a4f322372f334ae5314f426d310e..5a556b08ed15679b25676a11fe9c7a64641ee671 100644
--- a/gcc/testsuite/gcc.target/aarch64/bti-1.c
+++ b/gcc/testsuite/gcc.target/aarch64/bti-1.c
@@ -61,3 +61,4 @@ lab2:
}
/* { dg-final { scan-assembler-times "hint\t34" 1 } } */
/* { dg-final { scan-assembler-times "hint\t36" 12 } } */
+/* { dg-final { scan-assembler ".note.gnu.property" { target *-*-linux* } } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
index e8e3cdac51350b545e5c2a644a3e1f4d1c37f88d..1fe92ff08935d4c6f08affcbd77ea91537030640 100644
--- a/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/va_arg_1.c
@@ -4,7 +4,9 @@
int
f (int a, ...)
{
- /* { dg-final { scan-assembler-not "str" } } */
+ /* Fails on aarch64*-*-linux* if configured with
+--enable-standard-branch-protection because of the GNU NOTE section. */
+ /* { dg-final { scan-assembler-not "str" { target { ! aarch64*-*-linux* } || { ! default_branch_protection } } } } */
return a;
}
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
On 4/3/19 5:19 PM, Sudakshina Das wrote:
> + /* PT_NOTE header: namesz, descsz, type.
> + namesz = 4 ("GNU\0")
> + descsz = 16 (Size of the program property array)
> + type = 5 (NT_GNU_PROPERTY_TYPE_0). */
> + assemble_align (POINTER_SIZE);
> + assemble_integer (GEN_INT (4), 4, 32, 1);
> + assemble_integer (GEN_INT (16), 4, 32, 1);
So, it's 16 only if POINTER_SIZE == 64.
I think ROUND_UP (12, POINTER_BYTES) is what you want here.
r~
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Hi Richard
On 02/04/2019 10:25, Sudakshina Das wrote:
> Hi
>
> On 02/04/2019 03:27, H.J. Lu wrote:
>> On Tue, Apr 2, 2019 at 10:05 AM Richard Henderson
>> wrote:
>>>
>>> On 4/1/19 8:53 PM, Sudakshina Das wrote:
> This could stand to use a comment, a moment's thinking about the
> sizes, and to
> use the existing asm output functions.
>
> /* PT_NOTE header: namesz, descsz, type.
> namesz = 4 ("GNU\0")
> descsz = 12 (see below)
I was trying out these changes but the descsz of 12 gets rejected by
readelf. It hits the following
unsigned int size = is_32bit_elf ? 4 : 8;
printf (_(" Properties: "));
if (pnote->descsz < 8 || (pnote->descsz % size) != 0)
{
printf (_("\n"),
pnote->descsz);
return;
}
>>>
>>> Hmm, interesting. The docs say that padding is not to be included in
>>> descsz
>>> (gabi4.1, page 82). To my eye this is a bug in binutils, but perhaps
>>> we will
>>> have to live with it.
>>>
>>> Nick, thoughts?
>>
>> descsz is wrong. From:
>>
>> https://github.com/hjl-tools/linux-abi/wiki/Linux-Extensions-to-gABI
>>
>> n_desc The note descriptor. The first n_descsz bytes in n_desc is the
>> pro-
>> gram property array.
>>
>> The program property array
>> Each array element represents one program property with type, data
>> size and data.
>> In 64-bit objects, each element is an array of 8-byte integers in the
>> format of the
>> target processor. In 32-bit objects, each element is an array of
>> 4-byte integers in
>> the format of the target processor.
>
> Thanks @HJ for clarifying that. I should have been more careful in
> spotting the difference.
>
> @Richard I will update my patch according to your suggestions but
> keeping in mind decssz should be the size of the entire program property
> array so 16 in this case.
>
I have updated the patch as per your suggestions. The Changelog is still
valid from my original patch.
Thanks
Sudi
> Thanks
> Sudi
>>
>>
>
diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h
index 9d0292d64f20939ccedd7ab56027aa1282826b23..5e8b34ded03c78493f868e38647bf57c2da5187c 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -83,7 +83,7 @@
#define GNU_USER_TARGET_D_CRITSEC_SIZE 48
-#define TARGET_ASM_FILE_END file_end_indicate_exec_stack
+#define TARGET_ASM_FILE_END aarch64_file_end_indicate_exec_stack
/* Uninitialized common symbols in non-PIE executables, even with
strong definitions in dependent shared libraries, will resolve
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index b38505b0872688634b2d3f625ab8d313e89cfca0..f25f7da8f0224167db68e61a2ba88f0943316360 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -18744,6 +18744,56 @@ aarch64_stack_protect_guard (void)
return NULL_TREE;
}
+/* Implement TARGET_ASM_FILE_END for AArch64. This adds the AArch64 GNU NOTE
+ section at the end if needed. */
+#define GNU_PROPERTY_AARCH64_FEATURE_1_AND 0xc000
+#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI (1U << 0)
+#define GNU_PROPERTY_AARCH64_FEATURE_1_PAC (1U << 1)
+void
+aarch64_file_end_indicate_exec_stack ()
+{
+ file_end_indicate_exec_stack ();
+
+ unsigned feature_1_and = 0;
+ if (aarch64_bti_enabled ())
+feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
+
+ if (aarch64_ra_sign_scope != AARCH64_FUNCTION_NONE)
+feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
+
+ if (feature_1_and)
+{
+ /* Generate .note.gnu.property section. */
+ switch_to_section (get_section (".note.gnu.property",
+ SECTION_NOTYPE, NULL));
+
+ /* PT_NOTE header: namesz, descsz, type.
+ namesz = 4 ("GNU\0")
+ descsz = 16 (Size of the program property array)
+ type = 5 (NT_GNU_PROPERTY_TYPE_0). */
+ assemble_align (POINTER_SIZE);
+ assemble_integer (GEN_INT (4), 4, 32, 1);
+ assemble_integer (GEN_INT (16), 4, 32, 1);
+ assemble_integer (GEN_INT (5), 4, 32, 1);
+
+ /* PT_NOTE name. */
+ assemble_string ("GNU", 4);
+
+ /* PT_NOTE contents for NT_GNU_PROPERTY_TYPE_0:
+ type = GNU_PROPERTY_AARCH64_FEATURE_1_AND
+ datasz = 4
+ data = feature_1_and. */
+ assemble_integer (GEN_INT (GNU_PROPERTY_AARCH64_FEATURE_1_AND), 4, 32, 1);
+ assemble_integer (GEN_INT (4), 4, 32, 1);
+ assemble_integer (GEN_INT (feature_1_and), 4, 32, 1);
+
+ /* Pad the size of the note to the required alignment. */
+ assemble_align (POINTER_SIZE);
+}
+}
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_PAC
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_BTI
+#undef GNU_PROPERTY_AARCH64_FEATURE_1_AND
/* Target-specific selftests. */
diff --git a/gcc/testsuite/gcc.target/aarch64/bti-1.c b/gcc/testsuite/gcc.target/aarch64/bti-1.c
index
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Hi
On 02/04/2019 03:27, H.J. Lu wrote:
> On Tue, Apr 2, 2019 at 10:05 AM Richard Henderson wrote:
>>
>> On 4/1/19 8:53 PM, Sudakshina Das wrote:
This could stand to use a comment, a moment's thinking about the sizes,
and to
use the existing asm output functions.
/* PT_NOTE header: namesz, descsz, type.
namesz = 4 ("GNU\0")
descsz = 12 (see below)
>>> I was trying out these changes but the descsz of 12 gets rejected by
>>> readelf. It hits the following
>>>
>>> unsigned intsize = is_32bit_elf ? 4 : 8;
>>>
>>> printf (_(" Properties: "));
>>>
>>> if (pnote->descsz < 8 || (pnote->descsz % size) != 0)
>>> {
>>> printf (_("\n"),
>>> pnote->descsz);
>>> return;
>>> }
>>
>> Hmm, interesting. The docs say that padding is not to be included in descsz
>> (gabi4.1, page 82). To my eye this is a bug in binutils, but perhaps we will
>> have to live with it.
>>
>> Nick, thoughts?
>
> descsz is wrong. From:
>
> https://github.com/hjl-tools/linux-abi/wiki/Linux-Extensions-to-gABI
>
> n_desc The note descriptor. The first n_descsz bytes in n_desc is the pro-
> gram property array.
>
> The program property array
> Each array element represents one program property with type, data
> size and data.
> In 64-bit objects, each element is an array of 8-byte integers in the
> format of the
> target processor. In 32-bit objects, each element is an array of
> 4-byte integers in
> the format of the target processor.
Thanks @HJ for clarifying that. I should have been more careful in
spotting the difference.
@Richard I will update my patch according to your suggestions but
keeping in mind decssz should be the size of the entire program property
array so 16 in this case.
Thanks
Sudi
>
>
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
On Tue, Apr 2, 2019 at 10:05 AM Richard Henderson wrote:
>
> On 4/1/19 8:53 PM, Sudakshina Das wrote:
> >> This could stand to use a comment, a moment's thinking about the sizes,
> >> and to
> >> use the existing asm output functions.
> >>
> >> /* PT_NOTE header: namesz, descsz, type.
> >> namesz = 4 ("GNU\0")
> >> descsz = 12 (see below)
> > I was trying out these changes but the descsz of 12 gets rejected by
> > readelf. It hits the following
> >
> >unsigned intsize = is_32bit_elf ? 4 : 8;
> >
> >printf (_(" Properties: "));
> >
> >if (pnote->descsz < 8 || (pnote->descsz % size) != 0)
> > {
> >printf (_("\n"),
> > pnote->descsz);
> >return;
> > }
>
> Hmm, interesting. The docs say that padding is not to be included in descsz
> (gabi4.1, page 82). To my eye this is a bug in binutils, but perhaps we will
> have to live with it.
>
> Nick, thoughts?
descsz is wrong. From:
https://github.com/hjl-tools/linux-abi/wiki/Linux-Extensions-to-gABI
n_desc The note descriptor. The first n_descsz bytes in n_desc is the pro-
gram property array.
The program property array
Each array element represents one program property with type, data
size and data.
In 64-bit objects, each element is an array of 8-byte integers in the
format of the
target processor. In 32-bit objects, each element is an array of
4-byte integers in
the format of the target processor.
--
H.J.
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
On 4/1/19 8:53 PM, Sudakshina Das wrote:
>> This could stand to use a comment, a moment's thinking about the sizes, and
>> to
>> use the existing asm output functions.
>>
>> /* PT_NOTE header: namesz, descsz, type.
>> namesz = 4 ("GNU\0")
>> descsz = 12 (see below)
> I was trying out these changes but the descsz of 12 gets rejected by
> readelf. It hits the following
>
>unsigned intsize = is_32bit_elf ? 4 : 8;
>
>printf (_(" Properties: "));
>
>if (pnote->descsz < 8 || (pnote->descsz % size) != 0)
> {
>printf (_("\n"),
> pnote->descsz);
>return;
> }
Hmm, interesting. The docs say that padding is not to be included in descsz
(gabi4.1, page 82). To my eye this is a bug in binutils, but perhaps we will
have to live with it.
Nick, thoughts?
r~
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
Hi Richard
Thanks for the comments and pointing out the much cleaner existing asm
output functions!
On 29/03/2019 17:51, Richard Henderson wrote:
>> +#define ASM_LONG "\t.long\t"
>
> Do not replicate targetm.asm_out.aligned_op.si, or integer_asm_op, really.
>
>> +aarch64_file_end_indicate_exec_stack ()
>> +{
>> + file_end_indicate_exec_stack ();
>> +
>> + if (!aarch64_bti_enabled ()
>> + && aarch64_ra_sign_scope == AARCH64_FUNCTION_NONE)
>> +{
>> + return;
>> +}
>
> This is redundant with...
>
>> +
>> + unsigned feature_1_and = 0;
>> + if (aarch64_bti_enabled ())
>> +feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
>> +
>> + if (aarch64_ra_sign_scope != AARCH64_FUNCTION_NONE)
>> +feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
>> +
>> + if (feature_1_and)
>
> ... this. I prefer the second, as it's obvious.
>
>> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
>> + /* name length. */
>> + fprintf (asm_out_file, ASM_LONG " 1f - 0f\n");
>> + /* data length. */
>> + fprintf (asm_out_file, ASM_LONG " 4f - 1f\n");
>> + /* note type: NT_GNU_PROPERTY_TYPE_0. */
>> + fprintf (asm_out_file, ASM_LONG " 5\n");
>> + fprintf (asm_out_file, "0:\n");
>> + /* vendor name: "GNU". */
>> + fprintf (asm_out_file, STRING_ASM_OP " \"GNU\"\n");
>> + fprintf (asm_out_file, "1:\n");
>> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
>> + /* pr_type: GNU_PROPERTY_AARCH64_FEATURE_1_AND. */
>> + fprintf (asm_out_file, ASM_LONG " 0x%x\n",
>> + GNU_PROPERTY_AARCH64_FEATURE_1_AND);
>> + /* pr_datasz. */\
>> + fprintf (asm_out_file, ASM_LONG " 3f - 2f\n");
>> + fprintf (asm_out_file, "2:\n");
>> + /* GNU_PROPERTY_AARCH64_FEATURE_1_XXX. */
>> + fprintf (asm_out_file, ASM_LONG " 0x%x\n", feature_1_and);
>> + fprintf (asm_out_file, "3:\n");
>> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
>> + fprintf (asm_out_file, "4:\n");
>
> This could stand to use a comment, a moment's thinking about the sizes, and to
> use the existing asm output functions.
>
> /* PT_NOTE header: namesz, descsz, type.
> namesz = 4 ("GNU\0")
> descsz = 12 (see below)
I was trying out these changes but the descsz of 12 gets rejected by
readelf. It hits the following
unsigned intsize = is_32bit_elf ? 4 : 8;
printf (_(" Properties: "));
if (pnote->descsz < 8 || (pnote->descsz % size) != 0)
{
printf (_("\n"),
pnote->descsz);
return;
}
Thanks
Sudi
> type = 5 (NT_GNU_PROPERTY_TYPE_0). */
> assemble_align (POINTER_SIZE);
> assemble_integer (GEN_INT (4), 4, 32, 1);
> assemble_integer (GEN_INT (12), 4, 32, 1);
> assemble_integer (GEN_INT (5), 4, 32, 1);
>
> /* PT_NOTE name */
> assemble_string ("GNU", 4);
>
> /* PT_NOTE contents for NT_GNU_PROPERTY_TYPE_0:
> type = 0xc000 (GNU_PROPERTY_AARCH64_FEATURE_1_AND),
> datasz = 4
> data = feature_1_and
> Note that the current section offset is 16,
> and there has been no padding so far. */
> assemble_integer (GEN_INT (0xc000), 4, 32, 1);
> assemble_integer (GEN_INT (4), 4, 32, 1);
> assemble_integer (GEN_INT (feature_1_and), 4, 32, 1);
>
> /* Pad the size of the note to the required alignment. */
> assemble_align (POINTER_SIZE);
>
>
> r~
>
Re: [PATCH, GCC, AARCH64] Add GNU note section with BTI and PAC.
> +#define ASM_LONG "\t.long\t"
Do not replicate targetm.asm_out.aligned_op.si, or integer_asm_op, really.
> +aarch64_file_end_indicate_exec_stack ()
> +{
> + file_end_indicate_exec_stack ();
> +
> + if (!aarch64_bti_enabled ()
> + && aarch64_ra_sign_scope == AARCH64_FUNCTION_NONE)
> +{
> + return;
> +}
This is redundant with...
> +
> + unsigned feature_1_and = 0;
> + if (aarch64_bti_enabled ())
> +feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
> +
> + if (aarch64_ra_sign_scope != AARCH64_FUNCTION_NONE)
> +feature_1_and |= GNU_PROPERTY_AARCH64_FEATURE_1_PAC;
> +
> + if (feature_1_and)
... this. I prefer the second, as it's obvious.
> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
> + /* name length. */
> + fprintf (asm_out_file, ASM_LONG " 1f - 0f\n");
> + /* data length. */
> + fprintf (asm_out_file, ASM_LONG " 4f - 1f\n");
> + /* note type: NT_GNU_PROPERTY_TYPE_0. */
> + fprintf (asm_out_file, ASM_LONG " 5\n");
> + fprintf (asm_out_file, "0:\n");
> + /* vendor name: "GNU". */
> + fprintf (asm_out_file, STRING_ASM_OP " \"GNU\"\n");
> + fprintf (asm_out_file, "1:\n");
> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
> + /* pr_type: GNU_PROPERTY_AARCH64_FEATURE_1_AND. */
> + fprintf (asm_out_file, ASM_LONG " 0x%x\n",
> +GNU_PROPERTY_AARCH64_FEATURE_1_AND);
> + /* pr_datasz. */\
> + fprintf (asm_out_file, ASM_LONG " 3f - 2f\n");
> + fprintf (asm_out_file, "2:\n");
> + /* GNU_PROPERTY_AARCH64_FEATURE_1_XXX. */
> + fprintf (asm_out_file, ASM_LONG " 0x%x\n", feature_1_and);
> + fprintf (asm_out_file, "3:\n");
> + ASM_OUTPUT_ALIGN (asm_out_file, p2align);
> + fprintf (asm_out_file, "4:\n");
This could stand to use a comment, a moment's thinking about the sizes, and to
use the existing asm output functions.
/* PT_NOTE header: namesz, descsz, type.
namesz = 4 ("GNU\0")
descsz = 12 (see below)
type = 5 (NT_GNU_PROPERTY_TYPE_0). */
assemble_align (POINTER_SIZE);
assemble_integer (GEN_INT (4), 4, 32, 1);
assemble_integer (GEN_INT (12), 4, 32, 1);
assemble_integer (GEN_INT (5), 4, 32, 1);
/* PT_NOTE name */
assemble_string ("GNU", 4);
/* PT_NOTE contents for NT_GNU_PROPERTY_TYPE_0:
type = 0xc000 (GNU_PROPERTY_AARCH64_FEATURE_1_AND),
datasz = 4
data = feature_1_and
Note that the current section offset is 16,
and there has been no padding so far. */
assemble_integer (GEN_INT (0xc000), 4, 32, 1);
assemble_integer (GEN_INT (4), 4, 32, 1);
assemble_integer (GEN_INT (feature_1_and), 4, 32, 1);
/* Pad the size of the note to the required alignment. */
assemble_align (POINTER_SIZE);
r~
