On 10 March 2016 at 12:43, James Greenhalgh <james.greenha...@arm.com> wrote:
> On Tue, Jan 26, 2016 at 03:43:36PM +0100, Christophe Lyon wrote:
>> With the attachment....
>>
>>
>> On 26 January 2016 at 15:42, Christophe Lyon <christophe.l...@linaro.org>
>> wrote:
>> > Hi,
>> >
>> > This is a followup to PR63304.
>> >
>> > As discussed in bugzilla, this patch disables pcrelative_literal_loads
>> > when -mfix-cortex-a53-843419 (or its default configure option) is
>> > used.
>> >
>> > I copied the behavior of -mfix-cortex-a53-835769 (e.g. in
>> > aarch64_can_inline_p), and I have tested by building the Linux kernel
>> > using -mfix-cortex-a53-843419 and checked that
>> > R_AARCH64_ADR_PREL_PG_HI21 relocations are not emitted anymore (under
>> > CONFIG_ARM64_ERRATUM_843419).
>> >
>> > For reference, this is motivated by:
>> > https://bugs.linaro.org/show_bug.cgi?id=1994
>> > and further details on Launchpad:
>> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1533009
>> >
>> > OK for trunk?
>
> Thanks, this looks like a clear regression from GCC 5 (we can no longer
> build the kernel, so this workaround is fine to go in now). Please remember
> to add the link to the relevant PR in the ChangeLog.
>
> I'd also really appreciate a nice big comment over this code:
>
>> + /* If it is not set on the command line, we default to no pc
>> + relative literal loads, unless the workaround for Cortex-A53
>> + erratum 843419 is in effect. */
>> + if (opts->x_nopcrelative_literal_loads == 2
>> + && !TARGET_FIX_ERR_A53_843419)
>
> Explaining why this is important (i.e. some summary of the discussion
> in PR63304 regarding the kernel module loader).
>
> Can you repost with that comment added? I don't have any other objections
> to the patch.
>
OK, here is an updated version.
> Thanks,
> James
>
>
2016-03-10 Christophe Lyon <christophe.l...@linaro.org>
PR target/70113.
* config/aarch64/aarch64.h (TARGET_FIX_ERR_A53_843419_DEFAULT):
Always define to 0 or 1.
(TARGET_FIX_ERR_A53_843419): New macro.
* config/aarch64/aarch64-elf-raw.h
(TARGET_FIX_ERR_A53_843419_DEFAULT): Update for above changes.
* config/aarch64/aarch64-linux.h: Likewise.
* config/aarch64/aarch64.c
(aarch64_override_options_after_change_1): Do not default
aarch64_nopcrelative_literal_loads to true if Cortex-A53 erratum
843419 is on.
(aarch64_attributes): Handle fix-cortex-a53-843419.
(aarch64_can_inline_p): Likewise.
* config/aarch64/aarch64.opt (aarch64_fix_a53_err843419): Save.
diff --git a/gcc/config/aarch64/aarch64-elf-raw.h
b/gcc/config/aarch64/aarch64-elf-raw.h
index 2dcb6d4..9097017 100644
--- a/gcc/config/aarch64/aarch64-elf-raw.h
+++ b/gcc/config/aarch64/aarch64-elf-raw.h
@@ -35,7 +35,7 @@
" %{mfix-cortex-a53-835769:--fix-cortex-a53-835769}"
#endif
-#ifdef TARGET_FIX_ERR_A53_843419_DEFAULT
+#if TARGET_FIX_ERR_A53_843419_DEFAULT
#define CA53_ERR_843419_SPEC \
" %{!mno-fix-cortex-a53-843419:--fix-cortex-a53-843419}"
#else
diff --git a/gcc/config/aarch64/aarch64-linux.h
b/gcc/config/aarch64/aarch64-linux.h
index 6064b26..5fcaa59 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -53,7 +53,7 @@
" %{mfix-cortex-a53-835769:--fix-cortex-a53-835769}"
#endif
-#ifdef TARGET_FIX_ERR_A53_843419_DEFAULT
+#if TARGET_FIX_ERR_A53_843419_DEFAULT
#define CA53_ERR_843419_SPEC \
" %{!mno-fix-cortex-a53-843419:--fix-cortex-a53-843419}"
#else
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 801f95a..51dfe79 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -8132,9 +8132,18 @@ aarch64_override_options_after_change_1 (struct
gcc_options *opts)
if (opts->x_nopcrelative_literal_loads == 1)
aarch64_nopcrelative_literal_loads = false;
- /* If it is not set on the command line, we default to no
- pc relative literal loads. */
- if (opts->x_nopcrelative_literal_loads == 2)
+ /* If it is not set on the command line, we default to no pc
+ relative literal loads, unless the workaround for Cortex-A53
+ erratum 843419 is in effect. */
+ /* This is PR70113. When building the Linux kernel with
+ CONFIG_ARM64_ERRATUM_843419, support for relocations
+ R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADR_PREL_PG_HI21_NC is
+ removed from the kernel to avoid loading objects with possibly
+ offending sequences. With nopcrelative_literal_loads, we would
+ generate such relocations, preventing the kernel build from
+ succeeding. */
+ if (opts->x_nopcrelative_literal_loads == 2
+ && !TARGET_FIX_ERR_A53_843419)
aarch64_nopcrelative_literal_loads = true;
/* In the tiny memory model it makes no sense
@@ -8818,6 +8827,8 @@ static const struct aarch64_attribute_info
aarch64_attributes[] =
OPT_mgeneral_regs_only },
{ "fix-cortex-a53-835769", aarch64_attr_bool, true, NULL,
OPT_mfix_cortex_a53_835769 },
+ { "fix-cortex-a53-843419", aarch64_attr_bool, true, NULL,
+ OPT_mfix_cortex_a53_843419 },
{ "cmodel", aarch64_attr_enum, false, NULL, OPT_mcmodel_ },
{ "strict-align", aarch64_attr_mask, false, NULL, OPT_mstrict_align },
{ "omit-leaf-frame-pointer", aarch64_attr_bool, true, NULL,
@@ -9232,6 +9243,12 @@ aarch64_can_inline_p (tree caller, tree callee)
2, TARGET_FIX_ERR_A53_835769_DEFAULT))
return false;
+ if (!aarch64_tribools_ok_for_inlining_p (
+ caller_opts->x_aarch64_fix_a53_err843419,
+ callee_opts->x_aarch64_fix_a53_err843419,
+ 2, TARGET_FIX_ERR_A53_843419))
+ return false;
+
/* If the user explicitly specified -momit-leaf-frame-pointer for the
caller and calle and they don't match up, reject inlining. */
if (!aarch64_tribools_ok_for_inlining_p (
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 8b463c9..ec96ce3 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -179,6 +179,20 @@ extern unsigned aarch64_architecture_version;
((aarch64_fix_a53_err835769 == 2) \
? TARGET_FIX_ERR_A53_835769_DEFAULT : aarch64_fix_a53_err835769)
+/* Make sure this is always defined so we don't have to check for ifdefs
+ but rather use normal ifs. */
+#ifndef TARGET_FIX_ERR_A53_843419_DEFAULT
+#define TARGET_FIX_ERR_A53_843419_DEFAULT 0
+#else
+#undef TARGET_FIX_ERR_A53_843419_DEFAULT
+#define TARGET_FIX_ERR_A53_843419_DEFAULT 1
+#endif
+
+/* Apply the workaround for Cortex-A53 erratum 843419. */
+#define TARGET_FIX_ERR_A53_843419 \
+ ((aarch64_fix_a53_err843419 == 2) \
+ ? TARGET_FIX_ERR_A53_843419_DEFAULT : aarch64_fix_a53_err843419)
+
/* ARMv8.1 Adv.SIMD support. */
#define TARGET_SIMD_RDMA (TARGET_SIMD && AARCH64_ISA_RDMA)
diff --git a/gcc/config/aarch64/aarch64.opt b/gcc/config/aarch64/aarch64.opt
index 49ef0c6..c637ff4 100644
--- a/gcc/config/aarch64/aarch64.opt
+++ b/gcc/config/aarch64/aarch64.opt
@@ -73,7 +73,7 @@ Target Report Var(aarch64_fix_a53_err835769) Init(2) Save
Workaround for ARM Cortex-A53 Erratum number 835769.
mfix-cortex-a53-843419
-Target Report
+Target Report Var(aarch64_fix_a53_err843419) Init(2) Save
Workaround for ARM Cortex-A53 Erratum number 843419.
mlittle-endian
