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[PATCH binutils 1/4] aarch64: add STO_AARCH64_VARIANT_PCS and DT_AARCH64_VARIANT_PCS
- From: Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>
- To: Binutils <binutils at sourceware dot org>
- Cc: nd <nd at arm dot com>
- Date: Thu, 23 May 2019 11:07:23 +0000
- Subject: [PATCH binutils 1/4] aarch64: add STO_AARCH64_VARIANT_PCS and DT_AARCH64_VARIANT_PCS
- References: <72a65558-263b-bb35-5fbb-7d9d5dce1717@arm.com>
The bottom 2 bits of st_other are used for visibility, the top 6 bits are
de facto reserved for processor specific use. This patch defines a
bits to mark function symbols that follow a variant procedure call standard
with different register usage convention.
A dynamic tag is also defined that marks modules with R_<CLS>_JUMP_SLOT
relocations referencing symbols marked with STO_AARCH64_VARIANT_PCS.
This can be used by dynamic linkers that support lazy binding to decide
what registers need to be preserved during symbol resolution.
binutils/ChangeLog:
2019-05-22 Szabolcs Nagy <szabolcs.nagy@arm.com>
* readelf.c (get_aarch64_dynamic_type): Handle DT_AARCH64_VARIANT_PCS.
(get_aarch64_symbol_other): New, handles STO_AARCH64_VARIANT_PCS.
(get_symbol_other): Call get_aarch64_symbol_other.
include/ChangeLog:
2019-05-22 Szabolcs Nagy <szabolcs.nagy@arm.com>
* elf/aarch64.h (DT_AARCH64_VARIANT_PCS): Define.
(STO_AARCH64_VARIANT_PCS): Define.
diff --git a/binutils/readelf.c b/binutils/readelf.c
index c31a5c1266..0e8b27bcfe 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -1804,6 +1804,7 @@ get_aarch64_dynamic_type (unsigned long type)
{
case DT_AARCH64_BTI_PLT: return "AARCH64_BTI_PLT";
case DT_AARCH64_PAC_PLT: return "AARCH64_PAC_PLT";
+ case DT_AARCH64_VARIANT_PCS: return "AARCH64_VARIANT_PCS";
default:
return NULL;
}
@@ -11095,6 +11096,22 @@ get_solaris_symbol_visibility (unsigned int visibility)
}
}
+static const char *
+get_aarch64_symbol_other (unsigned int other)
+{
+ static char buf[32];
+
+ if (other & STO_AARCH64_VARIANT_PCS)
+ {
+ other &= ~STO_AARCH64_VARIANT_PCS;
+ if (other == 0)
+ return "VARIANT_PCS";
+ snprintf (buf, sizeof buf, "VARIANT_PCS | %x", other);
+ return buf;
+ }
+ return NULL;
+}
+
static const char *
get_mips_symbol_other (unsigned int other)
{
@@ -11206,6 +11223,9 @@ get_symbol_other (Filedata * filedata, unsigned int other)
switch (filedata->file_header.e_machine)
{
+ case EM_AARCH64:
+ result = get_aarch64_symbol_other (other);
+ break;
case EM_MIPS:
result = get_mips_symbol_other (other);
break;
diff --git a/include/elf/aarch64.h b/include/elf/aarch64.h
index 4466547626..721378abf8 100644
--- a/include/elf/aarch64.h
+++ b/include/elf/aarch64.h
@@ -38,6 +38,11 @@
/* Processor specific dynamic array tags. */
#define DT_AARCH64_BTI_PLT (DT_LOPROC + 1)
#define DT_AARCH64_PAC_PLT (DT_LOPROC + 3)
+#define DT_AARCH64_VARIANT_PCS (DT_LOPROC + 5)
+
+/* AArch64-specific values for st_other. */
+#define STO_AARCH64_VARIANT_PCS 0x80 /* Symbol may follow different call
+ convention from the base PCS. */
/* Relocation types. */