From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 840c054fd0efb048df6fceb0c46385ec5b66dfe6 ]
The syscall ABI includes the gcc functional calling ABI since a syscall
implies userland caller and kernel callee.
The current gcc ABI (v3) for ARCv2 ISA required 64-bit data be passed in
even-odd register pairs, (potentially punching reg holes when passing such
values as args). This was partly driven by the fact that the double-word
LDD/STD instructions in ARCv2 expect the register alignment and thus gcc
forcing this avoids extra MOV at the cost of a few unused register (which we
have plenty anyways).
This however was rejected as part of upstreaming gcc port to HS. So the new
ABI v4 doesn't enforce the even-odd reg restriction.
Do note that for ARCompact ISA builds v3 and v4 are practically the same in
terms of gcc code generation.
In terms of change management, we infer the new ABI if gcc 6.x onwards
is used for building the kernel.
This also needs a stable backport to enable older kernels to work with
new tools/user-space
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
arch/arc/include/uapi/asm/elf.h | 11 +++++++++--
arch/arc/kernel/process.c | 2 +-
arch/arc/kernel/setup.c | 6 ++++--
3 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/arc/include/uapi/asm/elf.h b/arch/arc/include/uapi/asm/elf.h
index 0f99ac8..0037a58 100644
--- a/arch/arc/include/uapi/asm/elf.h
+++ b/arch/arc/include/uapi/asm/elf.h
@@ -13,8 +13,15 @@
/* Machine specific ELF Hdr flags */
#define EF_ARC_OSABI_MSK 0x00000f00
-#define EF_ARC_OSABI_ORIG 0x00000000 /* MUST be zero for back-compat */
-#define EF_ARC_OSABI_CURRENT 0x00000300 /* v3 (no legacy syscalls) */
+
+#define EF_ARC_OSABI_V3 0x00000300 /* v3 (no legacy syscalls) */
+#define EF_ARC_OSABI_V4 0x00000400 /* v4 (64bit data any reg align) */
+
+#if __GNUC__ < 6
+#define EF_ARC_OSABI_CURRENT EF_ARC_OSABI_V3
+#else
+#define EF_ARC_OSABI_CURRENT EF_ARC_OSABI_V4
+#endif
typedef unsigned long elf_greg_t;
typedef unsigned long elf_fpregset_t;
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index fdd8971..f45b987 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -223,7 +223,7 @@ int elf_check_arch(const struct elf32_hdr *x)
return 0;
eflags = x->e_flags;
- if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) {
+ if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
pr_err("ABI mismatch - you need newer toolchain\n");
force_sigsegv(SIGSEGV, current);
return 0;
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 252bf60..e5ec478 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -234,8 +234,10 @@ static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
cpu->dccm.base_addr, TO_KB(cpu->dccm.sz),
cpu->iccm.base_addr, TO_KB(cpu->iccm.sz));
- n += scnprintf(buf + n, len - n,
- "OS ABI [v3]\t: no-legacy-syscalls\n");
+ n += scnprintf(buf + n, len - n, "OS ABI [v%d]\t: %s\n",
+ EF_ARC_OSABI_CURRENT >> 8,
+ EF_ARC_OSABI_CURRENT == EF_ARC_OSABI_V3 ?
+ "no-legacy-syscalls" : "64-bit data any register aligned");
return buf;
}
--
2.7.4
--
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