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Change-Id: I126075a330f305c85f8fe1b8c9d408f368be95d1
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commit c5e2edeb01ae9ffbdde95bdcdb6d3614ba1eb195 upstream.
GCC 8.1.0 reports that the ldadd instruction encoding, recently added to
insn.c, doesn't match the mask and couldn't possibly be identified:
linux/arch/arm64/include/asm/insn.h: In function 'aarch64_insn_is_ldadd':
linux/arch/arm64/include/asm/insn.h:280:257: warning: bitwise comparison always evaluates to false [-Wtautological-compare]
Bits [31:30] normally encode the size of the instruction (1 to 8 bytes)
and the current instruction value only encodes the 4- and 8-byte
variants. At the moment only the BPF JIT needs this instruction, and
doesn't require the 1- and 2-byte variants, but to be consistent with
our other ldr and str instruction encodings, clear the size field in the
insn value.
Fixes: 34b8ab091f9ef57a ("bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Change-Id: I914ba0c9ca65af2996d6b67bf45a0d9fabd0ec92
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 34b8ab091f9ef57a2bb3c8c8359a0a03a8abf2f9 upstream.
Since ARMv8.1 supplement introduced LSE atomic instructions back in 2016,
lets add support for STADD and use that in favor of LDXR / STXR loop for
the XADD mapping if available. STADD is encoded as an alias for LDADD with
XZR as the destination register, therefore add LDADD to the instruction
encoder along with STADD as special case and use it in the JIT for CPUs
that advertise LSE atomics in CPUID register. If immediate offset in the
BPF XADD insn is 0, then use dst register directly instead of temporary
one.
Change-Id: I77c90fb42f826fab672db94eddc9e16bbba3a65f
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8968c67a82ab7501bc3b9439c3624a49b42fe54c upstream.
Prefetch-with-intent-to-write is currently part of the XADD mapping in
the AArch64 JIT and follows the kernel's implementation of atomic_add.
This may interfere with other threads executing the LDXR/STXR loop,
leading to potential starvation and fairness issues. Drop the optional
prefetch instruction.
Fixes: 85f68fe89832 ("bpf, arm64: implement jiting of BPF_XADD")
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Change-Id: I3c0f7d2357d668a223991c47402f5004bad70edb
Acked-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Diab Neiroukh <lazerl0rd@thezest.dev>
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Will reported that in BPF_XADD we must use a different register in stxr
instruction for the status flag due to otherwise CONSTRAINED UNPREDICTABLE
behavior per architecture. Reference manual says [1]:
If s == t, then one of the following behaviors must occur:
* The instruction is UNDEFINED.
* The instruction executes as a NOP.
* The instruction performs the store to the specified address, but
the value stored is UNKNOWN.
Thus, use a different temporary register for the status flag to fix it.
Disassembly extract from test 226/STX_XADD_DW from test_bpf.ko:
[...]
0000003c: c85f7d4b ldxr x11, [x10]
00000040: 8b07016b add x11, x11, x7
00000044: c80c7d4b stxr w12, x11, [x10]
00000048: 35ffffac cbnz w12, 0x0000003c
[...]
[1] https://static.docs.arm.com/ddi0487/b/DDI0487B_a_armv8_arm.pdf, p.6132
Fixes: 85f68fe89832 ("bpf, arm64: implement jiting of BPF_XADD")
Reported-by: Will Deacon <will.deacon@arm.com>
Change-Id: I3e7359d7995777097d0488a832b91e6e8cb79e47
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This work implements jiting of BPF_J{LT,LE,SLT,SLE} instructions
with BPF_X/BPF_K variants for the arm64 eBPF JIT.
Change-Id: Ica4714e94e12db24249da7674b125d615a3e8a3b
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This work adds BPF_XADD for BPF_W/BPF_DW to the arm64 JIT and therefore
completes JITing of all BPF instructions, meaning we can thus also remove
the 'notyet' label and do not need to fall back to the interpreter when
BPF_XADD is used in a program!
This now also brings arm64 JIT in line with x86_64, s390x, ppc64, sparc64,
where all current eBPF features are supported.
BPF_W example from test_bpf:
.u.insns_int = {
BPF_ALU32_IMM(BPF_MOV, R0, 0x12),
BPF_ST_MEM(BPF_W, R10, -40, 0x10),
BPF_STX_XADD(BPF_W, R10, R0, -40),
BPF_LDX_MEM(BPF_W, R0, R10, -40),
BPF_EXIT_INSN(),
},
[...]
00000020: 52800247 mov w7, #0x12 // #18
00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40
00000028: d280020a mov x10, #0x10 // #16
0000002c: b82b6b2a str w10, [x25,x11]
// start of xadd mapping:
00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40
00000034: 8b19014a add x10, x10, x25
00000038: f9800151 prfm pstl1strm, [x10]
0000003c: 885f7d4b ldxr w11, [x10]
00000040: 0b07016b add w11, w11, w7
00000044: 880b7d4b stxr w11, w11, [x10]
00000048: 35ffffab cbnz w11, 0x0000003c
// end of xadd mapping:
[...]
BPF_DW example from test_bpf:
.u.insns_int = {
BPF_ALU32_IMM(BPF_MOV, R0, 0x12),
BPF_ST_MEM(BPF_DW, R10, -40, 0x10),
BPF_STX_XADD(BPF_DW, R10, R0, -40),
BPF_LDX_MEM(BPF_DW, R0, R10, -40),
BPF_EXIT_INSN(),
},
[...]
00000020: 52800247 mov w7, #0x12 // #18
00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40
00000028: d280020a mov x10, #0x10 // #16
0000002c: f82b6b2a str x10, [x25,x11]
// start of xadd mapping:
00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40
00000034: 8b19014a add x10, x10, x25
00000038: f9800151 prfm pstl1strm, [x10]
0000003c: c85f7d4b ldxr x11, [x10]
00000040: 8b07016b add x11, x11, x7
00000044: c80b7d4b stxr w11, x11, [x10]
00000048: 35ffffab cbnz w11, 0x0000003c
// end of xadd mapping:
[...]
Tested on Cavium ThunderX ARMv8, test suite results after the patch:
No JIT: [ 3751.855362] test_bpf: Summary: 311 PASSED, 0 FAILED, [0/303 JIT'ed]
With JIT: [ 3573.759527] test_bpf: Summary: 311 PASSED, 0 FAILED, [303/303 JIT'ed]
Change-Id: Id7d92879b2c7b51fd2391bcf706a48ef7894a5f2
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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struct jit_ctx::image is used the store a pointer to the jitted
intructions, which are always little-endian. These instructions
are thus correctly converted from native order to little-endian
before being stored but the pointer 'image' is declared as for
native order values.
Fix this by declaring the field as __le32* instead of u32*.
Same for the pointer used in jit_fill_hole() to initialize
the image.
Change-Id: I5afd33008ee5c035d9b61cf77a4ab4b740ac3240
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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free up BPF_JMP | BPF_CALL | BPF_X opcode to be used by actual
indirect call by register and use kernel internal opcode to
mark call instruction into bpf_tail_call() helper.
Change-Id: I1a45b8e3c13848c9689ce288d4862935ede97fa7
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Remove the dummy bpf_jit_compile() stubs for eBPF JITs and make
that a single __weak function in the core that can be overridden
similarly to the eBPF one. Also remove stale pr_err() mentions
of bpf_jit_compile.
Change-Id: Iac221c09e9ae0879acdd7064d710c4f7cb8f478d
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Split the HAVE_BPF_JIT into two for distinguishing cBPF and eBPF JITs.
Current cBPF ones:
# git grep -n HAVE_CBPF_JIT arch/
arch/arm/Kconfig:44: select HAVE_CBPF_JIT
arch/mips/Kconfig:18: select HAVE_CBPF_JIT if !CPU_MICROMIPS
arch/powerpc/Kconfig:129: select HAVE_CBPF_JIT
arch/sparc/Kconfig:35: select HAVE_CBPF_JIT
Current eBPF ones:
# git grep -n HAVE_EBPF_JIT arch/
arch/arm64/Kconfig:61: select HAVE_EBPF_JIT
arch/s390/Kconfig:126: select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
arch/x86/Kconfig:94: select HAVE_EBPF_JIT if X86_64
Later code also needs this facility to check for eBPF JITs.
Change-Id: Ie7df6f39a8f547e15e9b6d1c56ecc18df8e3ac2e
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change-Id: I8bfc0e53b4bd347adaa298594402a2210aed3b49
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commit 14831fad73f5ac30ac61760487d95a538e6ab3cb upstream.
When running the following command without arm-linux-gnueabi-gcc in
one's $PATH, the following warning is observed:
$ ARCH=arm64 CROSS_COMPILE_COMPAT=arm-linux-gnueabi- make -j72 LLVM=1 mrproper
make[1]: arm-linux-gnueabi-gcc: No such file or directory
This is because KCONFIG is not run for mrproper, so CONFIG_CC_IS_CLANG
is not set, and we end up eagerly evaluating various variables that try
to invoke CC_COMPAT.
This is a similar problem to what was observed in
commit dc960bfeedb0 ("h8300: suppress error messages for 'make clean'")
Reported-by: Lucas Henneman <henneman@google.com>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Change-Id: I672930f558d087230c119ece518b83cac7d8baa7
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20211019223646.1146945-4-ndesaulniers@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 8d75785a814241587802655cc33e384230744f0c ]
Add the 32-bit vdso Makefile to the vdso_install rule so that 'make
vdso_install' installs the 32-bit compat vdso when it is compiled.
Fixes: a7f71a2c8903 ("arm64: compat: Add vDSO")
Change-Id: I554988049d9f4395d226988a410a0a68eeed304d
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20200818014950.42492-1-swboyd@chromium.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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KBUILD_CPPFLAGS is defined differently depending on whether the main
compiler is clang or not. This means that it is not possible to build
the compat vDSO with GCC if the rest of the kernel is built with clang.
Define VDSO_CPPFLAGS directly to break this dependency and allow a clang
kernel to build a compat vDSO with GCC:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- CC=clang \
COMPATCC=arm-linux-gnueabihf-gcc
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: Iaa7f6197bc99ca5c8162c6e34e3dd38c31d894cd
Signed-off-by: Will Deacon <will@kernel.org>
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The jump labels are not used in vdso32 since it is not possible to run
runtime patching on them.
Remove the configuration option from the Makefile.
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: Ie0f311218a761a6b18b3ed3cccf30fd10f440407
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
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* I don't know why this was disabled, but without this config Android 13 hangs on
the splash screen for ages, so let's re-enable it
Change-Id: I13db9b561e13897bc807d8ca3b3ae6a5a5d4a689
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Initial Enery Model was calculated with a device including
less number of available frequencies. This change adds
the missing values, note that all performance values had to be
updated so they would be re-normalized to 0-1024.
Bug: 64837462
Test: YouTube did not have energy regression
Change-Id: I2b4c62d06e39fe0da524af96568187042664d62a
Signed-off-by: Andres Oportus <andresoportus@google.com>
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CPU idle states are mapped into EAS energy model data structures
according to this table:
+ cpu_idle_status
| + idle-cost-data index
| | + meaning
| | | + expected energy cost
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-1 0: CPU active CPU energy > 0
0 1: CPU WFI CPU energy > 0
1 2: CPU off (cluster on) CPU energy = 0
2 3: CPU off (cluster off) CPU energy = 0
Change-Id: I4b51bb74cb96c265731f3872c95947474db973ac
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
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Change-Id: Iad2e3882a2e9d7dbbfd80cf485bbb1f0e664b04f
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
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We need 4 idle-cost-data for CPUs, despite cpu_idle supporting
only 3 different idle states. The idle-cost-data property length
should always be one more entry longer than the number of available
cpu_idle states. The idle-cost-data property has to have the same
length for both CLUSTER_COST_N and CPU_COST_N.
Bug: 37641804
Change-Id: Ic14a6a1ef4409e81c5adc23575f7d1157d6eadce
Signed-off-by: Siqi Lin <siqilin@google.com>
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Squash of commits:
ed6442938f08: Enable EAS in 8998 MTP
3989a0e22e44: Update Energy Model using Muskie
922c6f4b9e8b: Added idle-cost-data to energy model and fixed
busy-cost-data for big cluster cpus
Change-Id: I717eb88204f5e28a1afd494dc484895cc749e2fc
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Android passes a lot of arguments via kernel command line.
Current kernel command line is close to limit on a lot of devices.
Increase kernel command line size to avoid cases when arguments
are trimmed.
Bug: 120817253
Change-Id: I18fc3a066273718fce021d85ca31e3f755706a13
Signed-off-by: Syuan Yang <syuanyang@google.com>
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emulation_proc_handler() changes table->data for proc_dointvec_minmax
and can generate the following Oops if called concurrently with itself:
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
| Internal error: Oops: 96000006 [#1] SMP
| Call trace:
| update_insn_emulation_mode+0xc0/0x148
| emulation_proc_handler+0x64/0xb8
| proc_sys_call_handler+0x9c/0xf8
| proc_sys_write+0x18/0x20
| __vfs_write+0x20/0x48
| vfs_write+0xe4/0x1d0
| ksys_write+0x70/0xf8
| __arm64_sys_write+0x20/0x28
| el0_svc_common.constprop.0+0x7c/0x1c0
| el0_svc_handler+0x2c/0xa0
| el0_svc+0x8/0x200
To fix this issue, keep the table->data as &insn->current_mode and
use container_of() to retrieve the insn pointer. Another mutex is
used to protect against the current_mode update but not for retrieving
insn_emulation as table->data is no longer changing.
Bug: 237540956
Co-developed-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: Haibin Zhang <haibinzhang@tencent.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220128090324.2727688-1-hewenliang4@huawei.com
Link: https://lore.kernel.org/r/9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com
Signed-off-by: Will Deacon <will@kernel.org>
[Lee: Added Fixes: tag]
(cherry picked from commit af483947d472eccb79e42059276c4deed76f99a6
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core)
Fixes: 587064b610c7 ("arm64: Add framework for legacy instruction emulation")
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: If9b96bb79c79903f9d8292e719b06fdef57ef1c5
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Change-Id: Id4056255732a1865e4b97a443ba936a51954e407
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[ Upstream commit aa69fb62bea15126e744af2e02acc0d6cf3ed4da ]
After r363059 and r363928 in LLVM, a build using ld.lld as the linker
with CONFIG_RANDOMIZE_BASE enabled fails like so:
ld.lld: error: relocation R_AARCH64_ABS32 cannot be used against symbol
__efistub_stext_offset; recompile with -fPIC
Fangrui and Peter figured out that ld.lld is incorrectly considering
__efistub_stext_offset as a relative symbol because of the order in
which symbols are evaluated. _text is treated as an absolute symbol
and stext is a relative symbol, making __efistub_stext_offset a
relative symbol.
Adding ABSOLUTE will force ld.lld to evalute this expression in the
right context and does not change ld.bfd's behavior. ld.lld will
need to be fixed but the developers do not see a quick or simple fix
without some research (see the linked issue for further explanation).
Add this simple workaround so that ld.lld can continue to link kernels.
Link: https://github.com/ClangBuiltLinux/linux/issues/561
Link: https://github.com/llvm/llvm-project/commit/025a815d75d2356f2944136269aa5874721ec236
Link: https://github.com/llvm/llvm-project/commit/249fde85832c33f8b06c6b4ac65d1c4b96d23b83
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Debugged-by: Fangrui Song <maskray@google.com>
Debugged-by: Peter Smith <peter.smith@linaro.org>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
[will: add comment]
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Change-Id: Iffdd3234d04eab4f470ef9008bd8d92b5d658093
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Commit e19a6ee2460b ("arm64: kernel: Save and restore UAO and
addr_limit on exception entry") states that exception handler inherits
the original PSTATE.UAO value, so UAO needes to be reset
explicitly. However, ARM 8.2 Extension documentation says:
PSTATE.UAO is copied to SPSR_ELx.UAO and is then set to 0 on an
exception taken from AArch64 to AArch64
so hardware already does the right thing.
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: I2c20b1082d7e096d089097946829550040778c2b
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commit 3b92fa7485eba16b05166fddf38ab42f2ff6ab95 upstream.
With CONFIG_EXPERT=y, CONFIG_KASAN=y, CONFIG_RANDOMIZE_BASE=n,
CONFIG_RELOCATABLE=n, we observe the following failure when trying to
link the kernel image with LD=ld.lld:
error: section: .exit.data is not contiguous with other relro sections
ld.lld defaults to -z relro while ld.bfd defaults to -z norelro. This
was previously fixed, but only for CONFIG_RELOCATABLE=y.
Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201016175339.2429280-1-ndesaulniers@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: Idf6fa5186e771d62b969c371ae4b1b8d4bc154ea
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commit 3bbd3db86470c701091fb1d67f1fab6621debf50 upstream.
readelf complains about the section layout of vmlinux when building
with CONFIG_RELOCATABLE=y (for KASLR):
readelf: Warning: [21]: Link field (0) should index a symtab section.
readelf: Warning: [21]: Info field (0) should index a relocatable section.
Also, it seems that our use of '-pie -shared' is contradictory, and
thus ambiguous. In general, the way KASLR is wired up at the moment
is highly tailored to how ld.bfd happens to implement (and conflate)
PIE executables and shared libraries, so given the current effort to
support other toolchains, let's fix some of these issues as well.
- Drop the -pie linker argument and just leave -shared. In ld.bfd,
the differences between them are unclear (except for the ELF type
of the produced image [0]) but lld chokes on seeing both at the
same time.
- Rename the .rela output section to .rela.dyn, as is customary for
shared libraries and PIE executables, so that it is not misidentified
by readelf as a static relocation section (producing the warnings
above).
- Pass the -z notext and -z norelro options to explicitly instruct the
linker to permit text relocations, and to omit the RELRO program
header (which requires a certain section layout that we don't adhere
to in the kernel). These are the defaults for current versions of
ld.bfd.
- Discard .eh_frame and .gnu.hash sections to avoid them from being
emitted between .head.text and .text, screwing up the section layout.
These changes only affect the ELF image, and produce the same binary
image.
[0] b9dce7f1ba01 ("arm64: kernel: force ET_DYN ELF type for ...")
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Smith <peter.smith@linaro.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I9fe6c4b09993a97051ea856a5053b220f2722872
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binutils 2.27
[ Upstream commit fd9dde6abcb9bfe6c6bee48834e157999f113971 ]
Upon upgrading to binutils 2.27, we found that our lz4 and gzip
compressed kernel images were significantly larger, resulting is 10ms
boot time regressions.
As noted by Rahul:
"aarch64 binaries uses RELA relocations, where each relocation entry
includes an addend value. This is similar to x86_64. On x86_64, the
addend values are also stored at the relocation offset for relative
relocations. This is an optimization: in the case where code does not
need to be relocated, the loader can simply skip processing relative
relocations. In binutils-2.25, both bfd and gold linkers did this for
x86_64, but only the gold linker did this for aarch64. The kernel build
here is using the bfd linker, which stored zeroes at the relocation
offsets for relative relocations. Since a set of zeroes compresses
better than a set of non-zero addend values, this behavior was resulting
in much better lz4 compression.
The bfd linker in binutils-2.27 is now storing the actual addend values
at the relocation offsets. The behavior is now consistent with what it
does for x86_64 and what gold linker does for both architectures. The
change happened in this upstream commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=1f56df9d0d5ad89806c24e71f296576d82344613
Since a bunch of zeroes got replaced by non-zero addend values, we see
the side effect of lz4 compressed image being a bit bigger.
To get the old behavior from the bfd linker, "--no-apply-dynamic-relocs"
flag can be used:
$ LDFLAGS="--no-apply-dynamic-relocs" make
With this flag, the compressed image size is back to what it was with
binutils-2.25.
If the kernel is using ASLR, there aren't additional runtime costs to
--no-apply-dynamic-relocs, as the relocations will need to be applied
again anyway after the kernel is relocated to a random address.
If the kernel is not using ASLR, then presumably the current default
behavior of the linker is better. Since the static linker performed the
dynamic relocs, and the kernel is not moved to a different address at
load time, it can skip applying the relocations all over again."
Some measurements:
$ ld -v
GNU ld (binutils-2.25-f3d35cf6) 2.25.51.20141117
^
$ ls -l vmlinux
-rwxr-x--- 1 ndesaulniers eng 300652760 Oct 26 11:57 vmlinux
$ ls -l Image.lz4-dtb
-rw-r----- 1 ndesaulniers eng 16932627 Oct 26 11:57 Image.lz4-dtb
$ ld -v
GNU ld (binutils-2.27-53dd00a1) 2.27.0.20170315
^
pre patch:
$ ls -l vmlinux
-rwxr-x--- 1 ndesaulniers eng 300376208 Oct 26 11:43 vmlinux
$ ls -l Image.lz4-dtb
-rw-r----- 1 ndesaulniers eng 18159474 Oct 26 11:43 Image.lz4-dtb
post patch:
$ ls -l vmlinux
-rwxr-x--- 1 ndesaulniers eng 300376208 Oct 26 12:06 vmlinux
$ ls -l Image.lz4-dtb
-rw-r----- 1 ndesaulniers eng 16932466 Oct 26 12:06 Image.lz4-dtb
By Siqi's measurement w/ gzip:
binutils 2.27 with this patch (with --no-apply-dynamic-relocs):
Image 41535488
Image.gz 13404067
binutils 2.27 without this patch (without --no-apply-dynamic-relocs):
Image 41535488
Image.gz 14125516
Any compression scheme should be able to get better results from the
longer runs of zeros, not just GZIP and LZ4.
10ms boot time savings isn't anything to get excited about, but users of
arm64+compression+bfd-2.27 should not have to pay a penalty for no
runtime improvement.
Reported-by: Gopinath Elanchezhian <gelanchezhian@google.com>
Reported-by: Sindhuri Pentyala <spentyala@google.com>
Reported-by: Wei Wang <wvw@google.com>
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Suggested-by: Rahul Chaudhry <rahulchaudhry@google.com>
Suggested-by: Siqi Lin <siqilin@google.com>
Suggested-by: Stephen Hines <srhines@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[will: added comment to Makefile]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I3c48704174bb1b32dcd24e32b5d30cfbd8d576e7
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GNU ld used to set the ELF file type to ET_DYN for PIE executables, which
is the same file type used for shared libraries. However, this was changed
recently, and now PIE executables are emitted as ET_EXEC instead.
The distinction is only relevant for ELF loaders, and so there is little
reason to care about the difference when building the kernel, which is
why the change has gone unnoticed until now.
However, debuggers do use the ELF binary, and expect ET_EXEC type files
to appear in memory at the exact offset described in the ELF metadata.
This means source level debugging is no longer possible when KASLR is in
effect or when executing the stub.
So add the -shared LD option when building with CONFIG_RELOCATABLE=y. This
forces the ELF file type to be set to ET_DYN (which is what you get when
building with binutils 2.24 and earlier anyway), and has no other ill
effects.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: Ic2de8f7219566c8da4485b7d300e10a1860d97e9
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Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
in particular. So, probe for whether it's available and use the previous
(linux) targets if it isn't.
Reported-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: Icf5462a8318b347cf11559c1654886c48c7a62b5
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With the recent syntax extension, Kconfig is now able to evaluate the
compiler / toolchain capability.
However, accumulating flags to 'LD' is not compatible with the way
it works; 'LD' must be passed to Kconfig to call $(ld-option,...)
from Kconfig files. If you tweak 'LD' in arch Makefile depending on
CONFIG_CPU_BIG_ENDIAN, this would end up with circular dependency
between Makefile and Kconfig.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: I8a7654684975d45e979917e3b1c4b6249dec02ec
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The make rpm target depends on proper UTS_MACHINE definition. Also, use
the variable in arch/arm64/kernel/setup.c, so that it's not accidentally
removed in the future.
Reported-and-tested-by: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: Icaa52a4062ef79ab74f4c18fc503bb795e0fb415
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arch/arm64/lib/mem*.S
commit ec9d78070de986ecf581ea204fd322af4d2477ec upstream.
Commit 39d114ddc682 ("arm64: add KASAN support") added .weak directives to
arch/arm64/lib/mem*.S instead of changing the existing SYM_FUNC_START_PI
macros. This can lead to the assembly snippet `.weak memcpy ... .globl
memcpy` which will produce a STB_WEAK memcpy with GNU as but STB_GLOBAL
memcpy with LLVM's integrated assembler before LLVM 12. LLVM 12 (since
https://reviews.llvm.org/D90108) will error on such an overridden symbol
binding.
Use the appropriate SYM_FUNC_START_WEAK_PI instead.
Fixes: 39d114ddc682 ("arm64: add KASAN support")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201029181951.1866093-1-maskray@google.com
Signed-off-by: Will Deacon <will@kernel.org>
[nd: backport to adjust for missing:
commit 3ac0f4526dfb ("arm64: lib: Use modern annotations for assembly functions")
commit 35e61c77ef38 ("arm64: asm: Add new-style position independent function annotations")]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Change-Id: Ibebbfa15f3337b5a2ac88ba683c5e429758d7a98
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Most crypto drivers involving kernel mode NEON take care to put the code
that actually touches the NEON register file in a separate compilation
unit, to prevent the compiler from reordering code that preserves or
restores the NEON context with code that may corrupt it. This is
necessary because we currently have no way to express the restrictions
imposed upon use of the NEON in kernel mode in a way that the compiler
understands.
However, in the case of aes-ce-cipher, it did not seem unreasonable to
deviate from this rule, given how it does not seem possible for the
compiler to reorder cross object function calls with asm blocks whose
in- and output constraints reflect that it reads from and writes to
memory.
Now that LTO is being proposed for the arm64 kernel, it is time to
revisit this. The link time optimization may replace the function
calls to kernel_neon_begin() and kernel_neon_end() with instantiations
of the IR that make up its implementation, allowing further reordering
with the asm block.
So let's clean this up, and move the asm() blocks into a separate .S
file.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-By: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[ DD3Boh : Backported to 4.4 ]
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
Change-Id: I3a857137556143229e9b6d670e5c77e3cdafffde
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The asm/opcodes.h file is now gone, but probes.h still references it
for not obvious reason. Removing the #include directive fixes
the compilation.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: I707437533cf368b173dc280750132ad4e283ea92
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decode-insn code has to be reused by arm64 uprobe implementation as well.
Therefore, this patch protects some portion of kprobe code and renames few
other, so that decode-insn functionality can be reused by uprobe even when
CONFIG_KPROBES is not defined.
kprobe_opcode_t and struct arch_specific_insn are also defined by
linux/kprobes.h, when CONFIG_KPROBES is not defined. So, protect these
definitions in asm/probes.h.
linux/kprobes.h already includes asm/kprobes.h. Therefore, remove inclusion
of asm/kprobes.h from decode-insn.c.
There are some definitions like kprobe_insn and kprobes_handler_t etc can
be re-used by uprobe. So, it would be better to remove 'k' from their
names.
struct arch_specific_insn is specific to kprobe. Therefore, introduce a new
struct arch_probe_insn which will be common for both kprobe and uprobe, so
that decode-insn code can be shared. Modify kprobe code accordingly.
Function arm_probe_decode_insn() will be needed by uprobe as well. So make
it global.
Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: I27db6fac61414eaa415db9cbf94bc5a8adc9f7b6
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[ Upstream commit c9a4ef66450145a356a626c833d3d7b1668b3ded ]
In assembly, many instances of __emit_inst(x) expand to a directive. In
a few places __emit_inst(x) is used as an assembler macro argument. For
example, in arch/arm64/kvm/hyp/entry.S
ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
expands to the following by the C preprocessor:
alternative_insn nop, .inst (0xd500401f | ((0) << 16 | (4) << 5) | ((!!1) << 8)), 4, 1
Both comma and space are separators, with an exception that content
inside a pair of parentheses/quotes is not split, so the clang
integrated assembler splits the arguments to:
nop, .inst, (0xd500401f | ((0) << 16 | (4) << 5) | ((!!1) << 8)), 4, 1
GNU as preprocesses the input with do_scrub_chars(). Its arm64 backend
(along with many other non-x86 backends) sees:
alternative_insn nop,.inst(0xd500401f|((0)<<16|(4)<<5)|((!!1)<<8)),4,1
# .inst(...) is parsed as one argument
while its x86 backend sees:
alternative_insn nop,.inst (0xd500401f|((0)<<16|(4)<<5)|((!!1)<<8)),4,1
# The extra space before '(' makes the whole .inst (...) parsed as two arguments
The non-x86 backend's behavior is considered unintentional
(https://sourceware.org/bugzilla/show_bug.cgi?id=25750).
So drop the space separator inside `.inst (...)` to make the clang
integrated assembler work.
Suggested-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/939
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Change-Id: I6644ce237fcfe594fb6147f5d3df9359dc192581
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The opcodes.h drags in a lot of definition from the 32bit port, most
of which is not required at all. Clean things up a bit by moving
the bare minimum of what is required next to the actual users,
and drop the include file.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Change-Id: Idc1568eaf85077c03d22bd8e070474dfe271a7d8
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[ Upstream commit 33309ecda0070506c49182530abe7728850ebe78 ]
The dcache_by_line_op macro suffers from a couple of small problems:
First, the GAS directives that are currently being used rely on
assembler behavior that is not documented, and probably not guaranteed
to produce the correct behavior going forward. As a result, we end up
with some undefined symbols in cache.o:
$ nm arch/arm64/mm/cache.o
...
U civac
...
U cvac
U cvap
U cvau
This is due to the fact that the comparisons used to select the
operation type in the dcache_by_line_op macro are comparing symbols
not strings, and even though it seems that GAS is doing the right
thing here (undefined symbols by the same name are equal to each
other), it seems unwise to rely on this.
Second, when patching in a DC CVAP instruction on CPUs that support it,
the fallback path consists of a DC CVAU instruction which may be
affected by CPU errata that require ARM64_WORKAROUND_CLEAN_CACHE.
Solve these issues by unrolling the various maintenance routines and
using the conditional directives that are documented as operating on
strings. To avoid the complexity of nested alternatives, we move the
DC CVAP patching to __clean_dcache_area_pop, falling back to a branch
to __clean_dcache_area_poc if DCPOP is not supported by the CPU.
Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ DD3Boh: Backported to 4.4, ignoring __clean_dcache_area_pop function ]
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
Signed-off-by: Bruno Martins <bgcngm@gmail.com>
Change-Id: I006dd10a0f3706b9302832d04c65262861239709
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commit ed6ed11830a9ded520db31a6e2b69b6b0a1eb0e2 upstream.
Replace the literal load of the addend vector with a sequence that
performs each add individually. This sequence is only 2 instructions
longer than the original, and 2% faster on Cortex-A53.
This is an improvement by itself, but also works around a Clang issue,
whose integrated assembler does not implement the GNU ARM asm syntax
completely, and does not support the =literal notation for FP registers
(more info at https://bugs.llvm.org/show_bug.cgi?id=38642)
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: Ic8f7adcd28bd2da57b465a8e11e9d55b5669a539
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LLVM's integrated assembler appears to assume an argument with default
value is passed whenever it sees a comma right after the macro name.
It will be fine if the number of following arguments is one less than
the number of parameters specified in the macro definition. Otherwise,
it fails. For example, the following code works:
$ cat foo.s
.macro foo arg1=2, arg2=4
ldr r0, [r1, #\arg1]
ldr r0, [r1, #\arg2]
.endm
foo, arg2=8
$ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
arm-linux-gnueabihf-objdump -dr ias.o
ias.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <.text>:
0: e5910001 ldr r0, [r1, #2]
4: e5910003 ldr r0, [r1, #8]
While the the following code would fail:
$ cat foo.s
.macro foo arg1=2, arg2=4
ldr r0, [r1, #\arg1]
ldr r0, [r1, #\arg2]
.endm
foo, arg1=2, arg2=8
$ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
foo.s:6:14: error: too many positional arguments
foo, arg1=2, arg2=8
This causes build failures as follows:
arch/arm64/kernel/vdso/gettimeofday.S:230:24: error: too many positional
arguments
clock_gettime_return, shift=1
^
arch/arm64/kernel/vdso/gettimeofday.S:253:24: error: too many positional
arguments
clock_gettime_return, shift=1
^
arch/arm64/kernel/vdso/gettimeofday.S:274:24: error: too many positional
arguments
clock_gettime_return, shift=1
This error is not in mainline because commit 28b1a824a4f4 ("arm64: vdso:
Substitute gettimeofday() with C implementation") rewrote this assembler
file in C as part of a 25 patch series that is unsuitable for stable.
Just remove the comma in the clock_gettime_return invocations in 4.19 so
that GNU as and LLVM's integrated assembler work the same.
Link:
https://github.com/ClangBuiltLinux/linux/issues/1349
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jian Cai <jiancai@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I7eea04241c1f8ac7bc3b7915b781acdd1e2b6686
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Several function prototypes for the set/get functions defined by
module_param_call() have a slightly wrong argument types. This fixes
those in an effort to clean up the calls when running under type-enforced
compiler instrumentation for CFI. This is the result of running the
following semantic patch:
@match_module_param_call_function@
declarer name module_param_call;
identifier _name, _set_func, _get_func;
expression _arg, _mode;
@@
module_param_call(_name, _set_func, _get_func, _arg, _mode);
@fix_set_prototype
depends on match_module_param_call_function@
identifier match_module_param_call_function._set_func;
identifier _val, _param;
type _val_type, _param_type;
@@
int _set_func(
-_val_type _val
+const char * _val
,
-_param_type _param
+const struct kernel_param * _param
) { ... }
@fix_get_prototype
depends on match_module_param_call_function@
identifier match_module_param_call_function._get_func;
identifier _val, _param;
type _val_type, _param_type;
@@
int _get_func(
-_val_type _val
+char * _val
,
-_param_type _param
+const struct kernel_param * _param
) { ... }
Two additional by-hand changes are included for places where the above
Coccinelle script didn't notice them:
drivers/platform/x86/thinkpad_acpi.c
fs/lockd/svc.c
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Bug: 67506682
Change-Id: I2c9c0ee8ed28065e63270a52c155e5e7d2791295
(cherry picked from commit e4dca7b7aa08b22893c45485d222b5807c1375ae)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
(cherry picked from commit 24da2c84bd7dcdf2b56fa8d3b2f833656ee60a01)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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All current versions of GNU gold crash when linking kernel modules
with ARM64_MODULE_PLTS due to a known bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=14592
To work around the problem, this change removes NOLOAD from .plt
and .init.plt.
Bug: 62093296
Bug: 67506682
Change-Id: Ie59c15dc2e60859361b5c7dac5a515eabf8bb005
(am from https://patchwork.kernel.org/patch/10085781/)
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
(cherry picked from commit 331f1f5c7b05132e71232e33eba32b57d1683afc)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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Some versions of GNU gold are known to produce broken code with
--fix-cortex-a53-843419 as explained in this bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=21491
If ARM64_ERRATUM_843419 is disabled and we're using GNU gold, pass
--no-fix-cortex-a53-843419 to the linker to ensure the erratum
fix is not used even if the linker is configured to enable it by
default.
This change also adds a warning if the erratum fix is enabled and
gold version <1.14 is used.
Bug: 62093296
Bug: 67506682
Change-Id: I5669fa920292adc0fd973035f27dafd4a76d919a
(am from https://patchwork.kernel.org/patch/10085777/)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
(cherry picked from commit 5c41c483accd942c053cc232148d7eb557f5a049)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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enabled
Cortex-A53 erratum 843419 is worked around by the linker, although it is
a configure-time option to GCC as to whether ld is actually asked to
apply the workaround or not.
This patch ensures that we pass --fix-cortex-a53-843419 to the linker
when both CONFIG_ARM64_ERRATUM_843419=y and the linker supports the
option.
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: Ic94f6218117a3d52c792ddbec0bff1b5d293c34f
(cherry picked from commit 6ffe9923f2350c19b95a2c9ebf1b4f5f275986f2)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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Make sure the linker doesn't remove .altinstructions or
.altinstr_replacement when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is
enabled.
Bug: 62093296
Bug: 67506682
Change-Id: I73f8a96679083909ec6865ee87519163ac7dcbe3
(am from https://patchwork.kernel.org/patch/10085799/)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
(cherry picked from commit e611641232f79677a0aa0f34c51c179655b57222)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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Make thin archives build the default, but keep the config option
to allow exemptions if any breakage can't be quickly solved.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
(cherry picked from commit 799c43415442414b1032580c47684cb709dfed6d)
Change-Id: I8df3f9aa5eca69e192612bdae10abcb70a9d6176
Signed-off-by: Dan Aloni <daloni@magicleap.com>
(cherry picked from commit 1bc68cb00d9d8e2cb0bcedb35dc6c06406292d6e)
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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Introduce LD_DEAD_CODE_DATA_ELIMINATION option for architectures to
select to build with -ffunction-sections, -fdata-sections, and link
with --gc-sections. It requires some work (documented) to ensure all
unreferenced entrypoints are live, and requires toolchain and build
verification, so it is made a per-arch option for now.
On a random powerpc64le build, this yelds a significant size saving,
it boots and runs fine, but there is a lot I haven't tested as yet, so
these savings may be reduced if there are bugs in the link.
text data bss dec filename
11169741 1180744 1923176 14273661 vmlinux
10445269 1004127 1919707 13369103 vmlinux.dce
~700K text, ~170K data, 6% removed from kernel image size.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
(cherry-pick from b67067f1176df6ee727450546b58704e4b588563)
Change-Id: I81b63489605bc2f146498d0bb0e1cc5b7adab8a0
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>
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