linux.git/arch/riscv/kernel/vdso, branch v6.5

riscv: replace deprecated scall with ecall

2023-06-20T16:02:09+00:00

scall is a deprecated alias for ecall. ecall is used in several places,
so there is no assembler compatibility concern.

Signed-off-by: Fangrui Song 
Link: https://lore.kernel.org/r/20230423223210.126948-1-maskray@google.com
Signed-off-by: Palmer Dabbelt

Merge tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2023-04-28T23:55:39+00:00

Pull RISC-V updates from Palmer Dabbelt:

 - Support for runtime detection of the Svnapot extension

 - Support for Zicboz when clearing pages

 - We've moved to GENERIC_ENTRY

 - Support for !MMU on rv32 systems

 - The linear region is now mapped via huge pages

 - Support for building relocatable kernels

 - Support for the hwprobe interface

 - Various fixes and cleanups throughout the tree

* tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (57 commits)
  RISC-V: hwprobe: Explicity check for -1 in vdso init
  RISC-V: hwprobe: There can only be one first
  riscv: Allow to downgrade paging mode from the command line
  dt-bindings: riscv: add sv57 mmu-type
  RISC-V: hwprobe: Remove __init on probe_vendor_features()
  riscv: Use --emit-relocs in order to move .rela.dyn in init
  riscv: Check relocations at compile time
  powerpc: Move script to check relocations at compile time in scripts/
  riscv: Introduce CONFIG_RELOCATABLE
  riscv: Move .rela.dyn outside of init to avoid empty relocations
  riscv: Prepare EFI header for relocatable kernels
  riscv: Unconditionnally select KASAN_VMALLOC if KASAN
  riscv: Fix ptdump when KASAN is enabled
  riscv: Fix EFI stub usage of KASAN instrumented strcmp function
  riscv: Move DTB_EARLY_BASE_VA to the kernel address space
  riscv: Rework kasan population functions
  riscv: Split early and final KASAN population functions
  riscv: Use PUD/P4D/PGD pages for the linear mapping
  riscv: Move the linear mapping creation in its own function
  riscv: Get rid of riscv_pfn_base variable
  ...

RISC-V: Add hwprobe vDSO function and data

2023-04-18T22:48:18+00:00

Add a vDSO function __vdso_riscv_hwprobe, which can sit in front of the
riscv_hwprobe syscall and answer common queries. We stash a copy of
static answers for the "all CPUs" case in the vDSO data page. This data
is private to the vDSO, so we can decide later to change what's stored
there or under what conditions we defer to the syscall. Currently all
data can be discovered at boot, so the vDSO function answers all queries
when the cpumask is set to the "all CPUs" hint.

There's also a boolean in the data that lets the vDSO function know that
all CPUs are the same. In that case, the vDSO will also answer queries
for arbitrary CPU masks in addition to the "all CPUs" hint.

Signed-off-by: Evan Green 
Link: https://lore.kernel.org/r/20230407231103.2622178-7-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt

vdso: Improve cmd_vdso_check to check all dynamic relocations

2023-03-21T20:15:34+00:00

The actual intention is that no dynamic relocation exists in the VDSO. For
this the VDSO build validates that the resulting .so file does not have any
relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture,
which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside
of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative
relocations too.

However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If
a port fails to determine the exact .rel[a].dyn size, the trailing zeros
become R_*_NONE relocations. E.g. ld's powerpc port recently fixed
https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are
generally a no-op in the dynamic loaders. So just ignore them.

Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting
.so file does not contain any R_* relocation entries except R_*_NONE.

Signed-off-by: Fangrui Song 
Signed-off-by: Thomas Gleixner 
Tested-by: Vincenzo Frascino  # for aarch64
Reviewed-by: Christophe Leroy 
Reviewed-by: Vincenzo Frascino  # for vDSO, aarch64
Acked-by: Michael Ellerman  (powerpc)
Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com

riscv: alternative: patch alternatives in the vDSO

2023-02-01T07:29:42+00:00

Make it possible to use alternatives in the vDSO, so that better
implementations can be used if possible.

Signed-off-by: Jisheng Zhang 
Reviewed-by: Guo Ren 
Reviewed-by: Andrew Jones 
Link: https://lore.kernel.org/r/20230128172856.3814-11-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt

riscv: vdso: fix section overlapping under some conditions

2022-11-30T02:45:53+00:00

lkp reported a build error, I tried the config and can reproduce
build error as below:

  VDSOLD  arch/riscv/kernel/vdso/vdso.so.dbg
ld.lld: error: section .note file range overlaps with .text
>>> .note range is [0x7C8, 0x803]
>>> .text range is [0x800, 0x1993]

ld.lld: error: section .text file range overlaps with .dynamic
>>> .text range is [0x800, 0x1993]
>>> .dynamic range is [0x808, 0x937]

ld.lld: error: section .note virtual address range overlaps with .text
>>> .note range is [0x7C8, 0x803]
>>> .text range is [0x800, 0x1993]

Fix it by setting DISABLE_BRANCH_PROFILING which will disable branch
tracing for vdso, thus avoid useless _ftrace_annotated_branch section
and _ftrace_branch section. Although we can also fix it by removing
the hardcoded .text begin address, but I think that's another story
and should be put into another patch.

Link: https://lore.kernel.org/lkml/202210122123.Cc4FPShJ-lkp@intel.com/#r
Reported-by: kernel test robot 
Signed-off-by: Jisheng Zhang 
Link: https://lore.kernel.org/r/20221102170254.1925-1-jszhang@kernel.org
Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt

RISC-V: vdso: Do not add missing symbols to version section in linker script

2022-11-10T23:06:14+00:00

Recently, ld.lld moved from '--undefined-version' to
'--no-undefined-version' as the default, which breaks the compat vDSO
build:

  ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_gettimeofday' failed: symbol not defined
  ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_gettime' failed: symbol not defined
  ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_getres' failed: symbol not defined

These symbols are not present in the compat vDSO or the regular vDSO for
32-bit but they are unconditionally included in the version section of
the linker script, which is prohibited with '--no-undefined-version'.

Fix this issue by only including the symbols that are actually exported
in the version section of the linker script.

Link: https://github.com/ClangBuiltLinux/linux/issues/1756
Signed-off-by: Nathan Chancellor 
Tested-by: Conor Dooley 
Link: https://lore.kernel.org/r/20221108171324.3377226-1-nathan@kernel.org/
Signed-off-by: Palmer Dabbelt

riscv: vdso: fix build with llvm

2022-11-10T21:58:36+00:00

Even after commit 89fd4a1df829 ("riscv: jump_label: mark arguments as
const to satisfy asm constraints"), building with CC_OPTIMIZE_FOR_SIZE
+ LLVM=1 can reproduce below build error:

  CC      arch/riscv/kernel/vdso/vgettimeofday.o
In file included from :4:
In file included from lib/vdso/gettimeofday.c:5:
In file included from include/vdso/datapage.h:17:
In file included from include/vdso/processor.h:10:
In file included from arch/riscv/include/asm/vdso/processor.h:7:
In file included from include/linux/jump_label.h:112:
arch/riscv/include/asm/jump_label.h:42:3: error:
invalid operand for inline asm constraint 'i'
                "       .option push                            \n\t"
                ^
1 error generated.

I think the problem is when "-Os" is passed as CFLAGS, it's removed by
"CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os" which is
introduced in commit e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday
broke dynamic ftrace"), thus no optimization at all for vgettimeofday.c
arm64 does remove "-Os" as well, but it forces "-O2" after removing
"-Os".

I compared the generated vgettimeofday.o with "-O2" and "-Os",
I think no big performance difference. So let's tell the kbuild not
to remove "-Os" rather than follow arm64 style.

vdso related performance can be improved a lot when building kernel with
CC_OPTIMIZE_FOR_SIZE after this commit, ("-Os" VS no optimization)

Fixes: e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace")
Signed-off-by: Jisheng Zhang 
Tested-by: Conor Dooley 
Link: https://lore.kernel.org/r/20221031182943.2453-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt

riscv: compat: vdso: Add COMPAT_VDSO base code implementation

2022-04-26T20:36:53+00:00

There is no vgettimeofday supported in rv32 that makes simple to
generate rv32 vdso code which only needs riscv64 compiler. Other
architectures need change compiler or -m (machine parameter) to
support vdso32 compiling. If rv32 support vgettimeofday (which
cause C compile) in future, we would add CROSS_COMPILE to support
that makes more requirement on compiler enviornment.

linux-rv64/arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg:
file format elf64-littleriscv

Disassembly of section .text:

0000000000000800 <__vdso_rt_sigreturn>:
 800:   08b00893                li      a7,139
 804:   00000073                ecall
 808:   0000                    unimp
        ...

000000000000080c <__vdso_getcpu>:
 80c:   0a800893                li      a7,168
 810:   00000073                ecall
 814:   8082                    ret
        ...

0000000000000818 <__vdso_flush_icache>:
 818:   10300893                li      a7,259
 81c:   00000073                ecall
 820:   8082                    ret

linux-rv32/arch/riscv/kernel/vdso/vdso.so.dbg:
file format elf32-littleriscv

Disassembly of section .text:

00000800 <__vdso_rt_sigreturn>:
 800:   08b00893                li      a7,139
 804:   00000073                ecall
 808:   0000                    unimp
        ...

0000080c <__vdso_getcpu>:
 80c:   0a800893                li      a7,168
 810:   00000073                ecall
 814:   8082                    ret
        ...

00000818 <__vdso_flush_icache>:
 818:   10300893                li      a7,259
 81c:   00000073                ecall
 820:   8082                    ret

Finally, reuse all *.S from vdso in compat_vdso that makes
implementation clear and readable.

Signed-off-by: Guo Ren 
Signed-off-by: Guo Ren 
Tested-by: Heiko Stuebner 
Link: https://lore.kernel.org/r/20220405071314.3225832-17-guoren@kernel.org
Signed-off-by: Palmer Dabbelt

riscv/vdso: Add support for time namespaces

2021-10-04T21:16:43+00:00

Implement generic vdso time namespace support which also enables time
namespaces for riscv. This is quite similar to what arm64 does.

selftest/timens test result:
  1..10
  ok 1 Passed for CLOCK_BOOTTIME (syscall)
  ok 2 Passed for CLOCK_BOOTTIME (vdso)
  ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
  ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
  ok 5 Passed for CLOCK_MONOTONIC (syscall)
  ok 6 Passed for CLOCK_MONOTONIC (vdso)
  ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall)
  ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso)
  ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall)
  ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso)
  # Totals: pass:8 fail:0 xfail:0 xpass:0 skip:2 error:0

Signed-off-by: Tong Tiangen 
Signed-off-by: Palmer Dabbelt