mirror of
https://github.com/torvalds/linux
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cd24f44050
csr_sscratch CSR holds current task_struct address when hart is in user space. Trap handler on entry spills csr_sscratch into "tp" (x2) register and zeroes out csr_sscratch CSR. Trap handler on exit reloads "tp" with expected user mode value and place current task_struct address again in csr_sscratch CSR. This patch assumes "tp" is pointing to task_struct. If value in csr_sscratch is numerically greater than "tp" then it assumes csr_sscratch is correct address of current task_struct. This logic holds when - hart is in user space, "tp" will be less than csr_sscratch. - hart is in kernel space but not in trap handler, "tp" will be more than csr_sscratch (csr_sscratch being equal to 0). - hart is executing trap handler - "tp" is still pointing to user mode but csr_sscratch contains ptr to task_struct. Thus numerically higher. - "tp" is pointing to task_struct but csr_sscratch now contains either 0 or numerically smaller value (transiently holds user mode tp) Link: https://lkml.kernel.org/r/20231026233837.612405-1-debug@rivosinc.com Signed-off-by: Deepak Gupta <debug@rivosinc.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> Tested-by: Hsieh-Tseng Shen <woodrow.shen@sifive.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Glenn Washburn <development@efficientek.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Jeff Xie <xiehuan09@gmail.com> Cc: Kieran Bingham <kbingham@kernel.org> Cc: Palmer Dabbelt <palmer@rivosinc.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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atomic | ||
basic | ||
clang-tools | ||
coccinelle | ||
dtc | ||
dummy-tools | ||
gcc-plugins | ||
gdb | ||
genksyms | ||
kconfig | ||
ksymoops | ||
mod | ||
package | ||
selinux | ||
tracing | ||
.gitignore | ||
as-version.sh | ||
asn1_compiler.c | ||
bloat-o-meter | ||
bootgraph.pl | ||
bpf_doc.py | ||
cc-can-link.sh | ||
cc-version.sh | ||
check-git | ||
check-sysctl-docs | ||
check_extable.sh | ||
checkdeclares.pl | ||
checkincludes.pl | ||
checkkconfigsymbols.py | ||
checkpatch.pl | ||
checkstack.pl | ||
checksyscalls.sh | ||
checkversion.pl | ||
cleanfile | ||
cleanpatch | ||
coccicheck | ||
config | ||
const_structs.checkpatch | ||
decode_stacktrace.sh | ||
decodecode | ||
depmod.sh | ||
dev-needs.sh | ||
diffconfig | ||
documentation-file-ref-check | ||
export_report.pl | ||
extract-ikconfig | ||
extract-module-sig.pl | ||
extract-sys-certs.pl | ||
extract-vmlinux | ||
extract_xc3028.pl | ||
faddr2line | ||
file-size.sh | ||
find-unused-docs.sh | ||
gcc-x86_32-has-stack-protector.sh | ||
gcc-x86_64-has-stack-protector.sh | ||
gen-randstruct-seed.sh | ||
generate_initcall_order.pl | ||
generate_rust_analyzer.py | ||
generate_rust_target.rs | ||
get_abi.pl | ||
get_dvb_firmware | ||
get_feat.pl | ||
get_maintainer.pl | ||
gfp-translate | ||
head-object-list.txt | ||
headerdep.pl | ||
headers_install.sh | ||
insert-sys-cert.c | ||
install.sh | ||
jobserver-exec | ||
kallsyms.c | ||
Kbuild.include | ||
Kconfig.include | ||
kernel-doc | ||
ld-version.sh | ||
leaking_addresses.pl | ||
Lindent | ||
link-vmlinux.sh | ||
Makefile | ||
Makefile.asm-generic | ||
Makefile.build | ||
Makefile.clang | ||
Makefile.clean | ||
Makefile.compiler | ||
Makefile.debug | ||
Makefile.defconf | ||
Makefile.dtbinst | ||
Makefile.extrawarn | ||
Makefile.gcc-plugins | ||
Makefile.headersinst | ||
Makefile.host | ||
Makefile.kasan | ||
Makefile.kcov | ||
Makefile.kcsan | ||
Makefile.kmsan | ||
Makefile.lib | ||
Makefile.modfinal | ||
Makefile.modinst | ||
Makefile.modpost | ||
Makefile.package | ||
Makefile.randstruct | ||
Makefile.ubsan | ||
Makefile.userprogs | ||
Makefile.vmlinux | ||
Makefile.vmlinux_o | ||
makelst | ||
markup_oops.pl | ||
min-tool-version.sh | ||
misc-check | ||
mkcompile_h | ||
mksysmap | ||
mkuboot.sh | ||
module.lds.S | ||
modules-check.sh | ||
nsdeps | ||
objdiff | ||
objdump-func | ||
orc_hash.sh | ||
pahole-flags.sh | ||
pahole-version.sh | ||
parse-maintainers.pl | ||
patch-kernel | ||
profile2linkerlist.pl | ||
prune-kernel | ||
recordmcount.c | ||
recordmcount.h | ||
recordmcount.pl | ||
relocs_check.sh | ||
remove-stale-files | ||
rust_is_available.sh | ||
rust_is_available_bindgen_libclang.h | ||
rust_is_available_test.py | ||
rustdoc_test_builder.rs | ||
rustdoc_test_gen.rs | ||
setlocalversion | ||
show_delta | ||
sign-file.c | ||
sorttable.c | ||
sorttable.h | ||
spdxcheck-test.sh | ||
spdxcheck.py | ||
spdxexclude | ||
spelling.txt | ||
sphinx-pre-install | ||
split-man.pl | ||
stackdelta | ||
stackusage | ||
subarch.include | ||
syscallhdr.sh | ||
syscallnr.sh | ||
syscalltbl.sh | ||
tags.sh | ||
test_fortify.sh | ||
tools-support-relr.sh | ||
unifdef.c | ||
ver_linux | ||
xen-hypercalls.sh | ||
xz_wrap.sh |