提交 · 1f77f2fc9cace070dbcbe3b1b593c7dea969d858 · openanolis / cloud-kernel

18 3月, 2020 15 次提交

arm64: implement ftrace with regs · 1f77f2fc

由 Torsten Duwe 提交于 2月 08, 2019

commit 3b23e4991fb66f6d152f9055ede271a726ef9f21 upstream

This patch implements FTRACE_WITH_REGS for arm64, which allows a traced
function's arguments (and some other registers) to be captured into a
struct pt_regs, allowing these to be inspected and/or modified. This is
a building block for live-patching, where a function's arguments may be
forwarded to another function. This is also necessary to enable ftrace
and in-kernel pointer authentication at the same time, as it allows the
LR value to be captured and adjusted prior to signing.

Using GCC's -fpatchable-function-entry=N option, we can have the
compiler insert a configurable number of NOPs between the function entry
point and the usual prologue. This also ensures functions are AAPCS
compliant (e.g. disabling inter-procedural register allocation).

For example, with -fpatchable-function-entry=2, GCC 8.1.0 compiles the
following:

| unsigned long bar(void);
|
| unsigned long foo(void)
| {
|         return bar() + 1;
| }

... to:

| <foo>:
|         nop
|         nop
|         stp     x29, x30, [sp, #-16]!
|         mov     x29, sp
|         bl      0 <bar>
|         add     x0, x0, #0x1
|         ldp     x29, x30, [sp], #16
|         ret

This patch builds the kernel with -fpatchable-function-entry=2,
prefixing each function with two NOPs. To trace a function, we replace
these NOPs with a sequence that saves the LR into a GPR, then calls an
ftrace entry assembly function which saves this and other relevant
registers:

| mov	x9, x30
| bl	<ftrace-entry>

Since patchable functions are AAPCS compliant (and the kernel does not
use x18 as a platform register), x9-x18 can be safely clobbered in the
patched sequence and the ftrace entry code.

There are now two ftrace entry functions, ftrace_regs_entry (which saves
all GPRs), and ftrace_entry (which saves the bare minimum). A PLT is
allocated for each within modules.
Signed-off-by: NTorsten Duwe <duwe@suse.de>
[Mark: rework asm, comments, PLTs, initialization, commit message]
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Julien Thierry <jthierry@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

1f77f2fc

arm64: asm-offsets: add S_FP · ecb06c7b

由 Mark Rutland 提交于 10月 18, 2019

commit 1f377e043b3b8ef68caffe47bdad794f4e2cb030 upstream

So that assembly code can more easily manipulate the FP (x29) within a
pt_regs, add an S_FP asm-offsets definition.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

ecb06c7b

arm64: insn: add encoder for MOV (register) · 88892d31

由 Mark Rutland 提交于 10月 18, 2019

commit e3bf8a67f759b498e09999804c3837688e03b304 upstream

For FTRACE_WITH_REGS, we're going to want to generate a MOV (register)
instruction as part of the callsite intialization. As MOV (register) is
an alias for ORR (shifted register), we can generate this with
aarch64_insn_gen_logical_shifted_reg(), but it's somewhat verbose and
difficult to read in-context.

Add a aarch64_insn_gen_move_reg() wrapper for this case so that we can
write callers in a more straightforward way.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

88892d31

arm64: module/ftrace: intialize PLT at load time · 19f2b4ae

由 Mark Rutland 提交于 10月 17, 2019

commit f1a54ae9af0da4d76239256ed640a93ab3aadac0 upstream

Currently we lazily-initialize a module's ftrace PLT at runtime when we
install the first ftrace call. To do so we have to apply a number of
sanity checks, transiently mark the module text as RW, and perform an
IPI as part of handling Neoverse-N1 erratum #1542419.

We only expect the ftrace trampoline to point at ftrace_caller() (AKA
FTRACE_ADDR), so let's simplify all of this by intializing the PLT at
module load time, before the module loader marks the module RO and
performs the intial I-cache maintenance for the module.

Thus we can rely on the module having been correctly intialized, and can
simplify the runtime work necessary to install an ftrace call in a
module. This will also allow for the removal of module_disable_ro().

Tested by forcing ftrace_make_call() to use the module PLT, and then
loading up a module after setting up ftrace with:

| echo ":mod:<module-name>" > set_ftrace_filter;
| echo function > current_tracer;
| modprobe <module-name>

Since FTRACE_ADDR is only defined when CONFIG_DYNAMIC_FTRACE is
selected, we wrap its use along with most of module_init_ftrace_plt()
with ifdeffery rather than using IS_ENABLED().
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

19f2b4ae

arm64: module: rework special section handling · d4199e8c

由 Mark Rutland 提交于 10月 17, 2019

commit bd8b21d3dd661658addc1cd4cc869bab11d28596 upstream

When we load a module, we have to perform some special work for a couple
of named sections. To do this, we iterate over all of the module's
sections, and perform work for each section we recognize.

To make it easier to handle the unexpected absence of a section, and to
make the section-specific logic easer to read, let's factor the section
search into a helper. Similar is already done in the core module loader,
and other architectures (and ideally we'd unify these in future).

If we expect a module to have an ftrace trampoline section, but it
doesn't have one, we'll now reject loading the module. When
ARM64_MODULE_PLTS is selected, any correctly built module should have
one (and this is assumed by arm64's ftrace PLT code) and the absence of
such a section implies something has gone wrong at build time.

Subsequent patches will make use of the new helper.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

d4199e8c

arm64: Makefile: Replace -pg with CC_FLAGS_FTRACE · 007a7aa5

由 Torsten Duwe 提交于 2月 08, 2019

commit edf072d36dbfdf74465b66988f30084b6c996fbf upstream.

In preparation for arm64 supporting ftrace built on other compiler
options, let's have the arm64 Makefiles remove the $(CC_FLAGS_FTRACE)
flags, whatever these may be, rather than assuming '-pg'.

There should be no functional change as a result of this patch.
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

007a7aa5

arm64: ftrace: use GLOBAL() · 9709ac64

由 Mark Rutland 提交于 11月 15, 2018

commit e4fe196642678565766815d99ab98a3a32d72dd4 upstream.

The global exports of ftrace_call and ftrace_graph_call are somewhat
painful to read. Let's use the generic GLOBAL() macro to ameliorate
matters.

There should be no functional change as a result of this patch.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Torsten Duwe <duwe@suse.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: Zou Cao<zoucao@linux.alibaba.com>
Acked-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>

9709ac64

KVM: arm64: Add support for creating PUD hugepages at stage 2 · 497b3882