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arm64 fixes for -rc5

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- Fix extension/truncation of return values from 32-bit system calls
 
 - Fix interaction between unwinding and tracing
 
 - Fix spurious toolchain warning emitted during make
 
 - Fix Kconfig help text for RANDOMIZE_MODULE_REGION_FULL
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "It's all pretty minor but the main fix is sorting out how we deal with
  return values from 32-bit system calls as audit expects error codes to
  be sign-extended to 64 bits

  Summary:

   - Fix extension/truncation of return values from 32-bit system calls

   - Fix interaction between unwinding and tracing

   - Fix spurious toolchain warning emitted during make

   - Fix Kconfig help text for RANDOMIZE_MODULE_REGION_FULL"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: stacktrace: avoid tracing arch_stack_walk()
  arm64: stacktrace: fix comment
  arm64: fix the doc of RANDOMIZE_MODULE_REGION_FULL
  arm64: move warning about toolchains to archprepare
  arm64: fix compat syscall return truncation
This commit is contained in:
Linus Torvalds 2021-08-06 11:33:49 -07:00
commit 73f25536f2
10 changed files with 51 additions and 34 deletions
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9
arch/arm64/Kconfig
View file

@ -1800,11 +1800,11 @@ config RANDOMIZE_BASE
If unsure, say N.
config RANDOMIZE_MODULE_REGION_FULL
bool "Randomize the module region over a 4 GB range"
bool "Randomize the module region over a 2 GB range"
depends on RANDOMIZE_BASE
default y
help
Randomizes the location of the module region inside a 4 GB window
Randomizes the location of the module region inside a 2 GB window
covering the core kernel. This way, it is less likely for modules
to leak information about the location of core kernel data structures
but it does imply that function calls between modules and the core
@ -1812,7 +1812,10 @@ config RANDOMIZE_MODULE_REGION_FULL
When this option is not set, the module region will be randomized over
a limited range that contains the [_stext, _etext] interval of the
core kernel, so branch relocations are always in range.
core kernel, so branch relocations are almost always in range unless
ARM64_MODULE_PLTS is enabled and the region is exhausted. In this
particular case of region exhaustion, modules might be able to fall
back to a larger 2GB area.
config CC_HAVE_STACKPROTECTOR_SYSREG
def_bool $(cc-option,-mstack-protector-guard=sysreg -mstack-protector-guard-reg=sp_el0 -mstack-protector-guard-offset=0)

21
arch/arm64/Makefile
View file

@ -21,19 +21,11 @@ LDFLAGS_vmlinux += -shared -Bsymbolic -z notext \
endif
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
$(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
else
ifeq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
LDFLAGS_vmlinux += --fix-cortex-a53-843419
endif
endif
ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS), y)
ifneq ($(CONFIG_ARM64_LSE_ATOMICS), y)
$(warning LSE atomics not supported by binutils)
endif
endif
cc_has_k_constraint := $(call try-run,echo \
'int main(void) { \
asm volatile("and w0, w0, %w0" :: "K" (4294967295)); \
@ -176,6 +168,17 @@ vdso_install:
archprepare:
$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
@echo "warning: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum" >&2
endif
endif
ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS),y)
ifneq ($(CONFIG_ARM64_LSE_ATOMICS),y)
@echo "warning: LSE atomics not supported by binutils" >&2
endif
endif
# We use MRPROPER_FILES and CLEAN_FILES now
archclean:

12
arch/arm64/include/asm/ptrace.h
View file

@ -320,7 +320,17 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
static inline unsigned long regs_return_value(struct pt_regs *regs)
{
return regs->regs[0];
unsigned long val = regs->regs[0];
/*
* Audit currently uses regs_return_value() instead of
* syscall_get_return_value(). Apply the same sign-extension here until
* audit is updated to use syscall_get_return_value().
*/
if (compat_user_mode(regs))
val = sign_extend64(val, 31);
return val;
}
static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)

2
arch/arm64/include/asm/stacktrace.h
View file

@ -35,7 +35,7 @@ struct stack_info {
* accounting information necessary for robust unwinding.
*
* @fp: The fp value in the frame record (or the real fp)
* @pc: The fp value in the frame record (or the real lr)
* @pc: The lr value in the frame record (or the real lr)
*
* @stacks_done: Stacks which have been entirely unwound, for which it is no
* longer valid to unwind to.

21
arch/arm64/include/asm/syscall.h
View file

@ -29,24 +29,25 @@ static inline void syscall_rollback(struct task_struct *task,
regs->regs[0] = regs->orig_x0;
}
static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
unsigned long val = regs->regs[0];
if (is_compat_thread(task_thread_info(task)))
val = sign_extend64(val, 31);
return val;
}
static inline long syscall_get_error(struct task_struct *task,
struct pt_regs *regs)
{
unsigned long error = regs->regs[0];
if (is_compat_thread(task_thread_info(task)))
error = sign_extend64(error, 31);
unsigned long error = syscall_get_return_value(task, regs);
return IS_ERR_VALUE(error) ? error : 0;
}
static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
return regs->regs[0];
}
static inline void syscall_set_return_value(struct task_struct *task,
struct pt_regs *regs,
int error, long val)

4
arch/arm64/kernel/kaslr.c
View file

@ -162,7 +162,9 @@ u64 __init kaslr_early_init(void)
* a PAGE_SIZE multiple in the range [_etext - MODULES_VSIZE,
* _stext) . This guarantees that the resulting region still
* covers [_stext, _etext], and that all relative branches can
* be resolved without veneers.
* be resolved without veneers unless this region is exhausted
* and we fall back to a larger 2GB window in module_alloc()
* when ARM64_MODULE_PLTS is enabled.
*/
module_range = MODULES_VSIZE - (u64)(_etext - _stext);
module_alloc_base = (u64)_etext + offset - MODULES_VSIZE;

2
arch/arm64/kernel/ptrace.c
View file

@ -1862,7 +1862,7 @@ void syscall_trace_exit(struct pt_regs *regs)
audit_syscall_exit(regs);
if (flags & _TIF_SYSCALL_TRACEPOINT)
trace_sys_exit(regs, regs_return_value(regs));
trace_sys_exit(regs, syscall_get_return_value(current, regs));
if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);

3
arch/arm64/kernel/signal.c
View file

@ -29,6 +29,7 @@
#include <asm/unistd.h>
#include <asm/fpsimd.h>
#include <asm/ptrace.h>
#include <asm/syscall.h>
#include <asm/signal32.h>
#include <asm/traps.h>
#include <asm/vdso.h>
@ -890,7 +891,7 @@ static void do_signal(struct pt_regs *regs)
retval == -ERESTART_RESTARTBLOCK ||
(retval == -ERESTARTSYS &&
!(ksig.ka.sa.sa_flags & SA_RESTART)))) {
regs->regs[0] = -EINTR;
syscall_set_return_value(current, regs, -EINTR, 0);
regs->pc = continue_addr;
}

2
arch/arm64/kernel/stacktrace.c
View file

@ -218,7 +218,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
#ifdef CONFIG_STACKTRACE
noinline void arch_stack_walk(stack_trace_consume_fn consume_entry,
noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task,
struct pt_regs *regs)
{

9
arch/arm64/kernel/syscall.c
View file

@ -54,10 +54,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
ret = do_ni_syscall(regs, scno);
}
if (is_compat_task())
ret = lower_32_bits(ret);
regs->regs[0] = ret;
syscall_set_return_value(current, regs, 0, ret);
/*
* Ultimately, this value will get limited by KSTACK_OFFSET_MAX(),
@ -115,7 +112,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
* syscall. do_notify_resume() will send a signal to userspace
* before the syscall is restarted.
*/
regs->regs[0] = -ERESTARTNOINTR;
syscall_set_return_value(current, regs, -ERESTARTNOINTR, 0);
return;
}
@ -136,7 +133,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
* anyway.
*/
if (scno == NO_SYSCALL)
regs->regs[0] = -ENOSYS;
syscall_set_return_value(current, regs, -ENOSYS, 0);
scno = syscall_trace_enter(regs);
if (scno == NO_SYSCALL)
goto trace_exit;