Commit 4a39ac5b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random 

Pull random number generator updates from Jason Donenfeld:
 "Originally I'd planned on sending each of the vDSO getrandom()
  architecture ports to their respective arch trees. But as we started
  to work on this, we found lots of interesting issues in the shared
  code and infrastructure, the fixes for which the various archs needed
  to base their work.

  So in the end, this turned into a nice collaborative effort fixing up
  issues and porting to 5 new architectures -- arm64, powerpc64,
  powerpc32, s390x, and loongarch64 -- with everybody pitching in and
  commenting on each other's code. It was a fun development cycle.

  This contains:

   - Numerous fixups to the vDSO selftest infrastructure, getting it
     running successfully on more platforms, and fixing bugs in it.

   - Additions to the vDSO getrandom & chacha selftests. Basically every
     time manual review unearthed a bug in a revision of an arch patch,
     or an ambiguity, the tests were augmented.

     By the time the last arch was submitted for review, s390x, v1 of
     the series was essentially fine right out of the gate.

   - Fixes to the the generic C implementation of vDSO getrandom, to
     build and run successfully on all archs, decoupling it from
     assumptions we had (unintentionally) made on x86_64 that didn't
     carry through to the other architectures.

   - Port of vDSO getrandom to LoongArch64, from Xi Ruoyao and acked by
     Huacai Chen.

   - Port of vDSO getrandom to ARM64, from Adhemerval Zanella and acked
     by Will Deacon.

   - Port of vDSO getrandom to PowerPC, in both 32-bit and 64-bit
     varieties, from Christophe Leroy and acked by Michael Ellerman.

   - Port of vDSO getrandom to S390X from Heiko Carstens, the arch
     maintainer.

  While it'd be natural for there to be things to fix up over the course
  of the development cycle, these patches got a decent amount of review
  from a fairly diverse crew of folks on the mailing lists, and, for the
  most part, they've been cooking in linux-next, which has been helpful
  for ironing out build issues.

  In terms of architectures, I think that mostly takes care of the
  important 64-bit archs with hardware still being produced and running
  production loads in settings where vDSO getrandom is likely to help.

  Arguably there's still RISC-V left, and we'll see for 6.13 whether
  they find it useful and submit a port"

* tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (47 commits)
  selftests: vDSO: check cpu caps before running chacha test
  s390/vdso: Wire up getrandom() vdso implementation
  s390/vdso: Move vdso symbol handling to separate header file
  s390/vdso: Allow alternatives in vdso code
  s390/module: Provide find_section() helper
  s390/facility: Let test_facility() generate static branch if possible
  s390/alternatives: Remove ALT_FACILITY_EARLY
  s390/facility: Disable compile time optimization for decompressor code
  selftests: vDSO: fix vdso_config for s390
  selftests: vDSO: fix ELF hash table entry size for s390x
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32
  powerpc/vdso: Refactor CFLAGS for CVDSO build
  powerpc/vdso32: Add crtsavres
  mm: Define VM_DROPPABLE for powerpc/32
  powerpc/vdso: Fix VDSO data access when running in a non-root time namespace
  selftests: vDSO: don't include generated headers for chacha test
  arm64: vDSO: Wire up getrandom() vDSO implementation
  arm64: alternative: make alternative_has_cap_likely() VDSO compatible
  selftests: vDSO: also test counter in vdso_test_chacha
  ...
parents c8d8a35d 210860e7

Documentation/ABI/stable/vdso

+5 −3
Original line number Diff line number Diff line
@@ -9,9 +9,11 @@ maps an ELF DSO into that program's address space. This DSO is called 
the vDSO and it often contains useful and highly-optimized alternatives

to real syscalls.



These functions are called just like ordinary C function according to

your platform's ABI.  Call them from a sensible context.  (For example,

if you set CS on x86 to something strange, the vDSO functions are

These functions are called according to your platform's ABI. On many

platforms they are called just like ordinary C function. On other platforms

(ex: powerpc) they are called with the same convention as system calls which

is different from ordinary C functions. Call them from a sensible context.

(For example, if you set CS on x86 to something strange, the vDSO functions are

within their rights to crash.)  In addition, if you pass a bad

pointer to a vDSO function, you might get SIGSEGV instead of -EFAULT.

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -263,6 +263,7 @@ config ARM64 
	select TRACE_IRQFLAGS_NMI_SUPPORT

	select HAVE_SOFTIRQ_ON_OWN_STACK

	select USER_STACKTRACE_SUPPORT

	select VDSO_GETRANDOM

	help

	  ARM 64-bit (AArch64) Linux support.

arch/arm64/include/asm/alternative-macros.h

+4 −0
Original line number Diff line number Diff line
@@ -230,7 +230,11 @@ alternative_has_cap_likely(const unsigned long cpucap) 
		return false;



	asm goto(

#ifdef BUILD_VDSO

	ALTERNATIVE("b	%l[l_no]", "nop", %[cpucap])

#else

	ALTERNATIVE_CB("b	%l[l_no]", %[cpucap], alt_cb_patch_nops)

#endif

	:

	: [cpucap] "i" (cpucap)

	:

arch/arm64/include/asm/mman.h

+5 −1
Original line number Diff line number Diff line
@@ -2,9 +2,11 @@ 
#ifndef __ASM_MMAN_H__

#define __ASM_MMAN_H__



#include <uapi/asm/mman.h>



#ifndef BUILD_VDSO

#include <linux/compiler.h>

#include <linux/types.h>

#include <uapi/asm/mman.h>



static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,

	unsigned long pkey)
@@ -68,4 +70,6 @@ static inline bool arch_validate_flags(unsigned long vm_flags) 
}

#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)



#endif /* !BUILD_VDSO */



#endif /* ! __ASM_MMAN_H__ */

arch/arm64/include/asm/vdso/getrandom.h

0 → 100644
+50 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#ifndef __ASM_VDSO_GETRANDOM_H

#define __ASM_VDSO_GETRANDOM_H



#ifndef __ASSEMBLY__



#include <asm/unistd.h>

#include <asm/vdso/vsyscall.h>

#include <vdso/datapage.h>



/**

 * getrandom_syscall - Invoke the getrandom() syscall.

 * @buffer:	Destination buffer to fill with random bytes.

 * @len:	Size of @buffer in bytes.

 * @flags:	Zero or more GRND_* flags.

 * Returns:	The number of random bytes written to @buffer, or a negative value indicating an error.

 */

static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)

{

	register void *buffer asm ("x0") = _buffer;

	register size_t len asm ("x1") = _len;

	register unsigned int flags asm ("x2") = _flags;

	register long ret asm ("x0");

	register long nr asm ("x8") = __NR_getrandom;



	asm volatile(

	"       svc #0\n"

	: "=r" (ret)

	: "r" (buffer), "r" (len), "r" (flags), "r" (nr)

	: "memory");



	return ret;

}



static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)

{

	/*

	 * The RNG data is in the real VVAR data page, but if a task belongs to a time namespace

	 * then VVAR_DATA_PAGE_OFFSET points to the namespace-specific VVAR page and VVAR_TIMENS_

	 * PAGE_OFFSET points to the real VVAR page.

	 */

	if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)

		return (void *)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * (1UL << CONFIG_PAGE_SHIFT);

	return &_vdso_rng_data;

}



#endif /* !__ASSEMBLY__ */



#endif /* __ASM_VDSO_GETRANDOM_H */