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putty-source/unix/uxutils.c

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Check for auxv.h and hwcap.h before including them. uClibc-ng does not provide <sys/auxv.h>, and a non-Linux-kernel-based Unixlike system running on Arm will probably not provide <asm/hwcap.h>. Now we check for both of those headers at autoconf time, and if either one is absent, we don't do the runtime test for Arm crypto acceleration. This should only make a difference on systems where this module previously failed to compile at all. But obviously it would be nicer to find alternative ways to check for crypto acceleration on such systems; patches welcome.
2019-03-26 18:40:51 +00:00
#include "putty.h"
Support hardware AES on Arm platforms. The refactored sshaes.c gives me a convenient slot to drop in a second hardware-accelerated AES implementation, similar to the existing one but using Arm NEON intrinsics in place of the x86 AES-NI ones. This needed a minor structural change, because Arm systems are often heterogeneous, containing more than one type of CPU which won't necessarily all support the same set of architecture features. So you can't test at run time for the presence of AES acceleration by querying the CPU you're running on - even if you found a way to do it, the answer wouldn't be reliable once the OS started migrating your process between CPUs. Instead, you have to ask the OS itself, because only that knows about _all_ the CPUs on the system. So that means the aes_hw_available() mechanism has to extend a tentacle into each platform subdirectory. The trickiest part was the nest of ifdefs that tries to detect whether the compiler can support the necessary parts. I had successful test-compiles on several compilers, and was able to run the code directly on an AArch64 tablet (so I know it passes cryptsuite), but it's likely that at least some Arm platforms won't be able to build it because of some path through the ifdefs that I haven't been able to test yet.
2019-01-16 22:08:45 +00:00
#include "ssh.h"
uxutils.c: move some definitions into a header file. If the autoconf/ifdef system ends up taking the trivial branch through all the Arm-architecture ifdefs, then we define the always-fail version of getauxval as a 'static inline' function, and then (because none of our desired HWCAP_FOO values is defined at all) never call it. This leads to a compiler warning because we defined a static function and never called it - i.e. at the default -Werror, a build failure. Of course it's perfectly sensible to define a static inline function that never gets called! Header files do it all the time, and nobody is expected to ensure that if they include a header file then they take care to refer to every static inline function it defines. But if the definition is in the _source_ file rather than a header file, then clang (in particular on macOS) will give a warning. So the easy solution is to move the inline definitions of getauxval into a header file, which suppresses the warning without requiring me to faff about with further ifdefs to make the definitions conditional on at least one use.
2020-12-24 09:34:13 +00:00
#include "uxutils.h"
Support FreeBSD's API for querying the ELF aux vector. We use this for detecting the Arm crypto extension and using it to enable accelerated AES and/or SHA-{1,2}. Previously, I had code that called glibc's getauxval(3) function, conditioned on #ifdef __linux__. Now, instead, I do an autoconf test to query the presence of getauxval itself (so that any other system with the same API can still work), and alongside it, also check for the analogous FreeBSD libc function elf_aux_info(3). As a result, building on Arm FreeBSD now gets the accelerated-crypto autodetection.
2020-10-09 18:14:57 +00:00
uxutils.c: move some definitions into a header file. If the autoconf/ifdef system ends up taking the trivial branch through all the Arm-architecture ifdefs, then we define the always-fail version of getauxval as a 'static inline' function, and then (because none of our desired HWCAP_FOO values is defined at all) never call it. This leads to a compiler warning because we defined a static function and never called it - i.e. at the default -Werror, a build failure. Of course it's perfectly sensible to define a static inline function that never gets called! Header files do it all the time, and nobody is expected to ensure that if they include a header file then they take care to refer to every static inline function it defines. But if the definition is in the _source_ file rather than a header file, then clang (in particular on macOS) will give a warning. So the easy solution is to move the inline definitions of getauxval into a header file, which suppresses the warning without requiring me to faff about with further ifdefs to make the definitions conditional on at least one use.
2020-12-24 09:34:13 +00:00
#if defined __arm__ || defined __aarch64__
Support hardware AES on Arm platforms. The refactored sshaes.c gives me a convenient slot to drop in a second hardware-accelerated AES implementation, similar to the existing one but using Arm NEON intrinsics in place of the x86 AES-NI ones. This needed a minor structural change, because Arm systems are often heterogeneous, containing more than one type of CPU which won't necessarily all support the same set of architecture features. So you can't test at run time for the presence of AES acceleration by querying the CPU you're running on - even if you found a way to do it, the answer wouldn't be reliable once the OS started migrating your process between CPUs. Instead, you have to ask the OS itself, because only that knows about _all_ the CPUs on the system. So that means the aes_hw_available() mechanism has to extend a tentacle into each platform subdirectory. The trickiest part was the nest of ifdefs that tries to detect whether the compiler can support the necessary parts. I had successful test-compiles on several compilers, and was able to run the code directly on an AArch64 tablet (so I know it passes cryptsuite), but it's likely that at least some Arm platforms won't be able to build it because of some path through the ifdefs that I haven't been able to test yet.
2019-01-16 22:08:45 +00:00
bool platform_aes_hw_available(void)
{
#if defined HWCAP_AES
return getauxval(AT_HWCAP) & HWCAP_AES;
#elif defined HWCAP2_AES
return getauxval(AT_HWCAP2) & HWCAP2_AES;
#else
return false;
#endif
}
Support hardware SHA-256 and SHA-1 on Arm platforms. Similarly to my recent addition of NEON-accelerated AES, these new implementations drop in alongside the SHA-NI ones, under a different set of ifdefs. All the details of selection and detection are essentially the same as they were for the AES code.
2019-01-23 07:27:12 +00:00
bool platform_sha256_hw_available(void)
{
#if defined HWCAP_SHA2
return getauxval(AT_HWCAP) & HWCAP_SHA2;
#elif defined HWCAP2_SHA2
return getauxval(AT_HWCAP2) & HWCAP2_SHA2;
#else
return false;
#endif
}
bool platform_sha1_hw_available(void)
{
#if defined HWCAP_SHA1
return getauxval(AT_HWCAP) & HWCAP_SHA1;
#elif defined HWCAP2_SHA1
return getauxval(AT_HWCAP2) & HWCAP2_SHA1;
#else
return false;
#endif
}
Support FreeBSD's API for querying the ELF aux vector. We use this for detecting the Arm crypto extension and using it to enable accelerated AES and/or SHA-{1,2}. Previously, I had code that called glibc's getauxval(3) function, conditioned on #ifdef __linux__. Now, instead, I do an autoconf test to query the presence of getauxval itself (so that any other system with the same API can still work), and alongside it, also check for the analogous FreeBSD libc function elf_aux_info(3). As a result, building on Arm FreeBSD now gets the accelerated-crypto autodetection.
2020-10-09 18:14:57 +00:00
#endif /* defined __arm__ || defined __aarch64__ */
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