[arm-platforms:kvm-arm64/nvhe-on-vhe 3/14] arch/arm64/kernel/kaslr.c:65:13: warning: variable 'seed' set but not used
kernel test robot
lkp at intel.com
Sat Mar 26 15:05:51 PDT 2022
tree: https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nvhe-on-vhe
head: b3e5370b9d39ade12b5aad9dbc547bee38fc56a9
commit: 3efdb5446f1dd4a08c73a77c48f710576255d653 [3/14] arm64: Turn kaslr_feature_override into a generic SW feature override
config: arm64-defconfig (https://download.01.org/0day-ci/archive/20220327/202203270615.gXLKqGFi-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?id=3efdb5446f1dd4a08c73a77c48f710576255d653
git remote add arm-platforms https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
git fetch --no-tags arm-platforms kvm-arm64/nvhe-on-vhe
git checkout 3efdb5446f1dd4a08c73a77c48f710576255d653
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/kernel/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>
All warnings (new ones prefixed by >>):
arch/arm64/kernel/kaslr.c:62:12: warning: no previous prototype for 'kaslr_early_init' [-Wmissing-prototypes]
62 | u64 __init kaslr_early_init(void)
| ^~~~~~~~~~~~~~~~
arch/arm64/kernel/kaslr.c: In function 'kaslr_early_init':
arch/arm64/kernel/kaslr.c:99:84: error: expected ')' before '{' token
99 | ARM64_SW_FEATURE_OVERRIDE_NOKASLR) {
| ^~
| )
arch/arm64/kernel/kaslr.c:97:12: note: to match this '('
97 | if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val &
| ^
arch/arm64/kernel/kaslr.c:185:1: error: expected expression before '}' token
185 | }
| ^
arch/arm64/kernel/kaslr.c:66:23: warning: unused variable 'raw' [-Wunused-variable]
66 | unsigned long raw;
| ^~~
arch/arm64/kernel/kaslr.c:65:33: warning: unused variable 'module_range' [-Wunused-variable]
65 | u64 seed, offset, mask, module_range;
| ^~~~~~~~~~~~
arch/arm64/kernel/kaslr.c:65:27: warning: unused variable 'mask' [-Wunused-variable]
65 | u64 seed, offset, mask, module_range;
| ^~~~
arch/arm64/kernel/kaslr.c:65:19: warning: unused variable 'offset' [-Wunused-variable]
65 | u64 seed, offset, mask, module_range;
| ^~~~~~
>> arch/arm64/kernel/kaslr.c:65:13: warning: variable 'seed' set but not used [-Wunused-but-set-variable]
65 | u64 seed, offset, mask, module_range;
| ^~~~
arch/arm64/kernel/kaslr.c:185:1: error: control reaches end of non-void function [-Werror=return-type]
185 | }
| ^
cc1: some warnings being treated as errors
vim +/seed +65 arch/arm64/kernel/kaslr.c
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 53
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 54 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 55 * This routine will be executed with the kernel mapped at its default virtual
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 56 * address, and if it returns successfully, the kernel will be remapped, and
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 57 * start_kernel() will be executed from a randomized virtual offset. The
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 58 * relocation will result in all absolute references (e.g., static variables
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 59 * containing function pointers) to be reinitialized, and zero-initialized
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 60 * .bss variables will be reset to 0.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 61 */
f6f0c4362f070ca Marc Zyngier 2021-02-08 62 u64 __init kaslr_early_init(void)
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 63 {
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 64 void *fdt;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 @65 u64 seed, offset, mask, module_range;
9bceb80b3cc483e Guenter Roeck 2020-08-07 66 unsigned long raw;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 67
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 68 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 69 * Set a reasonable default for module_alloc_base in case
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 70 * we end up running with module randomization disabled.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 71 */
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 72 module_alloc_base = (u64)_etext - MODULES_VSIZE;
fade9c2c6ee2bae Fuad Tabba 2021-05-24 73 dcache_clean_inval_poc((unsigned long)&module_alloc_base,
814b186079cd54d Fuad Tabba 2021-05-24 74 (unsigned long)&module_alloc_base +
814b186079cd54d Fuad Tabba 2021-05-24 75 sizeof(module_alloc_base));
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 76
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 77 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 78 * Try to map the FDT early. If this fails, we simply bail,
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 79 * and proceed with KASLR disabled. We will make another
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 80 * attempt at mapping the FDT in setup_machine()
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 81 */
f6f0c4362f070ca Marc Zyngier 2021-02-08 82 fdt = get_early_fdt_ptr();
294a9ddde6cdbf9 Mark Brown 2019-11-08 83 if (!fdt) {
294a9ddde6cdbf9 Mark Brown 2019-11-08 84 kaslr_status = KASLR_DISABLED_FDT_REMAP;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 85 return 0;
294a9ddde6cdbf9 Mark Brown 2019-11-08 86 }
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 87
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 88 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 89 * Retrieve (and wipe) the seed from the FDT
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 90 */
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 91 seed = get_kaslr_seed(fdt);
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 92
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 93 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 94 * Check if 'nokaslr' appears on the command line, and
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 95 * return 0 if that is the case.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 96 */
3efdb5446f1dd4a Marc Zyngier 2022-03-24 97 if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val &
3efdb5446f1dd4a Marc Zyngier 2022-03-24 98 arm64_sw_feature_override.mask,
3efdb5446f1dd4a Marc Zyngier 2022-03-24 99 ARM64_SW_FEATURE_OVERRIDE_NOKASLR) {
294a9ddde6cdbf9 Mark Brown 2019-11-08 100 kaslr_status = KASLR_DISABLED_CMDLINE;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 101 return 0;
294a9ddde6cdbf9 Mark Brown 2019-11-08 102 }
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 103
2e8e1ea88cbcb19 Mark Brown 2020-01-21 104 /*
9bceb80b3cc483e Guenter Roeck 2020-08-07 105 * Mix in any entropy obtainable architecturally if enabled
9bceb80b3cc483e Guenter Roeck 2020-08-07 106 * and supported.
2e8e1ea88cbcb19 Mark Brown 2020-01-21 107 */
2e8e1ea88cbcb19 Mark Brown 2020-01-21 108
9bceb80b3cc483e Guenter Roeck 2020-08-07 109 if (arch_get_random_seed_long_early(&raw))
2e8e1ea88cbcb19 Mark Brown 2020-01-21 110 seed ^= raw;
2e8e1ea88cbcb19 Mark Brown 2020-01-21 111
2203e1adb936a92 Mark Brown 2019-11-08 112 if (!seed) {
2203e1adb936a92 Mark Brown 2019-11-08 113 kaslr_status = KASLR_DISABLED_NO_SEED;
2203e1adb936a92 Mark Brown 2019-11-08 114 return 0;
2203e1adb936a92 Mark Brown 2019-11-08 115 }
2203e1adb936a92 Mark Brown 2019-11-08 116
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 117 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 118 * OK, so we are proceeding with KASLR enabled. Calculate a suitable
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 119 * kernel image offset from the seed. Let's place the kernel in the
90ec95cda91a021 Steve Capper 2019-08-07 120 * middle half of the VMALLOC area (VA_BITS_MIN - 2), and stay clear of
f2b9ba871beb92f Ard Biesheuvel 2018-03-06 121 * the lower and upper quarters to avoid colliding with other
f2b9ba871beb92f Ard Biesheuvel 2018-03-06 122 * allocations.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 123 * Even if we could randomize at page granularity for 16k and 64k pages,
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 124 * let's always round to 2 MB so we don't interfere with the ability to
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 125 * map using contiguous PTEs
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 126 */
90ec95cda91a021 Steve Capper 2019-08-07 127 mask = ((1UL << (VA_BITS_MIN - 2)) - 1) & ~(SZ_2M - 1);
90ec95cda91a021 Steve Capper 2019-08-07 128 offset = BIT(VA_BITS_MIN - 3) + (seed & mask);
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 129
c031a4213c11a5d Ard Biesheuvel 2016-01-29 130 /* use the top 16 bits to randomize the linear region */
c031a4213c11a5d Ard Biesheuvel 2016-01-29 131 memstart_offset_seed = seed >> 48;
c031a4213c11a5d Ard Biesheuvel 2016-01-29 132
31d02e7ab00873b Lecopzer Chen 2021-03-24 133 if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) &&
31d02e7ab00873b Lecopzer Chen 2021-03-24 134 (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
31d02e7ab00873b Lecopzer Chen 2021-03-24 135 IS_ENABLED(CONFIG_KASAN_SW_TAGS)))
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 136 /*
31d02e7ab00873b Lecopzer Chen 2021-03-24 137 * KASAN without KASAN_VMALLOC does not expect the module region
31d02e7ab00873b Lecopzer Chen 2021-03-24 138 * to intersect the vmalloc region, since shadow memory is
31d02e7ab00873b Lecopzer Chen 2021-03-24 139 * allocated for each module at load time, whereas the vmalloc
31d02e7ab00873b Lecopzer Chen 2021-03-24 140 * region is shadowed by KASAN zero pages. So keep modules
31d02e7ab00873b Lecopzer Chen 2021-03-24 141 * out of the vmalloc region if KASAN is enabled without
31d02e7ab00873b Lecopzer Chen 2021-03-24 142 * KASAN_VMALLOC, and put the kernel well within 4 GB of the
31d02e7ab00873b Lecopzer Chen 2021-03-24 143 * module region.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 144 */
f2b9ba871beb92f Ard Biesheuvel 2018-03-06 145 return offset % SZ_2G;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 146
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 147 if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) {
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 148 /*
b2eed9b58811283 Ard Biesheuvel 2019-05-23 149 * Randomize the module region over a 2 GB window covering the
f2b9ba871beb92f Ard Biesheuvel 2018-03-06 150 * kernel. This reduces the risk of modules leaking information
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 151 * about the address of the kernel itself, but results in
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 152 * branches between modules and the core kernel that are
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 153 * resolved via PLTs. (Branches between modules will be
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 154 * resolved normally.)
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 155 */
b2eed9b58811283 Ard Biesheuvel 2019-05-23 156 module_range = SZ_2G - (u64)(_end - _stext);
b2eed9b58811283 Ard Biesheuvel 2019-05-23 157 module_alloc_base = max((u64)_end + offset - SZ_2G,
f2b9ba871beb92f Ard Biesheuvel 2018-03-06 158 (u64)MODULES_VADDR);
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 159 } else {
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 160 /*
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 161 * Randomize the module region by setting module_alloc_base to
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 162 * a PAGE_SIZE multiple in the range [_etext - MODULES_VSIZE,
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 163 * _stext) . This guarantees that the resulting region still
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 164 * covers [_stext, _etext], and that all relative branches can
f9c4ff2ab9fe433 Barry Song 2021-07-31 165 * be resolved without veneers unless this region is exhausted
f9c4ff2ab9fe433 Barry Song 2021-07-31 166 * and we fall back to a larger 2GB window in module_alloc()
f9c4ff2ab9fe433 Barry Song 2021-07-31 167 * when ARM64_MODULE_PLTS is enabled.
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 168 */
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 169 module_range = MODULES_VSIZE - (u64)(_etext - _stext);
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 170 module_alloc_base = (u64)_etext + offset - MODULES_VSIZE;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 171 }
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 172
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 173 /* use the lower 21 bits to randomize the base of the module region */
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 174 module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 175 module_alloc_base &= PAGE_MASK;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 176
fade9c2c6ee2bae Fuad Tabba 2021-05-24 177 dcache_clean_inval_poc((unsigned long)&module_alloc_base,
814b186079cd54d Fuad Tabba 2021-05-24 178 (unsigned long)&module_alloc_base +
814b186079cd54d Fuad Tabba 2021-05-24 179 sizeof(module_alloc_base));
fade9c2c6ee2bae Fuad Tabba 2021-05-24 180 dcache_clean_inval_poc((unsigned long)&memstart_offset_seed,
814b186079cd54d Fuad Tabba 2021-05-24 181 (unsigned long)&memstart_offset_seed +
814b186079cd54d Fuad Tabba 2021-05-24 182 sizeof(memstart_offset_seed));
1598ecda7b239e9 Ard Biesheuvel 2019-01-15 183
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 184 return offset;
f80fb3a3d50843a Ard Biesheuvel 2016-01-26 185 }
294a9ddde6cdbf9 Mark Brown 2019-11-08 186
:::::: The code at line 65 was first introduced by commit
:::::: f80fb3a3d50843a401dac4b566b3b131da8077a2 arm64: add support for kernel ASLR
:::::: TO: Ard Biesheuvel <ard.biesheuvel at linaro.org>
:::::: CC: Catalin Marinas <catalin.marinas at arm.com>
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