Re: arch/riscv/mm/init.c:1204:48: sparse: sparse: cast truncates bits from constant value (100000000 becomes 0)

From: Randy Dunlap
Date: Sat Jun 17 2023 - 19:47:33 EST

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+ Nick
+ linux-riscv

On 5/17/23 03:09, kernel test robot wrote:
> Hi Yimin,
>
> FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6
> commit: b5e2c507b06c9d36411845149162a804ae7b04a9 riscv: Kconfig: Allow RV32 to build with no MMU
> date: 7 weeks ago
> config: riscv-randconfig-s041-20230517
> compiler: riscv32-linux-gcc (GCC) 12.1.0
> reproduce:
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # apt-get install sparse
> # sparse version: v0.6.4-39-gce1a6720-dirty
> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b5e2c507b06c9d36411845149162a804ae7b04a9
> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout b5e2c507b06c9d36411845149162a804ae7b04a9
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=riscv olddefconfig
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/mm/ fs/ext4/
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202305171743.3LP5XWzV-lkp@xxxxxxxxx/
>
> sparse warnings: (new ones prefixed by >>)
> WARNING: invalid argument to '-march': '_zihintpause'
>>> arch/riscv/mm/init.c:1204:48: sparse: sparse: cast truncates bits from constant value (100000000 becomes 0)

^^^ please see below.

> --
> WARNING: invalid argument to '-march': '_zihintpause'
> fs/ext4/mballoc.c: note: in included file (through include/linux/timex.h, include/linux/time32.h, include/linux/time.h, ...):
>>> arch/riscv/include/asm/timex.h:25:16: sparse: sparse: cast removes address space '__iomem' of expression
>>> arch/riscv/include/asm/timex.h:25:16: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const volatile [noderef] __iomem *addr @@ got unsigned int [usertype] * @@
> arch/riscv/include/asm/timex.h:25:16: sparse: expected void const volatile [noderef] __iomem *addr
> arch/riscv/include/asm/timex.h:25:16: sparse: got unsigned int [usertype] *
>>> arch/riscv/include/asm/timex.h:25:16: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const volatile [noderef] __iomem *addr @@ got unsigned int [usertype] * @@
> arch/riscv/include/asm/timex.h:25:16: sparse: expected void const volatile [noderef] __iomem *addr
> arch/riscv/include/asm/timex.h:25:16: sparse: got unsigned int [usertype] *
> fs/ext4/mballoc.c:2942:13: sparse: sparse: context imbalance in 'ext4_mb_seq_structs_summary_start' - wrong count at exit
>
> vim +1204 arch/riscv/mm/init.c
>
> 671f9a3e2e24cd Anup Patel 2019-06-28 1154
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1155 /*
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1156 * reserve_crashkernel() - reserves memory for crash kernel
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1157 *
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1158 * This function reserves memory area given in "crashkernel=" kernel command
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1159 * line parameter. The memory reserved is used by dump capture kernel when
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1160 * primary kernel is crashing.
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1161 */
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1162 static void __init reserve_crashkernel(void)
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1163 {
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1164 unsigned long long crash_base = 0;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1165 unsigned long long crash_size = 0;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1166 unsigned long search_start = memblock_start_of_DRAM();
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1167 unsigned long search_end = memblock_end_of_DRAM();
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1168
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1169 int ret = 0;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1170
> d414cb379ac35e Jisheng Zhang 2022-03-23 1171 if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> d414cb379ac35e Jisheng Zhang 2022-03-23 1172 return;
> 5640975003d023 Nick Kossifidis 2021-04-19 1173 /*
> 5640975003d023 Nick Kossifidis 2021-04-19 1174 * Don't reserve a region for a crash kernel on a crash kernel
> 5640975003d023 Nick Kossifidis 2021-04-19 1175 * since it doesn't make much sense and we have limited memory
> 5640975003d023 Nick Kossifidis 2021-04-19 1176 * resources.
> 5640975003d023 Nick Kossifidis 2021-04-19 1177 */
> 5640975003d023 Nick Kossifidis 2021-04-19 1178 if (is_kdump_kernel()) {
> 5640975003d023 Nick Kossifidis 2021-04-19 1179 pr_info("crashkernel: ignoring reservation request\n");
> 5640975003d023 Nick Kossifidis 2021-04-19 1180 return;
> 5640975003d023 Nick Kossifidis 2021-04-19 1181 }
> 5640975003d023 Nick Kossifidis 2021-04-19 1182
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1183 ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1184 &crash_size, &crash_base);
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1185 if (ret || !crash_size)
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1186 return;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1187
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1188 crash_size = PAGE_ALIGN(crash_size);
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1189
> a7259df7670240 Mike Rapoport 2021-09-02 1190 if (crash_base) {
> a7259df7670240 Mike Rapoport 2021-09-02 1191 search_start = crash_base;
> a7259df7670240 Mike Rapoport 2021-09-02 1192 search_end = crash_base + crash_size;
> a7259df7670240 Mike Rapoport 2021-09-02 1193 }
> a7259df7670240 Mike Rapoport 2021-09-02 1194
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1195 /*
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1196 * Current riscv boot protocol requires 2MB alignment for
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1197 * RV64 and 4MB alignment for RV32 (hugepage size)
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1198 *
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1199 * Try to alloc from 32bit addressible physical memory so that
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1200 * swiotlb can work on the crash kernel.
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1201 */
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1202 crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1203 search_start,
> decf89f86ecd3c Nick Kossifidis 2021-11-26 @1204 min(search_end, (unsigned long) SZ_4G));

SZ_4G = 0x100000000, truncated to unsigned long (32 bits), becomes 0, so min() is 0.
Or am I not following this correctly?

Should the second param to min() be changed to SZ_4G - 1
or is this not an issue?

> decf89f86ecd3c Nick Kossifidis 2021-11-26 1205 if (crash_base == 0) {
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1206 /* Try again without restricting region to 32bit addressible memory */
> a7259df7670240 Mike Rapoport 2021-09-02 1207 crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
> a7259df7670240 Mike Rapoport 2021-09-02 1208 search_start, search_end);
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1209 if (crash_base == 0) {
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1210 pr_warn("crashkernel: couldn't allocate %lldKB\n",
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1211 crash_size >> 10);
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1212 return;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1213 }
> decf89f86ecd3c Nick Kossifidis 2021-11-26 1214 }
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1215
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1216 pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n",
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1217 crash_base, crash_base + crash_size, crash_size >> 20);
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1218
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1219 crashk_res.start = crash_base;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1220 crashk_res.end = crash_base + crash_size - 1;
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1221 }
> e53d28180d4d0f Nick Kossifidis 2021-04-19 1222
>
> :::::: The code at line 1204 was first introduced by commit
> :::::: decf89f86ecd3c3c3de81c562010d5797bea3de1 riscv: try to allocate crashkern region from 32bit addressible memory
>
> :::::: TO: Nick Kossifidis <mick@xxxxxxxxxxxx>
> :::::: CC: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
>

Thanks.
--
~Randy

Next message: Mike Kravetz: "Re: [PATCH v1 1/3] mm/hwpoison: find subpage in hugetlb HWPOISON list"
Previous message: Ondřej Jirman: "[PATCH v2] drm: bridge: dw-mipi-dsi: Fix enable/disable of DSI controller"
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