* arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
@ 2021-08-23 10:59 kernel test robot
2021-08-23 14:35 ` Christophe Leroy
0 siblings, 1 reply; 5+ messages in thread
From: kernel test robot @ 2021-08-23 10:59 UTC (permalink / raw)
To: Christophe Leroy
Cc: clang-built-linux, kbuild-all, linux-kernel, Michael Ellerman
[-- Attachment #1: Type: text/plain, Size: 21733 bytes --]
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93
commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version
date: 9 months ago
config: powerpc-randconfig-c003-20210821 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa)
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
# install powerpc cross compiling tool for clang build
# apt-get install binutils-powerpc-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout ef75e73182949a94bde169a774de1b62ae21fbbc
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc clang-analyzer
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
clang-analyzer warnings: (new ones prefixed by >>)
^
crypto/ecc.c:880:7: note: Assuming the condition is false
if (EVEN(a)) {
^
crypto/ecc.c:853:20: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
^~~~~~~~~~~~~
crypto/ecc.c:880:3: note: Taking false branch
if (EVEN(a)) {
^
crypto/ecc.c:889:14: note: Assuming the condition is true
} else if (EVEN(b)) {
^
crypto/ecc.c:853:20: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
^~~~~~~~~~~~~
crypto/ecc.c:889:10: note: Taking true branch
} else if (EVEN(b)) {
^
crypto/ecc.c:892:9: note: The left operand of '&' is a garbage value
if (!EVEN(v))
^
crypto/ecc.c:853:29: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
~~~~~~ ^
crypto/ecc.c:920:9: warning: The left operand of '&' is a garbage value [clang-analyzer-core.UndefinedBinaryOperatorResult]
if (!EVEN(v))
^
crypto/ecc.c:853:29: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
^
crypto/ecc.c:1245:2: note: Calling 'ecc_point_add'
ecc_point_add(&sum, p, q, curve);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:1221:2: note: Calling 'vli_mod_inv'
vli_mod_inv(z, z, curve->p, ndigits);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:866:6: note: Assuming the condition is false
if (vli_is_zero(input, ndigits)) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:866:2: note: Taking false branch
if (vli_is_zero(input, ndigits)) {
^
crypto/ecc.c:875:2: note: Calling 'vli_clear'
vli_clear(v, ndigits);
^~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:113:2: note: Loop condition is false. Execution continues on line 113
for (i = 0; i < ndigits; i++)
^
crypto/ecc.c:115:1: note: Returning without writing to '*vli'
}
^
crypto/ecc.c:875:2: note: Returning from 'vli_clear'
vli_clear(v, ndigits);
^~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:877:9: note: Assuming the condition is true
while ((cmp_result = vli_cmp(a, b, ndigits)) != 0) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:877:2: note: Loop condition is true. Entering loop body
while ((cmp_result = vli_cmp(a, b, ndigits)) != 0) {
^
crypto/ecc.c:880:7: note: Assuming the condition is false
if (EVEN(a)) {
^
crypto/ecc.c:853:20: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
^~~~~~~~~~~~~
crypto/ecc.c:880:3: note: Taking false branch
if (EVEN(a)) {
^
crypto/ecc.c:889:14: note: Assuming the condition is false
} else if (EVEN(b)) {
^
crypto/ecc.c:853:20: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
^~~~~~~~~~~~~
crypto/ecc.c:889:10: note: Taking false branch
} else if (EVEN(b)) {
^
crypto/ecc.c:898:14: note: Assuming 'cmp_result' is <= 0
} else if (cmp_result > 0) {
^~~~~~~~~~~~~~
crypto/ecc.c:898:10: note: Taking false branch
} else if (cmp_result > 0) {
^
crypto/ecc.c:916:8: note: Assuming the condition is false
if (vli_cmp(v, u, ndigits) < 0)
^~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/ecc.c:916:4: note: Taking false branch
if (vli_cmp(v, u, ndigits) < 0)
^
crypto/ecc.c:920:9: note: The left operand of '&' is a garbage value
if (!EVEN(v))
^
crypto/ecc.c:853:29: note: expanded from macro 'EVEN'
#define EVEN(vli) (!(vli[0] & 1))
~~~~~~ ^
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
5 warnings generated.
>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
msr &= ~MSR_VSX;
^ ~~~~~~~~
arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to 'msr' is never read
msr &= ~MSR_VSX;
^ ~~~~~~~~
arch/powerpc/kernel/signal_32.c:765:16: warning: Value stored to 'msr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
unsigned long msr = regs->msr;
^~~ ~~~~~~~~~
arch/powerpc/kernel/signal_32.c:765:16: note: Value stored to 'msr' during its initialization is never read
unsigned long msr = regs->msr;
^~~ ~~~~~~~~~
arch/powerpc/kernel/signal_32.c:869:16: warning: Value stored to 'msr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
unsigned long msr = regs->msr;
^~~ ~~~~~~~~~
arch/powerpc/kernel/signal_32.c:869:16: note: Value stored to 'msr' during its initialization is never read
unsigned long msr = regs->msr;
^~~ ~~~~~~~~~
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
2 warnings generated.
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
3 warnings generated.
arch/powerpc/kernel/vdso.c:251:8: warning: Dereference of null pointer (loaded from variable 'size') [clang-analyzer-core.NullDereference]
*size = 0;
^
arch/powerpc/kernel/vdso.c:750:6: note: Calling 'vdso_setup'
if (vdso_setup()) {
^~~~~~~~~~~~
arch/powerpc/kernel/vdso.c:618:6: note: Calling 'vdso_do_find_sections'
if (vdso_do_find_sections(&v32, &v64))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/kernel/vdso.c:440:52: note: Passing null pointer value via 3rd parameter 'size'
v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
^
include/linux/stddef.h:8:14: note: expanded from macro 'NULL'
#define NULL ((void *)0)
^~~~~~~~~~~
arch/powerpc/kernel/vdso.c:440:16: note: Calling 'find_section32'
v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/kernel/vdso.c:244:14: note: 'i' is >= field 'e_shnum'
for (i = 1; i < ehdr->e_shnum; i++) {
^
arch/powerpc/kernel/vdso.c:244:2: note: Loop condition is false. Execution continues on line 251
for (i = 1; i < ehdr->e_shnum; i++) {
^
arch/powerpc/kernel/vdso.c:251:8: note: Dereference of null pointer (loaded from variable 'size')
*size = 0;
~~~~ ^
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
2 warnings generated.
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
2 warnings generated.
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
2 warnings generated.
Suppressed 2 warnings (1 in non-user code, 1 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
6 warnings generated.
fs/fscache/object.c:284:2: warning: Value stored to 'start' is never read [clang-analyzer-deadcode.DeadStores]
start = jiffies;
^ ~~~~~~~
fs/fscache/object.c:284:2: note: Value stored to 'start' is never read
start = jiffies;
^ ~~~~~~~
fs/fscache/object.c:454:25: warning: Value stored to 'cookie' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
struct fscache_cookie *cookie = object->cookie;
^~~~~~ ~~~~~~~~~~~~~~
fs/fscache/object.c:454:25: note: Value stored to 'cookie' during its initialization is never read
struct fscache_cookie *cookie = object->cookie;
^~~~~~ ~~~~~~~~~~~~~~
Suppressed 4 warnings (1 in non-user code, 3 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
4 warnings generated.
fs/fscache/operation.c:627:2: warning: Value stored to 'start' is never read [clang-analyzer-deadcode.DeadStores]
start = jiffies;
^ ~~~~~~~
fs/fscache/operation.c:627:2: note: Value stored to 'start' is never read
start = jiffies;
^ ~~~~~~~
Suppressed 3 warnings (1 in non-user code, 2 with check filters).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
7 warnings generated.
fs/fscache/page.c:354:2: warning: Value stored to 'jif' is never read [clang-analyzer-deadcode.DeadStores]
jif = jiffies;
^ ~~~~~~~
fs/fscache/page.c:354:2: note: Value stored to 'jif' is never read
jif = jiffies;
^ ~~~~~~~
fs/fscache/page.c:409:32: warning: Value stored to 'state' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
enum fscache_operation_state state = op->state;
^~~~~ ~~~~~~~~~
fs/fscache/page.c:409:32: note: Value stored to 'state' during its initialization is never read
enum fscache_operation_state state = op->state;
^~~~~ ~~~~~~~~~
fs/fscache/page.c:998:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores]
ret = -ENOBUFS;
vim +/msr +297 arch/powerpc/kernel/signal_32.c
968c4fccd1bb8b arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 262
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 263 static int save_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
8d33001dd650b8 arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 264 struct mcontext __user *tm_frame, int ctx_has_vsx_region)
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 265 {
9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 266 unsigned long msr = regs->msr;
9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 267
c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 268 /* save general registers */
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 269 unsafe_save_general_regs(regs, frame, failed);
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 270
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 271 #ifdef CONFIG_ALTIVEC
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 272 /* save altivec registers */
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 273 if (current->thread.used_vr) {
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 274 unsafe_copy_to_user(&frame->mc_vregs, ¤t->thread.vr_state,
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 275 ELF_NVRREG * sizeof(vector128), failed);
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 276 /* set MSR_VEC in the saved MSR value to indicate that
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 277 frame->mc_vregs contains valid data */
9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 278 msr |= MSR_VEC;
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 279 }
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 280 /* else assert((regs->msr & MSR_VEC) == 0) */
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 281
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 282 /* We always copy to/from vrsave, it's 0 if we don't have or don't
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 283 * use altivec. Since VSCR only contains 32 bits saved in the least
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 284 * significant bits of a vector, we "cheat" and stuff VRSAVE in the
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 285 * most significant bits of that same vector. --BenH
408a7e08b2112f arch/powerpc/kernel/signal_32.c Paul Mackerras 2013-08-05 286 * Note that the current VRSAVE value is in the SPR at this point.
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 287 */
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 288 unsafe_put_user(current->thread.vrsave, (u32 __user *)&frame->mc_vregs[32],
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 289 failed);
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 290 #endif /* CONFIG_ALTIVEC */
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 291 unsafe_copy_fpr_to_user(&frame->mc_fregs, current, failed);
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 292
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 293 /*
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 294 * Clear the MSR VSX bit to indicate there is no valid state attached
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 295 * to this context, except in the specific case below where we set it.
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 296 */
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 @297 msr &= ~MSR_VSX;
6a274c08f2f4df arch/powerpc/kernel/signal_32.c Michael Neuling 2008-07-02 298 #ifdef CONFIG_VSX
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 299 /*
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 300 * Copy VSR 0-31 upper half from thread_struct to local
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 301 * buffer, then write that to userspace. Also set MSR_VSX in
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 302 * the saved MSR value to indicate that frame->mc_vregs
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 303 * contains valid data
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 304 */
16c29d180becc5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-10-23 305 if (current->thread.used_vsr && ctx_has_vsx_region) {
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 306 unsafe_copy_vsx_to_user(&frame->mc_vsregs, current, failed);
ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 307 msr |= MSR_VSX;
ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 308 }
c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 309 #endif /* CONFIG_VSX */
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 310 #ifdef CONFIG_SPE
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 311 /* save spe registers */
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 312 if (current->thread.used_spe) {
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 313 unsafe_copy_to_user(&frame->mc_vregs, current->thread.evr,
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 314 ELF_NEVRREG * sizeof(u32), failed);
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 315 /* set MSR_SPE in the saved MSR value to indicate that
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 316 frame->mc_vregs contains valid data */
9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 317 msr |= MSR_SPE;
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 318 }
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 319 /* else assert((regs->msr & MSR_SPE) == 0) */
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 320
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 321 /* We always copy to/from spefscr */
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 322 unsafe_put_user(current->thread.spefscr,
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 323 (u32 __user *)&frame->mc_vregs + ELF_NEVRREG, failed);
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 324 #endif /* CONFIG_SPE */
81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 325
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 327
1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 328 /* We need to write 0 the MSR top 32 bits in the tm frame so that we
1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 329 * can check it on the restore to see if TM is active
1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 330 */
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 331 if (tm_frame)
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 332 unsafe_put_user(0, &tm_frame->mc_gregs[PT_MSR], failed);
1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 333
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 334 return 0;
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 335
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 336 failed:
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 337 return 1;
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 338 }
^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 339
:::::: The code at line 297 was first introduced by commit
:::::: ec67ad82814bee92251fd963bf01c7a173856555 powerpc/signals: Improved mark VSX not saved with small contexts fix
:::::: TO: Michael Neuling <mikey@neuling.org>
:::::: CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 37159 bytes --]
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
2021-08-23 10:59 arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores] kernel test robot
@ 2021-08-23 14:35 ` Christophe Leroy
2021-08-24 6:59 ` [kbuild-all] " Chen, Rong A
0 siblings, 1 reply; 5+ messages in thread
From: Christophe Leroy @ 2021-08-23 14:35 UTC (permalink / raw)
To: kernel test robot
Cc: clang-built-linux, kbuild-all, linux-kernel, Michael Ellerman
Le 23/08/2021 à 12:59, kernel test robot a écrit :
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93
> commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version
> date: 9 months ago
> config: powerpc-randconfig-c003-20210821 (attached as .config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa)
> 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
> # install powerpc cross compiling tool for clang build
> # apt-get install binutils-powerpc-linux-gnu
> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc
> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout ef75e73182949a94bde169a774de1b62ae21fbbc
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc clang-analyzer
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
>
> clang-analyzer warnings: (new ones prefixed by >>)
> ^
>>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
> msr &= ~MSR_VSX;
> ^ ~~~~~~~~
> arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to 'msr' is never read
> msr &= ~MSR_VSX;
> ^ ~~~~~~~~
This is wrong.
msr is used at line 326:
ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 326
unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
> arch/powerpc/kernel/signal_32.c:765:16: warning: Value stored to 'msr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
> unsigned long msr = regs->msr;
> ^~~ ~~~~~~~~~
> arch/powerpc/kernel/signal_32.c:765:16: note: Value stored to 'msr' during its initialization is never read
> unsigned long msr = regs->msr;
> ^~~ ~~~~~~~~~
> arch/powerpc/kernel/signal_32.c:869:16: warning: Value stored to 'msr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
> unsigned long msr = regs->msr;
> ^~~ ~~~~~~~~~
> arch/powerpc/kernel/signal_32.c:869:16: note: Value stored to 'msr' during its initialization is never read
> unsigned long msr = regs->msr;
> ^~~ ~~~~~~~~~
>
> vim +/msr +297 arch/powerpc/kernel/signal_32.c
>
> 968c4fccd1bb8b arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 262
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 263 static int save_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
> 8d33001dd650b8 arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 264 struct mcontext __user *tm_frame, int ctx_has_vsx_region)
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 265 {
> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 266 unsigned long msr = regs->msr;
> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 267
> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 268 /* save general registers */
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 269 unsafe_save_general_regs(regs, frame, failed);
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 270
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 271 #ifdef CONFIG_ALTIVEC
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 272 /* save altivec registers */
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 273 if (current->thread.used_vr) {
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 274 unsafe_copy_to_user(&frame->mc_vregs, ¤t->thread.vr_state,
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 275 ELF_NVRREG * sizeof(vector128), failed);
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 276 /* set MSR_VEC in the saved MSR value to indicate that
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 277 frame->mc_vregs contains valid data */
> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 278 msr |= MSR_VEC;
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 279 }
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 280 /* else assert((regs->msr & MSR_VEC) == 0) */
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 281
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 282 /* We always copy to/from vrsave, it's 0 if we don't have or don't
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 283 * use altivec. Since VSCR only contains 32 bits saved in the least
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 284 * significant bits of a vector, we "cheat" and stuff VRSAVE in the
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 285 * most significant bits of that same vector. --BenH
> 408a7e08b2112f arch/powerpc/kernel/signal_32.c Paul Mackerras 2013-08-05 286 * Note that the current VRSAVE value is in the SPR at this point.
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 287 */
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 288 unsafe_put_user(current->thread.vrsave, (u32 __user *)&frame->mc_vregs[32],
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 289 failed);
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 290 #endif /* CONFIG_ALTIVEC */
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 291 unsafe_copy_fpr_to_user(&frame->mc_fregs, current, failed);
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 292
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 293 /*
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 294 * Clear the MSR VSX bit to indicate there is no valid state attached
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 295 * to this context, except in the specific case below where we set it.
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 296 */
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 @297 msr &= ~MSR_VSX;
> 6a274c08f2f4df arch/powerpc/kernel/signal_32.c Michael Neuling 2008-07-02 298 #ifdef CONFIG_VSX
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 299 /*
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 300 * Copy VSR 0-31 upper half from thread_struct to local
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 301 * buffer, then write that to userspace. Also set MSR_VSX in
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 302 * the saved MSR value to indicate that frame->mc_vregs
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 303 * contains valid data
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 304 */
> 16c29d180becc5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-10-23 305 if (current->thread.used_vsr && ctx_has_vsx_region) {
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 306 unsafe_copy_vsx_to_user(&frame->mc_vsregs, current, failed);
> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 307 msr |= MSR_VSX;
> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling 2013-11-25 308 }
> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 309 #endif /* CONFIG_VSX */
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 310 #ifdef CONFIG_SPE
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 311 /* save spe registers */
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 312 if (current->thread.used_spe) {
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 313 unsafe_copy_to_user(&frame->mc_vregs, current->thread.evr,
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 314 ELF_NEVRREG * sizeof(u32), failed);
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 315 /* set MSR_SPE in the saved MSR value to indicate that
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 316 frame->mc_vregs contains valid data */
> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling 2008-06-25 317 msr |= MSR_SPE;
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 318 }
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 319 /* else assert((regs->msr & MSR_SPE) == 0) */
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 320
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 321 /* We always copy to/from spefscr */
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 322 unsafe_put_user(current->thread.spefscr,
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 323 (u32 __user *)&frame->mc_vregs + ELF_NEVRREG, failed);
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 324 #endif /* CONFIG_SPE */
> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell 2005-10-18 325
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 327
> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 328 /* We need to write 0 the MSR top 32 bits in the tm frame so that we
> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 329 * can check it on the restore to see if TM is active
> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 330 */
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 331 if (tm_frame)
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 332 unsafe_put_user(0, &tm_frame->mc_gregs[PT_MSR], failed);
> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling 2013-06-09 333
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 334 return 0;
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 335
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 336 failed:
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 337 return 1;
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 338 }
> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds 2005-04-16 339
>
> :::::: The code at line 297 was first introduced by commit
> :::::: ec67ad82814bee92251fd963bf01c7a173856555 powerpc/signals: Improved mark VSX not saved with small contexts fix
>
> :::::: TO: Michael Neuling <mikey@neuling.org>
> :::::: CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [kbuild-all] Re: arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
2021-08-23 14:35 ` Christophe Leroy
@ 2021-08-24 6:59 ` Chen, Rong A
2021-08-24 7:29 ` Christophe Leroy
0 siblings, 1 reply; 5+ messages in thread
From: Chen, Rong A @ 2021-08-24 6:59 UTC (permalink / raw)
To: Christophe Leroy, kernel test robot
Cc: clang-built-linux, kbuild-all, linux-kernel, Michael Ellerman
On 8/23/2021 10:35 PM, Christophe Leroy wrote:
>
>
> Le 23/08/2021 à 12:59, kernel test robot a écrit :
>> tree:
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93
>> commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32:
>> Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version
>> date: 9 months ago
>> config: powerpc-randconfig-c003-20210821 (attached as .config)
>> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
>> d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa)
>> 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
>> # install powerpc cross compiling tool for clang build
>> # apt-get install binutils-powerpc-linux-gnu
>> #
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc
>>
>> git remote add linus
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>> git fetch --no-tags linus master
>> git checkout ef75e73182949a94bde169a774de1b62ae21fbbc
>> # save the attached .config to linux build tree
>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross
>> ARCH=powerpc clang-analyzer
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>>
>> clang-analyzer warnings: (new ones prefixed by >>)
>> ^
>>>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to
>>>> 'msr' is never read [clang-analyzer-deadcode.DeadStores]
>> msr &= ~MSR_VSX;
>> ^ ~~~~~~~~
>> arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to 'msr'
>> is never read
>> msr &= ~MSR_VSX;
>> ^ ~~~~~~~~
>
>
> This is wrong.
>
> msr is used at line 326:
>
> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
> 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
Hi Christophe,
The usage is under CONFIG_VSX, the test config
(powerpc-randconfig-c003-20210821) didn't enable it which triggered this
warning.
Best Regards,
Rong Chen
>
>
>
>
>
>> arch/powerpc/kernel/signal_32.c:765:16: warning: Value stored to
>> 'msr' during its initialization is never read
>> [clang-analyzer-deadcode.DeadStores]
>> unsigned long msr = regs->msr;
>> ^~~ ~~~~~~~~~
>> arch/powerpc/kernel/signal_32.c:765:16: note: Value stored to
>> 'msr' during its initialization is never read
>> unsigned long msr = regs->msr;
>> ^~~ ~~~~~~~~~
>> arch/powerpc/kernel/signal_32.c:869:16: warning: Value stored to
>> 'msr' during its initialization is never read
>> [clang-analyzer-deadcode.DeadStores]
>> unsigned long msr = regs->msr;
>> ^~~ ~~~~~~~~~
>> arch/powerpc/kernel/signal_32.c:869:16: note: Value stored to
>> 'msr' during its initialization is never read
>> unsigned long msr = regs->msr;
>> ^~~ ~~~~~~~~~
>>
>> vim +/msr +297 arch/powerpc/kernel/signal_32.c
>>
>> 968c4fccd1bb8b arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 262
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 263 static int save_user_regs_unsafe(struct pt_regs
>> *regs, struct mcontext __user *frame,
>> 8d33001dd650b8 arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 264 struct mcontext __user *tm_frame,
>> int ctx_has_vsx_region)
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 265 {
>> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 266 unsigned long msr = regs->msr;
>> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 267
>> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 268 /* save general registers */
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 269 unsafe_save_general_regs(regs, frame, failed);
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 270
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 271 #ifdef CONFIG_ALTIVEC
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 272 /* save altivec registers */
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 273 if (current->thread.used_vr) {
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 274 unsafe_copy_to_user(&frame->mc_vregs,
>> ¤t->thread.vr_state,
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 275 ELF_NVRREG * sizeof(vector128),
>> failed);
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 276 /* set MSR_VEC in the saved MSR value to
>> indicate that
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 277 frame->mc_vregs contains valid data */
>> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 278 msr |= MSR_VEC;
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 279 }
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 280 /* else assert((regs->msr & MSR_VEC) == 0) */
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 281
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 282 /* We always copy to/from vrsave, it's 0 if we
>> don't have or don't
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 283 * use altivec. Since VSCR only contains 32 bits
>> saved in the least
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 284 * significant bits of a vector, we "cheat" and
>> stuff VRSAVE in the
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 285 * most significant bits of that same vector. --BenH
>> 408a7e08b2112f arch/powerpc/kernel/signal_32.c Paul Mackerras
>> 2013-08-05 286 * Note that the current VRSAVE value is in the
>> SPR at this point.
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 287 */
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 288 unsafe_put_user(current->thread.vrsave, (u32
>> __user *)&frame->mc_vregs[32],
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 289 failed);
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 290 #endif /* CONFIG_ALTIVEC */
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 291 unsafe_copy_fpr_to_user(&frame->mc_fregs,
>> current, failed);
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 292
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 293 /*
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 294 * Clear the MSR VSX bit to indicate there is no
>> valid state attached
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 295 * to this context, except in the specific case
>> below where we set it.
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 296 */
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 @297 msr &= ~MSR_VSX;
>> 6a274c08f2f4df arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-07-02 298 #ifdef CONFIG_VSX
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 299 /*
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 300 * Copy VSR 0-31 upper half from thread_struct to
>> local
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 301 * buffer, then write that to userspace. Also
>> set MSR_VSX in
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 302 * the saved MSR value to indicate that
>> frame->mc_vregs
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 303 * contains valid data
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 304 */
>> 16c29d180becc5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-10-23 305 if (current->thread.used_vsr &&
>> ctx_has_vsx_region) {
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 306 unsafe_copy_vsx_to_user(&frame->mc_vsregs,
>> current, failed);
>> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 307 msr |= MSR_VSX;
>> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-11-25 308 }
>> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 309 #endif /* CONFIG_VSX */
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 310 #ifdef CONFIG_SPE
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 311 /* save spe registers */
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 312 if (current->thread.used_spe) {
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 313 unsafe_copy_to_user(&frame->mc_vregs,
>> current->thread.evr,
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 314 ELF_NEVRREG * sizeof(u32), failed);
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 315 /* set MSR_SPE in the saved MSR value to
>> indicate that
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 316 frame->mc_vregs contains valid data */
>> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2008-06-25 317 msr |= MSR_SPE;
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 318 }
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 319 /* else assert((regs->msr & MSR_SPE) == 0) */
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 320
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 321 /* We always copy to/from spefscr */
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 322 unsafe_put_user(current->thread.spefscr,
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 323 (u32 __user *)&frame->mc_vregs +
>> ELF_NEVRREG, failed);
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 324 #endif /* CONFIG_SPE */
>> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell
>> 2005-10-18 325
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR],
>> failed);
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 327
>> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-06-09 328 /* We need to write 0 the MSR top 32 bits in the
>> tm frame so that we
>> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-06-09 329 * can check it on the restore to see if TM is
>> active
>> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-06-09 330 */
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 331 if (tm_frame)
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 332 unsafe_put_user(0,
>> &tm_frame->mc_gregs[PT_MSR], failed);
>> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling
>> 2013-06-09 333
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 334 return 0;
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 335
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 336 failed:
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>> 2020-08-18 337 return 1;
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 338 }
>> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds
>> 2005-04-16 339
>>
>> :::::: The code at line 297 was first introduced by commit
>> :::::: ec67ad82814bee92251fd963bf01c7a173856555 powerpc/signals:
>> Improved mark VSX not saved with small contexts fix
>>
>> :::::: TO: Michael Neuling <mikey@neuling.org>
>> :::::: CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>>
> _______________________________________________
> kbuild-all mailing list -- kbuild-all@lists.01.org
> To unsubscribe send an email to kbuild-all-leave@lists.01.org
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [kbuild-all] Re: arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
2021-08-24 6:59 ` [kbuild-all] " Chen, Rong A
@ 2021-08-24 7:29 ` Christophe Leroy
2021-08-25 8:48 ` Rong Chen
0 siblings, 1 reply; 5+ messages in thread
From: Christophe Leroy @ 2021-08-24 7:29 UTC (permalink / raw)
To: Chen, Rong A, kernel test robot
Cc: clang-built-linux, kbuild-all, linux-kernel, Michael Ellerman
Le 24/08/2021 à 08:59, Chen, Rong A a écrit :
>
>
> On 8/23/2021 10:35 PM, Christophe Leroy wrote:
>>
>>
>> Le 23/08/2021 à 12:59, kernel test robot a écrit :
>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>> head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93
>>> commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32: Transform save_user_regs() and
>>> save_tm_user_regs() in 'unsafe' version
>>> date: 9 months ago
>>> config: powerpc-randconfig-c003-20210821 (attached as .config)
>>> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
>>> d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa)
>>> 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
>>> # install powerpc cross compiling tool for clang build
>>> # apt-get install binutils-powerpc-linux-gnu
>>> #
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc
>>>
>>> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>> git fetch --no-tags linus master
>>> git checkout ef75e73182949a94bde169a774de1b62ae21fbbc
>>> # save the attached .config to linux build tree
>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc clang-analyzer
>>>
>>> If you fix the issue, kindly add following tag as appropriate
>>> Reported-by: kernel test robot <lkp@intel.com>
>>>
>>>
>>> clang-analyzer warnings: (new ones prefixed by >>)
>>> ^
>>>>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read
>>>>> [clang-analyzer-deadcode.DeadStores]
>>> msr &= ~MSR_VSX;
>>> ^ ~~~~~~~~
>>> arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to 'msr' is never read
>>> msr &= ~MSR_VSX;
>>> ^ ~~~~~~~~
>>
>>
>> This is wrong.
>>
>> msr is used at line 326:
>>
>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy 2020-08-18 326
>> unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
>
> Hi Christophe,
>
> The usage is under CONFIG_VSX, the test config (powerpc-randconfig-c003-20210821) didn't enable it
> which triggered this warning.
No no, the 'unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed) ' at line 326 is not under
CONFIG_VSX as far as I can see.
Christophe
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [kbuild-all] Re: arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores]
2021-08-24 7:29 ` Christophe Leroy
@ 2021-08-25 8:48 ` Rong Chen
0 siblings, 0 replies; 5+ messages in thread
From: Rong Chen @ 2021-08-25 8:48 UTC (permalink / raw)
To: Christophe Leroy, kernel test robot
Cc: clang-built-linux, kbuild-all, linux-kernel, Michael Ellerman
On 8/24/21 3:29 PM, Christophe Leroy wrote:
>
>
> Le 24/08/2021 à 08:59, Chen, Rong A a écrit :
>>
>>
>> On 8/23/2021 10:35 PM, Christophe Leroy wrote:
>>>
>>>
>>> Le 23/08/2021 à 12:59, kernel test robot a écrit :
>>>> tree:
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>>> master
>>>> head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93
>>>> commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32:
>>>> Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version
>>>> date: 9 months ago
>>>> config: powerpc-randconfig-c003-20210821 (attached as .config)
>>>> compiler: clang version 14.0.0
>>>> (https://github.com/llvm/llvm-project
>>>> d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa)
>>>> 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
>>>> # install powerpc cross compiling tool for clang build
>>>> # apt-get install binutils-powerpc-linux-gnu
>>>> #
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc
>>>>
>>>> git remote add linus
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>>> git fetch --no-tags linus master
>>>> git checkout ef75e73182949a94bde169a774de1b62ae21fbbc
>>>> # save the attached .config to linux build tree
>>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross
>>>> ARCH=powerpc clang-analyzer
>>>>
>>>> If you fix the issue, kindly add following tag as appropriate
>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>
>>>>
>>>> clang-analyzer warnings: (new ones prefixed by >>)
>>>> ^
>>>>>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to
>>>>>> 'msr' is never read [clang-analyzer-deadcode.DeadStores]
>>>> msr &= ~MSR_VSX;
>>>> ^ ~~~~~~~~
>>>> arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to
>>>> 'msr' is never read
>>>> msr &= ~MSR_VSX;
>>>> ^ ~~~~~~~~
>>>
>>>
>>> This is wrong.
>>>
>>> msr is used at line 326:
>>>
>>> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy
>>> 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
>>
>> Hi Christophe,
>>
>> The usage is under CONFIG_VSX, the test config
>> (powerpc-randconfig-c003-20210821) didn't enable it which triggered
>> this warning.
>
>
> No no, the 'unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed) '
> at line 326 is not under CONFIG_VSX as far as I can see.
>
>
> Christophe
Hi Christophe,
It's my fault, I didn't see it correctly, and I have no idea why
clang-analyzer reported it as a issue,
we'll double check such warning next time.
Best Regards,
Rong Chen
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-08-25 8:48 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-08-23 14:35 ` Christophe Leroy
2021-08-24 6:59 ` [kbuild-all] " Chen, Rong A
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