| Message ID | 20160516201618.u4zethkab3ohgtfb@treble (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
On Mon, 2016-05-16 at 15:16 -0500, Josh Poimboeuf wrote: > On Mon, May 16, 2016 at 11:31:12AM -0700, Megha Dey wrote: > > On Mon, 2016-05-16 at 09:44 -0500, Josh Poimboeuf wrote: > > > On Fri, May 13, 2016 at 10:32:26AM -0700, Megha Dey wrote: > > > > On Fri, 2016-05-13 at 07:51 +0200, Ingo Molnar wrote: > > > > > * Herbert Xu <herbert@gondor.apana.org.au> wrote: > > > > > > > > > > > On Thu, May 12, 2016 at 04:31:06PM -0700, Megha Dey wrote: > > > > > > > Hi, > > > > > > > > > > > > > > When booting latest kernel with the CONFIG_CRYPTO_SHA1_MB enabled, I > > > > > > > observe a panic. > > > > > > > > > > > > > > After having a quick look, on reverting the following patches, I am able > > > > > > > to complete the booting process. > > > > > > > aec4d0e301f17bb143341c82cc44685b8af0b945 > > > > > > > 8691ccd764f9ecc69a6812dfe76214c86ac9ba06 > > > > > > > 68874ac3304ade7ed5ebb12af00d6b9bbbca0a16 > > > > > > > > > > > > > > Of the 3 patches, aec4d0e301f17bb143341c82cc44685b8af0b945 seems wrong. > > > > > > > The r10 to r15 registers are used in sha1_x8_avx2.S, which is called > > > > > > > from sha1_mb_mgr_flush_avx2.S. > > > > > > > > > > > > > > I do not think the functionality of the SHA1-MB crypto algorithm has > > > > > > > been tested after applying these changes. (I am not sure if any of the > > > > > > > other crypto algorithms have been affected by these changes). > > > > > > > > > > > > Josh, Ingo: > > > > > > > > > > > > Any ideas on this? Should we revert? > > > > > > > > > > Yeah, I think so - although another option would be to standardize sha1_x8_avx2() > > > > > - the problem is that it is a function that clobbers registers without > > > > > saving/restoring them, breaking the C function ABI. I realize it's written in > > > > > assembly, but unless there are strong performance reasons to deviate from the > > > > > regular calling convention it might make sense to fix that. > > > > > > > > > > Do any warnings get generated after the revert, if you enable > > > > > CONFIG_STACK_VALIDATION=y? > > > > > > > > After the revert and enabling CONFIG_STACK_VALIDATION: > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_flush_avx2.o: warning: objtool: > > > > sha1_mb_mgr_flush_avx2()+0x20d: call without frame pointer save/setup > > > > > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_submit_avx2.o: warning: objtool: > > > > sha1_mb_mgr_submit_avx2()+0x115: call without frame pointer save/setup > > > > > > Megha, > > > > > > Sorry for breaking it. I completely missed the fact that the function > > > calls sha1_x8_avx2() which clobbers registers. > > > > > > If the performance penalty isn't too bad, I'll submit a patch to > > > standardize sha1_x8_avx2() to follow the C ABI. > > > > > > Do you have any tips for testing this code? I've tried using the tcrypt > > > module, but no luck. > > > > > Josh, > > Build the kernel with the following configs: > > CONFIG_CRYPTO_SHA1_MB=y > > CONFIG_CRYPTO_TEST=m > > CONFIG_CRYPTO_MANAGER_DISABLE_TESTS=n > > There was a kernel panic while booting. > > So if after applying your new patch, we are able to get complete the > > boot, then we are good. > > > > Could you please send a copy of the patch, I could test it on my end > > too. > > Thanks. I was able to run the tests, though I didn't see a panic. Can > you test with this patch? > > ---- > > From: Josh Poimboeuf <jpoimboe@redhat.com> > Subject: [PATCH] crypto/sha1-mb: make sha1_x8_avx2() conform to C function ABI > > Megha Day reported a kernel panic in crypto code. The problem is that > sha1_x8_avx2() clobbers registers r12-r15 without saving and restoring > them. > > Before commit aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in > sha-mb functions"), those registers were saved and restored by the > callers of the function. I removed them with that commit because I > didn't realize sha1_x8_avx2() clobbered them. > > Fix the potential undefined behavior associated with clobbering the > registers and make the behavior less surprising by changing the > registers to be callee saved/restored to conform with the C function > call ABI. > > Also, rdx (aka RSP_SAVE) doesn't need to be saved: I verified that none > of the callers rely on it being saved, and it's not a callee-saved > register in the C ABI. > > Fixes: aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in sha-mb functions") > Cc: stable@vger.kernel.org # 4.6 > Reported-by: Megha Dey <megha.dey@linux.intel.com> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > index 8e1b477..c9dae1c 100644 > --- a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > +++ b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > @@ -296,7 +296,11 @@ W14 = TMP_ > # > ENTRY(sha1_x8_avx2) > > - push RSP_SAVE > + # save callee-saved clobbered registers to comply with C function ABI > + push %r12 > + push %r13 > + push %r14 > + push %r15 > > #save rsp > mov %rsp, RSP_SAVE > @@ -446,7 +450,12 @@ lloop: > ## Postamble > > mov RSP_SAVE, %rsp > - pop RSP_SAVE > + > + # restore callee-saved clobbered registers > + pop %r15 > + pop %r14 > + pop %r13 > + pop %r12 > > ret > ENDPROC(sha1_x8_avx2) Hi Josh, I don't see the panic and am able to boot. However, I am not able to see the tests running. You said you were able to insert the tcrypt module and test this right? -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, May 16, 2016 at 02:39:06PM -0700, Megha Dey wrote: > On Mon, 2016-05-16 at 15:16 -0500, Josh Poimboeuf wrote: > > On Mon, May 16, 2016 at 11:31:12AM -0700, Megha Dey wrote: > > > On Mon, 2016-05-16 at 09:44 -0500, Josh Poimboeuf wrote: > > > > On Fri, May 13, 2016 at 10:32:26AM -0700, Megha Dey wrote: > > > > > On Fri, 2016-05-13 at 07:51 +0200, Ingo Molnar wrote: > > > > > > * Herbert Xu <herbert@gondor.apana.org.au> wrote: > > > > > > > > > > > > > On Thu, May 12, 2016 at 04:31:06PM -0700, Megha Dey wrote: > > > > > > > > Hi, > > > > > > > > > > > > > > > > When booting latest kernel with the CONFIG_CRYPTO_SHA1_MB enabled, I > > > > > > > > observe a panic. > > > > > > > > > > > > > > > > After having a quick look, on reverting the following patches, I am able > > > > > > > > to complete the booting process. > > > > > > > > aec4d0e301f17bb143341c82cc44685b8af0b945 > > > > > > > > 8691ccd764f9ecc69a6812dfe76214c86ac9ba06 > > > > > > > > 68874ac3304ade7ed5ebb12af00d6b9bbbca0a16 > > > > > > > > > > > > > > > > Of the 3 patches, aec4d0e301f17bb143341c82cc44685b8af0b945 seems wrong. > > > > > > > > The r10 to r15 registers are used in sha1_x8_avx2.S, which is called > > > > > > > > from sha1_mb_mgr_flush_avx2.S. > > > > > > > > > > > > > > > > I do not think the functionality of the SHA1-MB crypto algorithm has > > > > > > > > been tested after applying these changes. (I am not sure if any of the > > > > > > > > other crypto algorithms have been affected by these changes). > > > > > > > > > > > > > > Josh, Ingo: > > > > > > > > > > > > > > Any ideas on this? Should we revert? > > > > > > > > > > > > Yeah, I think so - although another option would be to standardize sha1_x8_avx2() > > > > > > - the problem is that it is a function that clobbers registers without > > > > > > saving/restoring them, breaking the C function ABI. I realize it's written in > > > > > > assembly, but unless there are strong performance reasons to deviate from the > > > > > > regular calling convention it might make sense to fix that. > > > > > > > > > > > > Do any warnings get generated after the revert, if you enable > > > > > > CONFIG_STACK_VALIDATION=y? > > > > > > > > > > After the revert and enabling CONFIG_STACK_VALIDATION: > > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_flush_avx2.o: warning: objtool: > > > > > sha1_mb_mgr_flush_avx2()+0x20d: call without frame pointer save/setup > > > > > > > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_submit_avx2.o: warning: objtool: > > > > > sha1_mb_mgr_submit_avx2()+0x115: call without frame pointer save/setup > > > > > > > > Megha, > > > > > > > > Sorry for breaking it. I completely missed the fact that the function > > > > calls sha1_x8_avx2() which clobbers registers. > > > > > > > > If the performance penalty isn't too bad, I'll submit a patch to > > > > standardize sha1_x8_avx2() to follow the C ABI. > > > > > > > > Do you have any tips for testing this code? I've tried using the tcrypt > > > > module, but no luck. > > > > > > > Josh, > > > Build the kernel with the following configs: > > > CONFIG_CRYPTO_SHA1_MB=y > > > CONFIG_CRYPTO_TEST=m > > > CONFIG_CRYPTO_MANAGER_DISABLE_TESTS=n > > > There was a kernel panic while booting. > > > So if after applying your new patch, we are able to get complete the > > > boot, then we are good. > > > > > > Could you please send a copy of the patch, I could test it on my end > > > too. > > > > Thanks. I was able to run the tests, though I didn't see a panic. Can > > you test with this patch? > > > > ---- > > > > From: Josh Poimboeuf <jpoimboe@redhat.com> > > Subject: [PATCH] crypto/sha1-mb: make sha1_x8_avx2() conform to C function ABI > > > > Megha Day reported a kernel panic in crypto code. The problem is that > > sha1_x8_avx2() clobbers registers r12-r15 without saving and restoring > > them. > > > > Before commit aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in > > sha-mb functions"), those registers were saved and restored by the > > callers of the function. I removed them with that commit because I > > didn't realize sha1_x8_avx2() clobbered them. > > > > Fix the potential undefined behavior associated with clobbering the > > registers and make the behavior less surprising by changing the > > registers to be callee saved/restored to conform with the C function > > call ABI. > > > > Also, rdx (aka RSP_SAVE) doesn't need to be saved: I verified that none > > of the callers rely on it being saved, and it's not a callee-saved > > register in the C ABI. > > > > Fixes: aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in sha-mb functions") > > Cc: stable@vger.kernel.org # 4.6 > > Reported-by: Megha Dey <megha.dey@linux.intel.com> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > --- > > arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 13 +++++++++++-- > > 1 file changed, 11 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > index 8e1b477..c9dae1c 100644 > > --- a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > +++ b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > @@ -296,7 +296,11 @@ W14 = TMP_ > > # > > ENTRY(sha1_x8_avx2) > > > > - push RSP_SAVE > > + # save callee-saved clobbered registers to comply with C function ABI > > + push %r12 > > + push %r13 > > + push %r14 > > + push %r15 > > > > #save rsp > > mov %rsp, RSP_SAVE > > @@ -446,7 +450,12 @@ lloop: > > ## Postamble > > > > mov RSP_SAVE, %rsp > > - pop RSP_SAVE > > + > > + # restore callee-saved clobbered registers > > + pop %r15 > > + pop %r14 > > + pop %r13 > > + pop %r12 > > > > ret > > ENDPROC(sha1_x8_avx2) > > Hi Josh, > I don't see the panic and am able to boot. However, I am not able to see > the tests running. You said you were able to insert the tcrypt module > and test this right? I didn't insert tcrypt manually, but I set the config flags you suggested, plus I added a few printks, and was at least able to verify that this code ran during boot without any crypto test errors or other warnings being reported.
On Mon, 2016-05-16 at 16:46 -0500, Josh Poimboeuf wrote: > On Mon, May 16, 2016 at 02:39:06PM -0700, Megha Dey wrote: > > On Mon, 2016-05-16 at 15:16 -0500, Josh Poimboeuf wrote: > > > On Mon, May 16, 2016 at 11:31:12AM -0700, Megha Dey wrote: > > > > On Mon, 2016-05-16 at 09:44 -0500, Josh Poimboeuf wrote: > > > > > On Fri, May 13, 2016 at 10:32:26AM -0700, Megha Dey wrote: > > > > > > On Fri, 2016-05-13 at 07:51 +0200, Ingo Molnar wrote: > > > > > > > * Herbert Xu <herbert@gondor.apana.org.au> wrote: > > > > > > > > > > > > > > > On Thu, May 12, 2016 at 04:31:06PM -0700, Megha Dey wrote: > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > When booting latest kernel with the CONFIG_CRYPTO_SHA1_MB enabled, I > > > > > > > > > observe a panic. > > > > > > > > > > > > > > > > > > After having a quick look, on reverting the following patches, I am able > > > > > > > > > to complete the booting process. > > > > > > > > > aec4d0e301f17bb143341c82cc44685b8af0b945 > > > > > > > > > 8691ccd764f9ecc69a6812dfe76214c86ac9ba06 > > > > > > > > > 68874ac3304ade7ed5ebb12af00d6b9bbbca0a16 > > > > > > > > > > > > > > > > > > Of the 3 patches, aec4d0e301f17bb143341c82cc44685b8af0b945 seems wrong. > > > > > > > > > The r10 to r15 registers are used in sha1_x8_avx2.S, which is called > > > > > > > > > from sha1_mb_mgr_flush_avx2.S. > > > > > > > > > > > > > > > > > > I do not think the functionality of the SHA1-MB crypto algorithm has > > > > > > > > > been tested after applying these changes. (I am not sure if any of the > > > > > > > > > other crypto algorithms have been affected by these changes). > > > > > > > > > > > > > > > > Josh, Ingo: > > > > > > > > > > > > > > > > Any ideas on this? Should we revert? > > > > > > > > > > > > > > Yeah, I think so - although another option would be to standardize sha1_x8_avx2() > > > > > > > - the problem is that it is a function that clobbers registers without > > > > > > > saving/restoring them, breaking the C function ABI. I realize it's written in > > > > > > > assembly, but unless there are strong performance reasons to deviate from the > > > > > > > regular calling convention it might make sense to fix that. > > > > > > > > > > > > > > Do any warnings get generated after the revert, if you enable > > > > > > > CONFIG_STACK_VALIDATION=y? > > > > > > > > > > > > After the revert and enabling CONFIG_STACK_VALIDATION: > > > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_flush_avx2.o: warning: objtool: > > > > > > sha1_mb_mgr_flush_avx2()+0x20d: call without frame pointer save/setup > > > > > > > > > > > > arch/x86/crypto/sha1-mb/sha1_mb_mgr_submit_avx2.o: warning: objtool: > > > > > > sha1_mb_mgr_submit_avx2()+0x115: call without frame pointer save/setup > > > > > > > > > > Megha, > > > > > > > > > > Sorry for breaking it. I completely missed the fact that the function > > > > > calls sha1_x8_avx2() which clobbers registers. > > > > > > > > > > If the performance penalty isn't too bad, I'll submit a patch to > > > > > standardize sha1_x8_avx2() to follow the C ABI. > > > > > > > > > > Do you have any tips for testing this code? I've tried using the tcrypt > > > > > module, but no luck. > > > > > > > > > Josh, > > > > Build the kernel with the following configs: > > > > CONFIG_CRYPTO_SHA1_MB=y > > > > CONFIG_CRYPTO_TEST=m > > > > CONFIG_CRYPTO_MANAGER_DISABLE_TESTS=n > > > > There was a kernel panic while booting. > > > > So if after applying your new patch, we are able to get complete the > > > > boot, then we are good. > > > > > > > > Could you please send a copy of the patch, I could test it on my end > > > > too. > > > > > > Thanks. I was able to run the tests, though I didn't see a panic. Can > > > you test with this patch? > > > > > > ---- > > > > > > From: Josh Poimboeuf <jpoimboe@redhat.com> > > > Subject: [PATCH] crypto/sha1-mb: make sha1_x8_avx2() conform to C function ABI > > > > > > Megha Day reported a kernel panic in crypto code. The problem is that > > > sha1_x8_avx2() clobbers registers r12-r15 without saving and restoring > > > them. > > > > > > Before commit aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in > > > sha-mb functions"), those registers were saved and restored by the > > > callers of the function. I removed them with that commit because I > > > didn't realize sha1_x8_avx2() clobbered them. > > > > > > Fix the potential undefined behavior associated with clobbering the > > > registers and make the behavior less surprising by changing the > > > registers to be callee saved/restored to conform with the C function > > > call ABI. > > > > > > Also, rdx (aka RSP_SAVE) doesn't need to be saved: I verified that none > > > of the callers rely on it being saved, and it's not a callee-saved > > > register in the C ABI. > > > > > > Fixes: aec4d0e301f1 ("x86/asm/crypto: Simplify stack usage in sha-mb functions") > > > Cc: stable@vger.kernel.org # 4.6 > > > Reported-by: Megha Dey <megha.dey@linux.intel.com> > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > > --- > > > arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 13 +++++++++++-- > > > 1 file changed, 11 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > > index 8e1b477..c9dae1c 100644 > > > --- a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > > +++ b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S > > > @@ -296,7 +296,11 @@ W14 = TMP_ > > > # > > > ENTRY(sha1_x8_avx2) > > > > > > - push RSP_SAVE > > > + # save callee-saved clobbered registers to comply with C function ABI > > > + push %r12 > > > + push %r13 > > > + push %r14 > > > + push %r15 > > > > > > #save rsp > > > mov %rsp, RSP_SAVE > > > @@ -446,7 +450,12 @@ lloop: > > > ## Postamble > > > > > > mov RSP_SAVE, %rsp > > > - pop RSP_SAVE > > > + > > > + # restore callee-saved clobbered registers > > > + pop %r15 > > > + pop %r14 > > > + pop %r13 > > > + pop %r12 > > > > > > ret > > > ENDPROC(sha1_x8_avx2) > > > > Hi Josh, > > I don't see the panic and am able to boot. However, I am not able to see > > the tests running. You said you were able to insert the tcrypt module > > and test this right? > > I didn't insert tcrypt manually, but I set the config flags you > suggested, plus I added a few printks, and was at least able to verify > that this code ran during boot without any crypto test errors or other > warnings being reported. > ok. I tried at my end too using some printk's and nothing seems to be broken. Also, if you intend to use the same commit message, I spell my name as Megha Dey and not Day :) -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, May 16, 2016 at 04:07:53PM -0700, Megha Dey wrote: > > ok. I tried at my end too using some printk's and nothing seems to be > broken. Also, if you intend to use the same commit message, I spell my > name as Megha Dey and not Day :) Patch applied with the name corrected. Thanks,
diff --git a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S index 8e1b477..c9dae1c 100644 --- a/arch/x86/crypto/sha-mb/sha1_x8_avx2.S +++ b/arch/x86/crypto/sha-mb/sha1_x8_avx2.S @@ -296,7 +296,11 @@ W14 = TMP_ # ENTRY(sha1_x8_avx2) - push RSP_SAVE + # save callee-saved clobbered registers to comply with C function ABI + push %r12 + push %r13 + push %r14 + push %r15 #save rsp mov %rsp, RSP_SAVE @@ -446,7 +450,12 @@ lloop: ## Postamble mov RSP_SAVE, %rsp - pop RSP_SAVE + + # restore callee-saved clobbered registers + pop %r15 + pop %r14 + pop %r13 + pop %r12 ret ENDPROC(sha1_x8_avx2)