| Message ID | 20190802170300.20662-7-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add arm64/signal initial kselftest support | expand |
On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: > Added a simple fake_sigreturn testcase which builds a ucontext_t Add > with a bad magic header and place it onto the stack. > Expects a SIGSEGV on test PASS. > This commit also introduces a common utility assembly function to > invoke a sigreturn using a fake provided sigframe. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> > --- > tools/testing/selftests/arm64/signal/Makefile | 2 +- > .../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++ > .../arm64/signal/test_signals_utils.h | 1 + > .../arm64/signal/testcases/.gitignore | 1 + > .../testcases/fake_sigreturn_bad_magic.c | 63 ++++++++++++++++++ > 5 files changed, 130 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/arm64/signal/signals.S > create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > > diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile > index 8c8d08be4b0d..b3dcf315b5a4 100644 > --- a/tools/testing/selftests/arm64/signal/Makefile > +++ b/tools/testing/selftests/arm64/signal/Makefile > @@ -80,7 +80,7 @@ endif > # Common test-unit targets to build common-layout test-cases executables > # Needs secondary expansion to properly include the testcase c-file in pre-reqs > .SECONDEXPANSION: > -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h > +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h > @if [ ! -d $(khdr_dir) ]; then \ > echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ > echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ > diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S > new file mode 100644 > index 000000000000..6262b877400b > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/signals.S > @@ -0,0 +1,64 @@ > +/* > + * SPDX-License-Identifier: GPL-2.0 > + * Copyright (C) 2019 ARM Limited > + */ > + > +#include <asm/unistd.h> > + > +.section ".rodata", "a" The section name is not usually quoted in .section (though I guess it works). > +call_fmt: > + .asciz "Calling sigreturn with fake sigframe sized:%zd at calculated SP @%08lX\n" > + > +.text > + > +.globl fake_sigreturn > + > +/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:alignment_SP */ > +fake_sigreturn: > + mov x20, x0 > + mov x21, x1 > + mov x22, x2 > + mov x23, sp > + > + /* create space on the stack for fake sigframe..."x22"-aligned */ > + mov x0, #0 Why to we move 0 into x0? We clobber x0 again in the next instruction: > + add x0, x21, x22 > + sub x22, x22, #1 > + bic x0, x0, x22 > + sub x23, x23, x0 Can you explain the logic here? I'm not sure I understand what this is trying to do exactly. I notice you further modify this in patch 11 -- see my comments there, where I also suggest an alternative way of specifying a misaligned frame that might be simpler. > + > + ldr x0, =call_fmt > + mov x1, x21 > + mov x2, x23 > + bl printf > + > + mov sp, x23 > + > + /* now fill it with the provided content... */ > + mov x0, sp > + mov x1, x20 > + mov x2, x21 > + bl memcpy > + > + /* > + * Here saving a last minute SP to current->token acts as a marker: > + * if we got here, we are successfully faking a sigreturn; in other > + * words we are sure no bad fatal signal has been raised till now > + * for unrelated reasons, so we should consider the possibl observed typo: possible (or possibly?) > + * fatal signal like SEGV coming from Kernel restore_sigframe() and > + * triggered as expected from our test-case. > + * For simplicity this assumes that current field 'token' is laid out > + * as first in struct tdescr > + */ > + ldr x0, current > + str x23, [x0] > + /* SP is already pointing back to the just built fake sigframe here */ > + mov x8, #__NR_rt_sigreturn > + svc #0 > + > + /* > + * Above sigreturn should not return...looping here leads to a timeout > + * and ensure proper and clean test failure, instead of jumping around > + * on a potentially corrupted stack. > + */ > + b . > diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h > index ce35be8ebc8e..2a71da7e6695 100644 > --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h > +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h > @@ -12,4 +12,5 @@ int test_run(struct tdescr *td); > void test_result(struct tdescr *td); > > bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); > +int fake_sigreturn(void *sigframe, size_t sz, int alignment); > #endif > diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore > index a48a118b1a1a..0ea6fdc3765c 100644 > --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore > +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore > @@ -4,3 +4,4 @@ mangle_pstate_invalid_mode_el1 > mangle_pstate_invalid_mode_el2 > mangle_pstate_invalid_mode_el3 > mangle_pstate_ssbs_regs > +fake_sigreturn_bad_magic > diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > new file mode 100644 > index 000000000000..b4c063e02a7a > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > @@ -0,0 +1,63 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* Copyright (C) 2019 ARM Limited */ > + We should probably also include <signal.h> here, since we're using siginfo_t etc. > +#include <stdio.h> > +#include <ucontext.h> > + > +#include "test_signals_utils.h" > +#include "testcases.h" > + > +struct fake_sigframe sf; > + > +static int fake_sigreturn_bad_magic_run(struct tdescr *td, > + siginfo_t *si, ucontext_t *uc) > +{ > + size_t resv_sz, offset; > + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; > + > + /* just to fill the ucontext_t with something real */ > + if (!get_current_context(td, &sf.uc)) > + return 1; > + > + resv_sz = GET_SF_RESV_SIZE(sf); > + /* > + * find the terminator, preserving existing headers > + * and verify amount of spare room in __reserved area. > + */ > + head = get_terminator(shead, resv_sz, &offset); > + /* > + * try stripping extra_context header when low on space: > + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC > + * and the other for the usual terminator. > + */ > + if (head && resv_sz - offset < HDR_SZ * 2) { Can we factor out this logic for finding space in the signal frame? We do pretty much the same thing in all the fake_sigreturn tests... > + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", > + resv_sz - offset); > + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); > + } > + /* just give up and timeout if still not enough space */ Do we actually time out? I don't see where we actually wait, so doesn't test_run() just fail immediately? The same applies to all the other fake_sigreturn tests too. > + if (head && resv_sz - offset >= HDR_SZ) { Should this be HDR_SZ * 2 again? We need space for the face header and space to write a terminator after it. > + fprintf(stderr, "Mangling template header. Spare space:%zd\n", > + resv_sz - offset); > + /* > + * use a well known NON existent bad magic...something > + * we should pretty sure won't be ever defined in Kernel > + */ > + head->magic = KSFT_BAD_MAGIC; > + head->size = HDR_SZ; > + write_terminator_record(GET_RESV_NEXT_HEAD(head)); > + > + ASSERT_BAD_CONTEXT(&sf.uc); > + fake_sigreturn(&sf, sizeof(sf), 16); > + } > + > + return 1; > +} [...] Cheers ---Dave
Hi On 13/08/2019 17:25, Dave Martin wrote: > On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: >> Added a simple fake_sigreturn testcase which builds a ucontext_t > > Add Ok > >> with a bad magic header and place it onto the stack. >> Expects a SIGSEGV on test PASS. >> This commit also introduces a common utility assembly function to >> invoke a sigreturn using a fake provided sigframe. >> >> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> >> --- >> tools/testing/selftests/arm64/signal/Makefile | 2 +- >> .../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++ >> .../arm64/signal/test_signals_utils.h | 1 + >> .../arm64/signal/testcases/.gitignore | 1 + >> .../testcases/fake_sigreturn_bad_magic.c | 63 ++++++++++++++++++ >> 5 files changed, 130 insertions(+), 1 deletion(-) >> create mode 100644 tools/testing/selftests/arm64/signal/signals.S >> create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c >> >> diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile >> index 8c8d08be4b0d..b3dcf315b5a4 100644 >> --- a/tools/testing/selftests/arm64/signal/Makefile >> +++ b/tools/testing/selftests/arm64/signal/Makefile >> @@ -80,7 +80,7 @@ endif >> # Common test-unit targets to build common-layout test-cases executables >> # Needs secondary expansion to properly include the testcase c-file in pre-reqs >> .SECONDEXPANSION: >> -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h >> +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h >> @if [ ! -d $(khdr_dir) ]; then \ >> echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ >> echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ >> diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S >> new file mode 100644 >> index 000000000000..6262b877400b >> --- /dev/null >> +++ b/tools/testing/selftests/arm64/signal/signals.S >> @@ -0,0 +1,64 @@ >> +/* >> + * SPDX-License-Identifier: GPL-2.0 >> + * Copyright (C) 2019 ARM Limited >> + */ >> + >> +#include <asm/unistd.h> >> + >> +.section ".rodata", "a" > > The section name is not usually quoted in .section (though I guess it > works). > Ok >> +call_fmt: >> + .asciz "Calling sigreturn with fake sigframe sized:%zd at calculated SP @%08lX\n" >> + >> +.text >> + >> +.globl fake_sigreturn >> + >> +/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:alignment_SP */ >> +fake_sigreturn: >> + mov x20, x0 >> + mov x21, x1 >> + mov x22, x2 >> + mov x23, sp >> + >> + /* create space on the stack for fake sigframe..."x22"-aligned */ >> + mov x0, #0 > > Why to we move 0 into x0? We clobber x0 again in the next instruction: Yes unneeded. >> + add x0, x21, x22 >> + sub x22, x22, #1 >> + bic x0, x0, x22 >> + sub x23, x23, x0 > > Can you explain the logic here? I'm not sure I understand what this is > trying to do exactly. The attempt is to make space on the stack for a x22-bytes-aligned sigframe of at least x21-bytes-size (assuming x22 is power-of-two): - calculate the needed aligned space (sigframe_size + x22) & ~(x22 - 1) - calculate new SP in x23: x3 = sp - needed_aligned_space - later down... move SP to the calculated sp in x23 - copy the provided sigframe on such new SP > I notice you further modify this in patch 11 -- see my comments there, > where I also suggest an alternative way of specifying a misaligned frame > that might be simpler. I've seen your comments on patch 11. I think I'll simplify that as you suggested: patch 11 was meant to add the capability to misalign the sigframe on the SP (which is needed in testcase contained in 11) but in fact is better if I move all of the simplified logic here. >> + >> + ldr x0, =call_fmt >> + mov x1, x21 >> + mov x2, x23 >> + bl printf >> + >> + mov sp, x23 >> + >> + /* now fill it with the provided content... */ >> + mov x0, sp >> + mov x1, x20 >> + mov x2, x21 >> + bl memcpy >> + >> + /* >> + * Here saving a last minute SP to current->token acts as a marker: >> + * if we got here, we are successfully faking a sigreturn; in other >> + * words we are sure no bad fatal signal has been raised till now >> + * for unrelated reasons, so we should consider the possibl observed > > typo: possible (or possibly?) > possibly >> + * fatal signal like SEGV coming from Kernel restore_sigframe() and >> + * triggered as expected from our test-case. >> + * For simplicity this assumes that current field 'token' is laid out >> + * as first in struct tdescr >> + */ >> + ldr x0, current >> + str x23, [x0] >> + /* SP is already pointing back to the just built fake sigframe here */ >> + mov x8, #__NR_rt_sigreturn >> + svc #0 >> + >> + /* >> + * Above sigreturn should not return...looping here leads to a timeout >> + * and ensure proper and clean test failure, instead of jumping around >> + * on a potentially corrupted stack. >> + */ >> + b . >> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h >> index ce35be8ebc8e..2a71da7e6695 100644 >> --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h >> +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h >> @@ -12,4 +12,5 @@ int test_run(struct tdescr *td); >> void test_result(struct tdescr *td); >> >> bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); >> +int fake_sigreturn(void *sigframe, size_t sz, int alignment); >> #endif >> diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore >> index a48a118b1a1a..0ea6fdc3765c 100644 >> --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore >> +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore >> @@ -4,3 +4,4 @@ mangle_pstate_invalid_mode_el1 >> mangle_pstate_invalid_mode_el2 >> mangle_pstate_invalid_mode_el3 >> mangle_pstate_ssbs_regs >> +fake_sigreturn_bad_magic >> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c >> new file mode 100644 >> index 000000000000..b4c063e02a7a >> --- /dev/null >> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c >> @@ -0,0 +1,63 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* Copyright (C) 2019 ARM Limited */ >> + > > We should probably also include <signal.h> here, since we're using > siginfo_t etc. Yes indeed. It was included via some other headers only. > >> +#include <stdio.h> >> +#include <ucontext.h> >> + >> +#include "test_signals_utils.h" >> +#include "testcases.h" >> + >> +struct fake_sigframe sf; >> + >> +static int fake_sigreturn_bad_magic_run(struct tdescr *td, >> + siginfo_t *si, ucontext_t *uc) >> +{ >> + size_t resv_sz, offset; >> + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; >> + >> + /* just to fill the ucontext_t with something real */ >> + if (!get_current_context(td, &sf.uc)) >> + return 1; >> + >> + resv_sz = GET_SF_RESV_SIZE(sf); >> + /* >> + * find the terminator, preserving existing headers >> + * and verify amount of spare room in __reserved area. >> + */ >> + head = get_terminator(shead, resv_sz, &offset); >> + /* >> + * try stripping extra_context header when low on space: >> + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC >> + * and the other for the usual terminator. >> + */ >> + if (head && resv_sz - offset < HDR_SZ * 2) { > > Can we factor out this logic for finding space in the signal frame? > > We do pretty much the same thing in all the fake_sigreturn tests... Ok > >> + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", >> + resv_sz - offset); >> + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); >> + } >> + /* just give up and timeout if still not enough space */ > > Do we actually time out? I don't see where we actually wait, so doesn't > test_run() just fail immediately? > > The same applies to all the other fake_sigreturn tests too. > Right. It is probably a leftover. SIGALRM is used as an extreme measure to kill tests gone bad, but this can happen only once the fake sigframe has been effectively placed on the stack and sigreturned. >> + if (head && resv_sz - offset >= HDR_SZ) { > > Should this be HDR_SZ * 2 again? We need space for the face header and > space to write a terminator after it. I'll fix in the new factored out code. > >> + fprintf(stderr, "Mangling template header. Spare space:%zd\n", >> + resv_sz - offset); >> + /* >> + * use a well known NON existent bad magic...something >> + * we should pretty sure won't be ever defined in Kernel >> + */ >> + head->magic = KSFT_BAD_MAGIC; >> + head->size = HDR_SZ; >> + write_terminator_record(GET_RESV_NEXT_HEAD(head)); >> + >> + ASSERT_BAD_CONTEXT(&sf.uc); >> + fake_sigreturn(&sf, sizeof(sf), 16); >> + } >> + >> + return 1; >> +} > > [...] > > Cheers > ---Dave > Cheers Cristian
On Fri, Aug 30, 2019 at 03:29:29PM +0100, Cristian Marussi wrote: > Hi > > On 13/08/2019 17:25, Dave Martin wrote: > > On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: [...] > >> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c [...] > >> +static int fake_sigreturn_bad_magic_run(struct tdescr *td, > >> + siginfo_t *si, ucontext_t *uc) > >> +{ > >> + size_t resv_sz, offset; > >> + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; > >> + > >> + /* just to fill the ucontext_t with something real */ > >> + if (!get_current_context(td, &sf.uc)) > >> + return 1; > >> + > >> + resv_sz = GET_SF_RESV_SIZE(sf); > >> + /* > >> + * find the terminator, preserving existing headers > >> + * and verify amount of spare room in __reserved area. > >> + */ > >> + head = get_terminator(shead, resv_sz, &offset); > >> + /* > >> + * try stripping extra_context header when low on space: > >> + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC > >> + * and the other for the usual terminator. > >> + */ > >> + if (head && resv_sz - offset < HDR_SZ * 2) { > > > > Can we factor out this logic for finding space in the signal frame? > > > > We do pretty much the same thing in all the fake_sigreturn tests... > > Ok > > > >> + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", > >> + resv_sz - offset); > >> + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); > >> + } > >> + /* just give up and timeout if still not enough space */ > > > > Do we actually time out? I don't see where we actually wait, so doesn't > > test_run() just fail immediately? > > > > The same applies to all the other fake_sigreturn tests too. > > > Right. It is probably a leftover. > > SIGALRM is used as an extreme measure to kill tests gone bad, but this > can happen only once the fake sigframe has been effectively placed on the stack > and sigreturned. OK, so this gets reported as a test failure because with no SIGSEGV, nothing ever sets td->pass? This is probably OK for now, though I wonder whether this should be reported as a skipped test instead. In case of doubt, reporting a failure is preferable anyway, since that will encourage people actually to investigate what went wrong. [...] Cheers ---Dave
On 04/09/2019 11:05, Dave Martin wrote: > On Fri, Aug 30, 2019 at 03:29:29PM +0100, Cristian Marussi wrote: >> Hi >> >> On 13/08/2019 17:25, Dave Martin wrote: >>> On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: > > [...] > >>>> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > > [...] > >>>> +static int fake_sigreturn_bad_magic_run(struct tdescr *td, >>>> + siginfo_t *si, ucontext_t *uc) >>>> +{ >>>> + size_t resv_sz, offset; >>>> + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; >>>> + >>>> + /* just to fill the ucontext_t with something real */ >>>> + if (!get_current_context(td, &sf.uc)) >>>> + return 1; >>>> + >>>> + resv_sz = GET_SF_RESV_SIZE(sf); >>>> + /* >>>> + * find the terminator, preserving existing headers >>>> + * and verify amount of spare room in __reserved area. >>>> + */ >>>> + head = get_terminator(shead, resv_sz, &offset); >>>> + /* >>>> + * try stripping extra_context header when low on space: >>>> + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC >>>> + * and the other for the usual terminator. >>>> + */ >>>> + if (head && resv_sz - offset < HDR_SZ * 2) { >>> >>> Can we factor out this logic for finding space in the signal frame? >>> >>> We do pretty much the same thing in all the fake_sigreturn tests... >> >> Ok >>> >>>> + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", >>>> + resv_sz - offset); >>>> + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); >>>> + } >>>> + /* just give up and timeout if still not enough space */ >>> >>> Do we actually time out? I don't see where we actually wait, so doesn't >>> test_run() just fail immediately? >>> >>> The same applies to all the other fake_sigreturn tests too. >>> >> Right. It is probably a leftover. >> >> SIGALRM is used as an extreme measure to kill tests gone bad, but this >> can happen only once the fake sigframe has been effectively placed on the stack >> and sigreturned. > > OK, so this gets reported as a test failure because with no SIGSEGV, > nothing ever sets td->pass? Yes exactly. End result is based on value on td->pass, in case of abrupt termination or timeout nobody sets td->pass ever. > > This is probably OK for now, though I wonder whether this should be > reported as a skipped test instead. > > In case of doubt, reporting a failure is preferable anyway, since that > will encourage people actually to investigate what went wrong. > As of now I never skip a test in fact...also tests for unsupported features are built and run expecting a SIGILL, and reported as PASS in that case. Cristian > [...] > > Cheers > ---Dave >
On Wed, Sep 04, 2019 at 11:37:36AM +0100, Cristian Marussi wrote: > On 04/09/2019 11:05, Dave Martin wrote: > > On Fri, Aug 30, 2019 at 03:29:29PM +0100, Cristian Marussi wrote: > >> Hi > >> > >> On 13/08/2019 17:25, Dave Martin wrote: > >>> On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: > > > > [...] > > > >>>> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > > > > [...] > > > >>>> +static int fake_sigreturn_bad_magic_run(struct tdescr *td, > >>>> + siginfo_t *si, ucontext_t *uc) > >>>> +{ > >>>> + size_t resv_sz, offset; > >>>> + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; > >>>> + > >>>> + /* just to fill the ucontext_t with something real */ > >>>> + if (!get_current_context(td, &sf.uc)) > >>>> + return 1; > >>>> + > >>>> + resv_sz = GET_SF_RESV_SIZE(sf); > >>>> + /* > >>>> + * find the terminator, preserving existing headers > >>>> + * and verify amount of spare room in __reserved area. > >>>> + */ > >>>> + head = get_terminator(shead, resv_sz, &offset); > >>>> + /* > >>>> + * try stripping extra_context header when low on space: > >>>> + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC > >>>> + * and the other for the usual terminator. > >>>> + */ > >>>> + if (head && resv_sz - offset < HDR_SZ * 2) { > >>> > >>> Can we factor out this logic for finding space in the signal frame? > >>> > >>> We do pretty much the same thing in all the fake_sigreturn tests... > >> > >> Ok > >>> > >>>> + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", > >>>> + resv_sz - offset); > >>>> + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); > >>>> + } > >>>> + /* just give up and timeout if still not enough space */ > >>> > >>> Do we actually time out? I don't see where we actually wait, so doesn't > >>> test_run() just fail immediately? > >>> > >>> The same applies to all the other fake_sigreturn tests too. > >>> > >> Right. It is probably a leftover. > >> > >> SIGALRM is used as an extreme measure to kill tests gone bad, but this > >> can happen only once the fake sigframe has been effectively placed on the stack > >> and sigreturned. > > > > OK, so this gets reported as a test failure because with no SIGSEGV, > > nothing ever sets td->pass? > > Yes exactly. End result is based on value on td->pass, in case of abrupt > termination or timeout nobody sets td->pass ever. > > > > This is probably OK for now, though I wonder whether this should be > > reported as a skipped test instead. > > > > In case of doubt, reporting a failure is preferable anyway, since that > > will encourage people actually to investigate what went wrong. > > > > As of now I never skip a test in fact...also tests for unsupported features > are built and run expecting a SIGILL, and reported as PASS in that case. OK, just wanted to check I'd understood correcly. Cheers ---Dave
diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile index 8c8d08be4b0d..b3dcf315b5a4 100644 --- a/tools/testing/selftests/arm64/signal/Makefile +++ b/tools/testing/selftests/arm64/signal/Makefile @@ -80,7 +80,7 @@ endif # Common test-unit targets to build common-layout test-cases executables # Needs secondary expansion to properly include the testcase c-file in pre-reqs .SECONDEXPANSION: -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h @if [ ! -d $(khdr_dir) ]; then \ echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S new file mode 100644 index 000000000000..6262b877400b --- /dev/null +++ b/tools/testing/selftests/arm64/signal/signals.S @@ -0,0 +1,64 @@ +/* + * SPDX-License-Identifier: GPL-2.0 + * Copyright (C) 2019 ARM Limited + */ + +#include <asm/unistd.h> + +.section ".rodata", "a" +call_fmt: + .asciz "Calling sigreturn with fake sigframe sized:%zd at calculated SP @%08lX\n" + +.text + +.globl fake_sigreturn + +/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:alignment_SP */ +fake_sigreturn: + mov x20, x0 + mov x21, x1 + mov x22, x2 + mov x23, sp + + /* create space on the stack for fake sigframe..."x22"-aligned */ + mov x0, #0 + add x0, x21, x22 + sub x22, x22, #1 + bic x0, x0, x22 + sub x23, x23, x0 + + ldr x0, =call_fmt + mov x1, x21 + mov x2, x23 + bl printf + + mov sp, x23 + + /* now fill it with the provided content... */ + mov x0, sp + mov x1, x20 + mov x2, x21 + bl memcpy + + /* + * Here saving a last minute SP to current->token acts as a marker: + * if we got here, we are successfully faking a sigreturn; in other + * words we are sure no bad fatal signal has been raised till now + * for unrelated reasons, so we should consider the possibl observed + * fatal signal like SEGV coming from Kernel restore_sigframe() and + * triggered as expected from our test-case. + * For simplicity this assumes that current field 'token' is laid out + * as first in struct tdescr + */ + ldr x0, current + str x23, [x0] + /* SP is already pointing back to the just built fake sigframe here */ + mov x8, #__NR_rt_sigreturn + svc #0 + + /* + * Above sigreturn should not return...looping here leads to a timeout + * and ensure proper and clean test failure, instead of jumping around + * on a potentially corrupted stack. + */ + b . diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h index ce35be8ebc8e..2a71da7e6695 100644 --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h @@ -12,4 +12,5 @@ int test_run(struct tdescr *td); void test_result(struct tdescr *td); bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); +int fake_sigreturn(void *sigframe, size_t sz, int alignment); #endif diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore index a48a118b1a1a..0ea6fdc3765c 100644 --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -4,3 +4,4 @@ mangle_pstate_invalid_mode_el1 mangle_pstate_invalid_mode_el2 mangle_pstate_invalid_mode_el3 mangle_pstate_ssbs_regs +fake_sigreturn_bad_magic diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c new file mode 100644 index 000000000000..b4c063e02a7a --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ + +#include <stdio.h> +#include <ucontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +struct fake_sigframe sf; + +static int fake_sigreturn_bad_magic_run(struct tdescr *td, + siginfo_t *si, ucontext_t *uc) +{ + size_t resv_sz, offset; + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; + + /* just to fill the ucontext_t with something real */ + if (!get_current_context(td, &sf.uc)) + return 1; + + resv_sz = GET_SF_RESV_SIZE(sf); + /* + * find the terminator, preserving existing headers + * and verify amount of spare room in __reserved area. + */ + head = get_terminator(shead, resv_sz, &offset); + /* + * try stripping extra_context header when low on space: + * we need at least 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC + * and the other for the usual terminator. + */ + if (head && resv_sz - offset < HDR_SZ * 2) { + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", + resv_sz - offset); + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset); + } + /* just give up and timeout if still not enough space */ + if (head && resv_sz - offset >= HDR_SZ) { + fprintf(stderr, "Mangling template header. Spare space:%zd\n", + resv_sz - offset); + /* + * use a well known NON existent bad magic...something + * we should pretty sure won't be ever defined in Kernel + */ + head->magic = KSFT_BAD_MAGIC; + head->size = HDR_SZ; + write_terminator_record(GET_RESV_NEXT_HEAD(head)); + + ASSERT_BAD_CONTEXT(&sf.uc); + fake_sigreturn(&sf, sizeof(sf), 16); + } + + return 1; +} + +struct tdescr tde = { + .name = "FAKE_SIGRETURN_BAD_MAGIC", + .descr = "Triggers a fake sigreturn with a sigframe including a bad non-existent magic", + .sig_ok = SIGSEGV, + .timeout = 3, + .run = fake_sigreturn_bad_magic_run, +};
Added a simple fake_sigreturn testcase which builds a ucontext_t with a bad magic header and place it onto the stack. Expects a SIGSEGV on test PASS. This commit also introduces a common utility assembly function to invoke a sigreturn using a fake provided sigframe. Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- tools/testing/selftests/arm64/signal/Makefile | 2 +- .../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++ .../arm64/signal/test_signals_utils.h | 1 + .../arm64/signal/testcases/.gitignore | 1 + .../testcases/fake_sigreturn_bad_magic.c | 63 ++++++++++++++++++ 5 files changed, 130 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/arm64/signal/signals.S create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c