From add0b32ef9146a8559a60aed54c37692a5f9d34f Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 30 Apr 2021 17:06:01 -0500 Subject: siginfo: Move si_trapno inside the union inside _si_fault It turns out that linux uses si_trapno very sparingly, and as such it can be considered extra information for a very narrow selection of signals, rather than information that is present with every fault reported in siginfo. As such move si_trapno inside the union inside of _si_fault. This results in no change in placement, and makes it eaiser to extend _si_fault in the future as this reduces the number of special cases. In particular with si_trapno included in the union it is no longer a concern that the union must be pointer aligned on most architectures because the union follows immediately after si_addr which is a pointer. This change results in a difference in siginfo field placement on sparc and alpha for the fields si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. These architectures do not implement the signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. Further these architecture have not yet implemented the userspace that would use si_perf. The point of this change is in fact to correct these placement issues before sparc or alpha grow userspace that cares. This change was discussed[1] and the agreement is that this change is currently safe. [1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com Acked-by: Marco Elver v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-5-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-1-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" --- kernel/signal.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index c3017aa8024a..65888aec65a0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void) /* sigfault */ CHECK_OFFSET(si_addr); + CHECK_OFFSET(si_trapno); CHECK_OFFSET(si_addr_lsb); CHECK_OFFSET(si_lower); CHECK_OFFSET(si_upper); -- cgit v1.2.3 From 9abcabe3111811aeae0f3a14e159b14248631875 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 30 Apr 2021 17:29:36 -0500 Subject: signal: Implement SIL_FAULT_TRAPNO Now that si_trapno is part of the union in _si_fault and available on all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to return SIL_FAULT_TRAPNO when the code assumes si_trapno is valid. There is room for future changes to reduce when si_trapno is valid but this is all that is needed to make si_trapno and the other members of the the union in _sigfault mutually exclusive. Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO and have the same code ignore si_trapno in in all other cases. v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-6-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-2-ebiederm@xmission.com Reviewed-by: Marco Elver Signed-off-by: "Eric W. Biederman" --- kernel/signal.c | 34 ++++++++++++---------------------- 1 file changed, 12 insertions(+), 22 deletions(-) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index 65888aec65a0..597594ee72de 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) case SIL_TIMER: case SIL_POLL: case SIL_FAULT: + case SIL_FAULT_TRAPNO: case SIL_FAULT_MCEERR: case SIL_FAULT_BNDERR: case SIL_FAULT_PKUERR: @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig) { switch (siginfo_layout(ksig->sig, ksig->info.si_code)) { case SIL_FAULT: + case SIL_FAULT_TRAPNO: case SIL_FAULT_MCEERR: case SIL_FAULT_BNDERR: case SIL_FAULT_PKUERR: @@ -3214,6 +3216,10 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code) #endif else if ((sig == SIGTRAP) && (si_code == TRAP_PERF)) layout = SIL_PERF_EVENT; +#ifdef __ARCH_SI_TRAPNO + else if (layout == SIL_FAULT) + layout = SIL_FAULT_TRAPNO; +#endif } else if (si_code <= NSIGPOLL) layout = SIL_POLL; @@ -3317,30 +3323,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, break; case SIL_FAULT: to->si_addr = ptr_to_compat(from->si_addr); -#ifdef __ARCH_SI_TRAPNO + break; + case SIL_FAULT_TRAPNO: + to->si_addr = ptr_to_compat(from->si_addr); to->si_trapno = from->si_trapno; -#endif break; case SIL_FAULT_MCEERR: to->si_addr = ptr_to_compat(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_addr_lsb = from->si_addr_lsb; break; case SIL_FAULT_BNDERR: to->si_addr = ptr_to_compat(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_lower = ptr_to_compat(from->si_lower); to->si_upper = ptr_to_compat(from->si_upper); break; case SIL_FAULT_PKUERR: to->si_addr = ptr_to_compat(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_pkey = from->si_pkey; break; case SIL_PERF_EVENT: @@ -3401,30 +3399,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, break; case SIL_FAULT: to->si_addr = compat_ptr(from->si_addr); -#ifdef __ARCH_SI_TRAPNO + break; + case SIL_FAULT_TRAPNO: + to->si_addr = compat_ptr(from->si_addr); to->si_trapno = from->si_trapno; -#endif break; case SIL_FAULT_MCEERR: to->si_addr = compat_ptr(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_addr_lsb = from->si_addr_lsb; break; case SIL_FAULT_BNDERR: to->si_addr = compat_ptr(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_lower = compat_ptr(from->si_lower); to->si_upper = compat_ptr(from->si_upper); break; case SIL_FAULT_PKUERR: to->si_addr = compat_ptr(from->si_addr); -#ifdef __ARCH_SI_TRAPNO - to->si_trapno = from->si_trapno; -#endif to->si_pkey = from->si_pkey; break; case SIL_PERF_EVENT: -- cgit v1.2.3 From af5eeab7e8e8c2f0fad10e4ab8cc8092012a2d5b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 2 May 2021 14:27:24 -0500 Subject: signal: Factor force_sig_perf out of perf_sigtrap Separate filling in siginfo for TRAP_PERF from deciding that siginal needs to be sent. There are enough little details that need to be correct when properly filling in siginfo_t that it is easy to make mistakes if filling in the siginfo_t is in the same function with other logic. So factor out force_sig_perf to reduce the cognative load of on reviewers, maintainers and implementors. v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-10-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-3-ebiederm@xmission.com Reviewed-by: Marco Elver Acked-by: Peter Zijlstra (Intel) Signed-off-by: "Eric W. Biederman" --- kernel/events/core.c | 11 ++--------- kernel/signal.c | 13 +++++++++++++ 2 files changed, 15 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 928b166d888e..48ea8863183b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event) static void perf_sigtrap(struct perf_event *event) { - struct kernel_siginfo info; - /* * We'd expect this to only occur if the irq_work is delayed and either * ctx->task or current has changed in the meantime. This can be the @@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event) if (current->flags & PF_EXITING) return; - clear_siginfo(&info); - info.si_signo = SIGTRAP; - info.si_code = TRAP_PERF; - info.si_errno = event->attr.type; - info.si_perf = event->attr.sig_data; - info.si_addr = (void __user *)event->pending_addr; - force_sig_info(&info); + force_sig_perf((void __user *)event->pending_addr, + event->attr.type, event->attr.sig_data); } static void perf_pending_event_disable(struct perf_event *event) diff --git a/kernel/signal.c b/kernel/signal.c index 597594ee72de..3a18d13c39b2 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1763,6 +1763,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey) } #endif +int force_sig_perf(void __user *addr, u32 type, u64 sig_data) +{ + struct kernel_siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGTRAP; + info.si_errno = type; + info.si_code = TRAP_PERF; + info.si_addr = addr; + info.si_perf = sig_data; + return force_sig_info(&info); +} + /* For the crazy architectures that include trap information in * the errno field, instead of an actual errno value. */ -- cgit v1.2.3 From 0683b53197b55343a166f1507086823030809a19 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 2 May 2021 17:28:31 -0500 Subject: signal: Deliver all of the siginfo perf data in _perf Don't abuse si_errno and deliver all of the perf data in _perf member of siginfo_t. Note: The data field in the perf data structures in a u64 to allow a pointer to be encoded without needed to implement a 32bit and 64bit version of the same structure. There already exists a 32bit and 64bit versions siginfo_t, and the 32bit version can not include a 64bit member as it only has 32bit alignment. So unsigned long is used in siginfo_t instead of a u64 as unsigned long can encode a pointer on all architectures linux supports. v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com v3: https://lkml.kernel.org/r/20210505141101.11519-11-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-4-ebiederm@xmission.com Reviewed-by: Marco Elver Signed-off-by: "Eric W. Biederman" --- kernel/signal.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index 3a18d13c39b2..dca53515ae3f 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1768,11 +1768,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data) struct kernel_siginfo info; clear_siginfo(&info); - info.si_signo = SIGTRAP; - info.si_errno = type; - info.si_code = TRAP_PERF; - info.si_addr = addr; - info.si_perf = sig_data; + info.si_signo = SIGTRAP; + info.si_errno = 0; + info.si_code = TRAP_PERF; + info.si_addr = addr; + info.si_perf_data = sig_data; + info.si_perf_type = type; + return force_sig_info(&info); } @@ -3356,7 +3358,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, break; case SIL_PERF_EVENT: to->si_addr = ptr_to_compat(from->si_addr); - to->si_perf = from->si_perf; + to->si_perf_data = from->si_perf_data; + to->si_perf_type = from->si_perf_type; break; case SIL_CHLD: to->si_pid = from->si_pid; @@ -3432,7 +3435,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, break; case SIL_PERF_EVENT: to->si_addr = compat_ptr(from->si_addr); - to->si_perf = from->si_perf; + to->si_perf_data = from->si_perf_data; + to->si_perf_type = from->si_perf_type; break; case SIL_CHLD: to->si_pid = from->si_pid; @@ -4615,7 +4619,8 @@ static inline void siginfo_buildtime_checks(void) CHECK_OFFSET(si_lower); CHECK_OFFSET(si_upper); CHECK_OFFSET(si_pkey); - CHECK_OFFSET(si_perf); + CHECK_OFFSET(si_perf_data); + CHECK_OFFSET(si_perf_type); /* sigpoll */ CHECK_OFFSET(si_band); -- cgit v1.2.3