signal: Introduce TRAP_PERF si_code and si_perf to siginfo

Introduces the TRAP_PERF si_code, and associated siginfo_t field si_perf. These will be used by the perf event subsystem to send signals (if requested) to the task where an event occurred. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k Acked-by: Arnd Bergmann <arnd@arndb.de> # asm-generic Link: https://lkml.kernel.org/r/20210408103605.1676875-6-elver@google.com

Author: melver

arch/m68k/kernel/signal.c

@@ -622,6 +622,9 @@ static inline void siginfo_build_tests(void)
 /* _sigfault._addr_pkey */
 BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
 
+/* _sigfault._perf */
+BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
+
 /* _sigpoll */
 BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x0c);
 BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x10);

arch/x86/kernel/signal_compat.c

@@ -29,7 +29,7 @@ static inline void signal_compat_build_tests(void)
 BUILD_BUG_ON(NSIGFPE != 15);
 BUILD_BUG_ON(NSIGSEGV != 9);
 BUILD_BUG_ON(NSIGBUS != 5);
-BUILD_BUG_ON(NSIGTRAP != 5);
+BUILD_BUG_ON(NSIGTRAP != 6);
 BUILD_BUG_ON(NSIGCHLD != 6);
 BUILD_BUG_ON(NSIGSYS != 2);
 
@@ -138,6 +138,9 @@ static inline void signal_compat_build_tests(void)
 BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
 
+BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
+BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+
 CHECK_CSI_OFFSET(_sigpoll);
 CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int));
 CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));

fs/signalfd.c

@@ -134,6 +134,10 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 #endif
 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 break;
+case SIL_PERF_EVENT:
+new.ssi_addr = (long) kinfo->si_addr;
+new.ssi_perf = kinfo->si_perf;
+break;
 case SIL_CHLD:
 new.ssi_pid = kinfo->si_pid;
 new.ssi_uid = kinfo->si_uid;

include/linux/compat.h

@@ -236,6 +236,8 @@ typedef struct compat_siginfo {
 char _dummy_pkey[__COMPAT_ADDR_BND_PKEY_PAD];
 u32 _pkey;
 } _addr_pkey;
+/* used when si_code=TRAP_PERF */
+compat_u64 _perf;
 };
 } _sigfault;
 

include/linux/signal.h

@@ -43,6 +43,7 @@ enum siginfo_layout {
 SIL_FAULT_MCEERR,
 SIL_FAULT_BNDERR,
 SIL_FAULT_PKUERR,
+SIL_PERF_EVENT,
 SIL_CHLD,
 SIL_RT,
 SIL_SYS,

include/uapi/asm-generic/siginfo.h

@@ -91,6 +91,8 @@ union __sifields {
 char _dummy_pkey[__ADDR_BND_PKEY_PAD];
 __u32 _pkey;
 } _addr_pkey;
+/* used when si_code=TRAP_PERF */
+__u64 _perf;
 };
 } _sigfault;
 
@@ -155,6 +157,7 @@ typedef struct siginfo {
 #define si_lower_sifields._sigfault._addr_bnd._lower
 #define si_upper_sifields._sigfault._addr_bnd._upper
 #define si_pkey_sifields._sigfault._addr_pkey._pkey
+#define si_perf_sifields._sigfault._perf
 #define si_band_sifields._sigpoll._band
 #define si_fd_sifields._sigpoll._fd
 #define si_call_addr_sifields._sigsys._call_addr
@@ -253,7 +256,8 @@ typedef struct siginfo {
 #define TRAP_BRANCH 3/* process taken branch trap */
 #define TRAP_HWBKPT 4/* hardware breakpoint/watchpoint */
 #define TRAP_UNK5/* undiagnosed trap */
-#define NSIGTRAP5
+#define TRAP_PERF6/* perf event with sigtrap=1 */
+#define NSIGTRAP6
 
 /*
  * There is an additional set of SIGTRAP si_codes used by ptrace

include/uapi/linux/signalfd.h

@@ -39,6 +39,8 @@ struct signalfd_siginfo {
 __s32 ssi_syscall;
 __u64 ssi_call_addr;
 __u32 ssi_arch;
+__u32 __pad3;
+__u64 ssi_perf;
 
 /*
  * Pad strcture to 128 bytes. Remember to update the
@@ -49,7 +51,7 @@ struct signalfd_siginfo {
  * comes out of a read(2) and we really don't want to have
  * a compat on read(2).
  */
-__u8 __pad[28];
+__u8 __pad[16];
 };
 
 

kernel/signal.c

@@ -1199,6 +1199,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 case SIL_FAULT_MCEERR:
 case SIL_FAULT_BNDERR:
 case SIL_FAULT_PKUERR:
+case SIL_PERF_EVENT:
 case SIL_SYS:
 ret = false;
 break;
@@ -2531,6 +2532,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 case SIL_FAULT_MCEERR:
 case SIL_FAULT_BNDERR:
 case SIL_FAULT_PKUERR:
+case SIL_PERF_EVENT:
 ksig->info.si_addr = arch_untagged_si_addr(
 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 break;
@@ -3333,6 +3335,10 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 #endif
 to->si_pkey = from->si_pkey;
 break;
+case SIL_PERF_EVENT:
+to->si_addr = ptr_to_compat(from->si_addr);
+to->si_perf = from->si_perf;
+break;
 case SIL_CHLD:
 to->si_pid = from->si_pid;
 to->si_uid = from->si_uid;
@@ -3413,6 +3419,10 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 #endif
 to->si_pkey = from->si_pkey;
 break;
+case SIL_PERF_EVENT:
+to->si_addr = compat_ptr(from->si_addr);
+to->si_perf = from->si_perf;
+break;
 case SIL_CHLD:
 to->si_pid = from->si_pid;
 to->si_uid = from->si_uid;
@@ -4593,6 +4603,7 @@ static inline void siginfo_buildtime_checks(void)
 CHECK_OFFSET(si_lower);
 CHECK_OFFSET(si_upper);
 CHECK_OFFSET(si_pkey);
+CHECK_OFFSET(si_perf);
 
 /* sigpoll */
 CHECK_OFFSET(si_band);