[REVIEW][PATCH 13/17] signal/powerpc: Replace FPE_FIXME with FPE_FLTUNK

[REVIEW][PATCH 13/17] signal/powerpc: Replace FPE_FIXME with FPE_FLTUNK

[Eric W. Biederman]

Using an si_code of 0 that aliases with SI_USER is clearly the
wrong thing todo, and causes problems in interesting ways.

The newly defined FPE_FLTUNK semantically appears to fit the
bill so use it instead.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Kumar Gala <kumar.gala@freescale.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc:  linuxppc-dev@lists.ozlabs.org
Fixes: 9bad068c24d7 ("[PATCH] ppc32: support for e500 and 85xx")
Fixes: 0ed70f6105ef ("PPC32: Provide proper siginfo information on various exceptions.")
History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/powerpc/include/uapi/asm/siginfo.h | 7 -------
 arch/powerpc/kernel/traps.c             | 6 +++---
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/uapi/asm/siginfo.h b/arch/powerpc/include/uapi/asm/siginfo.h
index 9f142451a01f..0437afc9ef3c 100644
--- a/arch/powerpc/include/uapi/asm/siginfo.h
+++ b/arch/powerpc/include/uapi/asm/siginfo.h
@@ -15,13 +15,6 @@
 
 #include <asm-generic/siginfo.h>
 
-/*
- * SIGFPE si_codes
- */
-#ifdef __KERNEL__
-#define FPE_FIXME	0	/* Broken dup of SI_USER */
-#endif /* __KERNEL__ */
-
 /*
  * SIGTRAP si_codes
  */
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 087855caf6a9..fdf9400beec8 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1031,7 +1031,7 @@ static void emulate_single_step(struct pt_regs *regs)
 
 static inline int __parse_fpscr(unsigned long fpscr)
 {
-	int ret = FPE_FIXME;
+	int ret = FPE_FLTUNK;
 
 	/* Invalid operation */
 	if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
@@ -1972,7 +1972,7 @@ void SPEFloatingPointException(struct pt_regs *regs)
 	extern int do_spe_mathemu(struct pt_regs *regs);
 	unsigned long spefscr;
 	int fpexc_mode;
-	int code = FPE_FIXME;
+	int code = FPE_FLTUNK;
 	int err;
 
 	flush_spe_to_thread(current);
@@ -2041,7 +2041,7 @@ void SPEFloatingPointRoundException(struct pt_regs *regs)
 		printk(KERN_ERR "unrecognized spe instruction "
 		       "in %s at %lx\n", current->comm, regs->nip);
 	} else {
-		_exception(SIGFPE, regs, FPE_FIXME, regs->nip);
+		_exception(SIGFPE, regs, FPE_FLTUNK, regs->nip);
 		return;
 	}
 }
-- 
2.14.1

[REVIEW][PATCH 15/17] signal: Add TRAP_UNK si_code for undiagnosted trap exceptions

[Eric W. Biederman]

Both powerpc and alpha have cases where they wronly set si_code to 0
in combination with SIGTRAP and don't mean SI_USER.

About half the time this is because the architecture can not report
accurately what kind of trap exception triggered the trap exception.
The other half the time it looks like no one has bothered to
figure out an appropriate si_code.

For the cases where the architecture does not have enough information
or is too lazy to figure out exactly what kind of trap exception
it is define TRAP_UNK.

Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/x86/kernel/signal_compat.c    | 2 +-
 include/uapi/asm-generic/siginfo.h | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 14c057f29979..9ccbf0576cd0 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/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 != 7);
 	BUILD_BUG_ON(NSIGBUS  != 5);
-	BUILD_BUG_ON(NSIGTRAP != 4);
+	BUILD_BUG_ON(NSIGTRAP != 5);
 	BUILD_BUG_ON(NSIGCHLD != 6);
 	BUILD_BUG_ON(NSIGSYS  != 1);
 
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 558b902f18d4..80e2a7227205 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -249,7 +249,8 @@ typedef struct siginfo {
 #define TRAP_TRACE	2	/* process trace trap */
 #define TRAP_BRANCH     3	/* process taken branch trap */
 #define TRAP_HWBKPT     4	/* hardware breakpoint/watchpoint */
-#define NSIGTRAP	4
+#define TRAP_UNK	5	/* undiagnosed trap */
+#define NSIGTRAP	5
 
 /*
  * There is an additional set of SIGTRAP si_codes used by ptrace
-- 
2.14.1

[REVIEW][PATCH 17/17] signal/powerpc: Replace TRAP_FIXME with TRAP_UNK

[Eric W. Biederman]

Using an si_code of 0 that aliases with SI_USER is clearly the wrong
thing todo, and causes problems in interesting ways.

For use in unknown_exception the recently defined TRAP_UNK
semantically is a perfect fit.  For use in RunModeException it looks
like something more specific than TRAP_UNK could be used.  No one has
bothered to find a better fit than the broken si_code of 0 in all of
these years and I don't see an obvious better fit so TRAP_UNK is
switching RunModeException to return TRAP_UNK is clearly an
improvement.

Recent history suggests no actually cares about crazy corner
cases of the kernel behavior like this so I don't expect any
regressions from changing this.  However if something does
happen this change is easy to revert.

Though I wonder if SIGKILL might not be a better fit.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Kumar Gala <kumar.gala@freescale.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Fixes: 9bad068c24d7 ("[PATCH] ppc32: support for e500 and 85xx")
Fixes: 0ed70f6105ef ("PPC32: Provide proper siginfo information on various exceptions.")
History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/powerpc/include/uapi/asm/siginfo.h | 8 --------
 arch/powerpc/kernel/traps.c             | 4 ++--
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/uapi/asm/siginfo.h b/arch/powerpc/include/uapi/asm/siginfo.h
index 0437afc9ef3c..1d51d9b88221 100644
--- a/arch/powerpc/include/uapi/asm/siginfo.h
+++ b/arch/powerpc/include/uapi/asm/siginfo.h
@@ -15,12 +15,4 @@
 
 #include <asm-generic/siginfo.h>
 
-/*
- * SIGTRAP si_codes
- */
-#ifdef __KERNEL__
-#define TRAP_FIXME	0	/* Broken dup of SI_USER */
-#endif /* __KERNEL__ */
-
-
 #endif	/* _ASM_POWERPC_SIGINFO_H */
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index fdf9400beec8..0e17dcb48720 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -969,7 +969,7 @@ void unknown_exception(struct pt_regs *regs)
 	printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
 	       regs->nip, regs->msr, regs->trap);
 
-	_exception(SIGTRAP, regs, TRAP_FIXME, 0);
+	_exception(SIGTRAP, regs, TRAP_UNK, 0);
 
 	exception_exit(prev_state);
 }
@@ -991,7 +991,7 @@ void instruction_breakpoint_exception(struct pt_regs *regs)
 
 void RunModeException(struct pt_regs *regs)
 {
-	_exception(SIGTRAP, regs, TRAP_FIXME, 0);
+	_exception(SIGTRAP, regs, TRAP_UNK, 0);
 }
 
 void single_step_exception(struct pt_regs *regs)
-- 
2.14.1