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From: Michal Suchanek <msuchanek@suse.de>
To: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v12 4/8] powerpc/perf: consolidate valid_user_sp ->
 invalid_user_sp
Date: Fri, 20 Mar 2020 11:20:15 +0100
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Cc: Mark Rutland <mark.rutland@arm.com>,
 Gustavo Luiz Duarte <gustavold@linux.ibm.com>,
 Peter Zijlstra <peterz@infradead.org>,
 Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
 linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
 Jiri Olsa <jolsa@redhat.com>, Rob Herring <robh@kernel.org>,
 Michael Neuling <mikey@neuling.org>,
 Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
 Masahiro Yamada <masahiroy@kernel.org>, Nayna Jain <nayna@linux.ibm.com>,
 Alexander Shishkin <alexander.shishkin@linux.intel.com>,
 Ingo Molnar <mingo@redhat.com>, Allison Randal <allison@lohutok.net>,
 Jordan Niethe <jniethe5@gmail.com>, Michal Suchanek <msuchanek@suse.de>,
 Valentin Schneider <valentin.schneider@arm.com>, Arnd Bergmann <arnd@arndb.de>,
 Arnaldo Carvalho de Melo <acme@kernel.org>,
 Alexander Viro <viro@zeniv.linux.org.uk>,
 Jonathan Cameron <Jonathan.Cameron@huawei.com>,
 Namhyung Kim <namhyung@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
 Hari Bathini <hbathini@linux.ibm.com>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Nicholas Piggin <npiggin@gmail.com>, Claudio Carvalho <cclaudio@linux.ibm.com>,
 Eric Richter <erichte@linux.ibm.com>,
 "Eric W. Biederman" <ebiederm@xmission.com>, linux-fsdevel@vger.kernel.org,
 "David S. Miller" <davem@davemloft.net>,
 Thiago Jung Bauermann <bauerman@linux.ibm.com>
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

Merge the 32bit and 64bit version.

Halve the check constants on 32bit.

Use STACK_TOP since it is defined.

Passing is_64 is now redundant since is_32bit_task() is used to
determine which callchain variant should be used. Use STACK_TOP and
is_32bit_task() directly.

This removes a page from the valid 32bit area on 64bit:
 #define TASK_SIZE_USER32 (0x0000000100000000UL - (1 * PAGE_SIZE))
 #define STACK_TOP_USER32 TASK_SIZE_USER32

Change return value to bool. It is inverted by users anyway.

Change to invalid_user_sp to avoid inverting the return value twice.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
v8: new patch
v11: simplify by using is_32bit_task()
v12:
 - simplify by precalculating subexpresions
 - change return value to bool
 - remove double inversion
---
 arch/powerpc/perf/callchain.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index c9a78c6e4361..001d0473a61f 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -102,6 +102,14 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 	}
 }
 
+static inline bool invalid_user_sp(unsigned long sp)
+{
+	unsigned long mask = is_32bit_task() ? 3 : 7;
+	unsigned long top = STACK_TOP - (is_32bit_task() ? 16 : 32);
+
+	return (!sp || (sp & mask) || (sp > top));
+}
+
 #ifdef CONFIG_PPC64
 /*
  * On 64-bit we don't want to invoke hash_page on user addresses from
@@ -161,13 +169,6 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
 	return read_user_stack_slow(ptr, ret, 8);
 }
 
-static inline int valid_user_sp(unsigned long sp, int is_64)
-{
-	if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
-		return 0;
-	return 1;
-}
-
 /*
  * 64-bit user processes use the same stack frame for RT and non-RT signals.
  */
@@ -226,7 +227,7 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
 
 	while (entry->nr < entry->max_stack) {
 		fp = (unsigned long __user *) sp;
-		if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
+		if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp))
 			return;
 		if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
 			return;
@@ -275,13 +276,6 @@ static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry
 {
 }
 
-static inline int valid_user_sp(unsigned long sp, int is_64)
-{
-	if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
-		return 0;
-	return 1;
-}
-
 #define __SIGNAL_FRAMESIZE32	__SIGNAL_FRAMESIZE
 #define sigcontext32		sigcontext
 #define mcontext32		mcontext
@@ -423,7 +417,7 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
 
 	while (entry->nr < entry->max_stack) {
 		fp = (unsigned int __user *) (unsigned long) sp;
-		if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
+		if (invalid_user_sp(sp) || read_user_stack_32(fp, &next_sp))
 			return;
 		if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
 			return;
-- 
2.23.0