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authorAnton Blanchard <anton@samba.org>2014-08-26 12:44:15 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-05 14:54:14 -0700
commit6956c1873a36168d2187980d51eb31ee86139336 (patch)
tree6eec8d7d683fe7029e0a6af8b2ddd3a0cf431f88
parent90d52e914efdb0f22779888f181f232ce453592e (diff)
downloadlinux-linaro-stable-6956c1873a36168d2187980d51eb31ee86139336.tar.gz
powerpc/perf: Fix ABIv2 kernel backtraces
commit 85101af13bb854a6572fa540df7c7201958624b9 upstream. ABIv2 kernels are failing to backtrace through the kernel. An example: 39.30% readseek2_proce [kernel.kallsyms] [k] find_get_entry | --- find_get_entry __GI___libc_read The problem is in valid_next_sp() where we check that the new stack pointer is at least STACK_FRAME_OVERHEAD below the previous one. ABIv1 has a minimum stack frame size of 112 bytes consisting of 48 bytes and 64 bytes of parameter save area. ABIv2 changes that to 32 bytes with no paramter save area. STACK_FRAME_OVERHEAD is in theory the minimum stack frame size, but we over 240 uses of it, some of which assume that it includes space for the parameter area. We need to work through all our stack defines and rationalise them but let's fix perf now by creating STACK_FRAME_MIN_SIZE and using in valid_next_sp(). This fixes the issue: 30.64% readseek2_proce [kernel.kallsyms] [k] find_get_entry | --- find_get_entry pagecache_get_page generic_file_read_iter new_sync_read vfs_read sys_read syscall_exit __GI___libc_read Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/powerpc/include/asm/ptrace.h7
-rw-r--r--arch/powerpc/perf/callchain.c2
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index becc08e6a65c..637c97fcbeb5 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -35,6 +35,12 @@
STACK_FRAME_OVERHEAD + 288)
#define STACK_FRAME_MARKER 12
+#if defined(_CALL_ELF) && _CALL_ELF == 2
+#define STACK_FRAME_MIN_SIZE 32
+#else
+#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD
+#endif
+
/* Size of dummy stack frame allocated when calling signal handler. */
#define __SIGNAL_FRAMESIZE 128
#define __SIGNAL_FRAMESIZE32 64
@@ -46,6 +52,7 @@
#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773)
#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
#define STACK_FRAME_MARKER 2
+#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD
/* Size of stack frame allocated when calling signal handler. */
#define __SIGNAL_FRAMESIZE 64
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index 74d1e780748b..2396dda282cd 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -35,7 +35,7 @@ static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
return 0; /* must be 16-byte aligned */
if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
return 0;
- if (sp >= prev_sp + STACK_FRAME_OVERHEAD)
+ if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
return 1;
/*
* sp could decrease when we jump off an interrupt stack