[PATCH 0/3] ARC unwinder switch to .eh_frame

[PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

Hi Daniel,

Give these a shot and let me know if they work fine for you.
I'm working on some more improvements to unwinder which will follow
a bit later.

Thx,
-Vineet

Vineet Gupta (3):
  ARC: module: support R_ARC_32_PCREL relocation
  ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
  ARC: dw2 unwind: switch to .eh_frame based unwinding

 arch/arc/Makefile             |  2 ++
 arch/arc/include/asm/elf.h    |  3 +--
 arch/arc/kernel/entry.S       | 12 ------------
 arch/arc/kernel/module.c      | 19 ++++++++-----------
 arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
 arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
 6 files changed, 33 insertions(+), 42 deletions(-)

-- 
2.7.4

[PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

Hi Daniel,

Give these a shot and let me know if they work fine for you.
I'm working on some more improvements to unwinder which will follow
a bit later.

Thx,
-Vineet

Vineet Gupta (3):
  ARC: module: support R_ARC_32_PCREL relocation
  ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
  ARC: dw2 unwind: switch to .eh_frame based unwinding

 arch/arc/Makefile             |  2 ++
 arch/arc/include/asm/elf.h    |  3 +--
 arch/arc/kernel/entry.S       | 12 ------------
 arch/arc/kernel/module.c      | 19 ++++++++-----------
 arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
 arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
 6 files changed, 33 insertions(+), 42 deletions(-)

-- 
2.7.4

[PATCH 1/3] ARC: module: support R_ARC_32_PCREL relocation

[Vineet Gupta]

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/elf.h | 3 +--
 arch/arc/kernel/module.c   | 6 ++++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arc/include/asm/elf.h b/arch/arc/include/asm/elf.h
index 51a99e25fe33..7096f97a1434 100644
--- a/arch/arc/include/asm/elf.h
+++ b/arch/arc/include/asm/elf.h
@@ -23,8 +23,7 @@
 /* ARC Relocations (kernel Modules only) */
 #define  R_ARC_32		0x4
 #define  R_ARC_32_ME		0x1B
-#define  R_ARC_S25H_PCREL	0x10
-#define  R_ARC_S25W_PCREL	0x11
+#define  R_ARC_32_PCREL		0x31
 
 /*to set parameters in the core dumps */
 #define ELF_ARCH		EM_ARCOMPACT
diff --git a/arch/arc/kernel/module.c b/arch/arc/kernel/module.c
index 376e04622962..576a238434a1 100644
--- a/arch/arc/kernel/module.c
+++ b/arch/arc/kernel/module.c
@@ -106,10 +106,12 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
 		 */
 		relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
 
-		if (likely(R_ARC_32_ME == relo_type))
+		if (likely(R_ARC_32_ME == relo_type))	/* ME ( S + A ) */
 			arc_write_me((unsigned short *)location, relocation);
-		else if (R_ARC_32 == relo_type)
+		else if (R_ARC_32 == relo_type)		/* ( S + A ) */
 			*((Elf32_Addr *) location) = relocation;
+		else if (R_ARC_32_PCREL == relo_type)	/* ( S + A ) - PDATA ) */
+			*((Elf32_Addr *) location) = relocation - location;
 		else
 			goto relo_err;
 
-- 
2.7.4

[PATCH 1/3] ARC: module: support R_ARC_32_PCREL relocation

[Vineet Gupta]

Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
---
 arch/arc/include/asm/elf.h | 3 +--
 arch/arc/kernel/module.c   | 6 ++++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arc/include/asm/elf.h b/arch/arc/include/asm/elf.h
index 51a99e25fe33..7096f97a1434 100644
--- a/arch/arc/include/asm/elf.h
+++ b/arch/arc/include/asm/elf.h
@@ -23,8 +23,7 @@
 /* ARC Relocations (kernel Modules only) */
 #define  R_ARC_32		0x4
 #define  R_ARC_32_ME		0x1B
-#define  R_ARC_S25H_PCREL	0x10
-#define  R_ARC_S25W_PCREL	0x11
+#define  R_ARC_32_PCREL		0x31
 
 /*to set parameters in the core dumps */
 #define ELF_ARCH		EM_ARCOMPACT
diff --git a/arch/arc/kernel/module.c b/arch/arc/kernel/module.c
index 376e04622962..576a238434a1 100644
--- a/arch/arc/kernel/module.c
+++ b/arch/arc/kernel/module.c
@@ -106,10 +106,12 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
 		 */
 		relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
 
-		if (likely(R_ARC_32_ME == relo_type))
+		if (likely(R_ARC_32_ME == relo_type))	/* ME ( S + A ) */
 			arc_write_me((unsigned short *)location, relocation);
-		else if (R_ARC_32 == relo_type)
+		else if (R_ARC_32 == relo_type)		/* ( S + A ) */
 			*((Elf32_Addr *) location) = relocation;
+		else if (R_ARC_32_PCREL == relo_type)	/* ( S + A ) - PDATA ) */
+			*((Elf32_Addr *) location) = relocation - location;
 		else
 			goto relo_err;
 
-- 
2.7.4

[PATCH 2/3] ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame

[Vineet Gupta]

This paves way for switching to .eh_frame based unwindiing

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/kernel/unwind.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 0587bf121d11..4e5dbe7617a1 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -111,6 +111,8 @@ UNW_REGISTER_INFO};
 #define DW_EH_PE_indirect 0x80
 #define DW_EH_PE_omit     0xff
 
+#define CIE_ID	0xffffffffUL
+
 typedef unsigned long uleb128_t;
 typedef signed long sleb128_t;
 
@@ -232,6 +234,7 @@ void __init arc_unwind_init(void)
 
 static const u32 bad_cie, not_fde;
 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
+static const u32 *__cie_for_fde(const u32 *fde);
 static signed fde_pointer_type(const u32 *cie);
 
 struct eh_frame_hdr_table_entry {
@@ -338,10 +341,9 @@ static void init_unwind_hdr(struct unwind_table *table,
 	for (fde = table->address, tableSize = table->size, n = 0;
 	     tableSize;
 	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
-		/* const u32 *cie = fde + 1 - fde[1] / sizeof(*fde); */
-		const u32 *cie = (const u32 *)(fde[1]);
+		const u32 *cie = __cie_for_fde(fde);
 
-		if (fde[1] == 0xffffffff)
+		if (fde[1] == CIE_ID)
 			continue;	/* this is a CIE */
 		ptr = (const u8 *)(fde + 2);
 		header->table[n].start = read_pointer(&ptr,
@@ -504,6 +506,16 @@ static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
 	return value;
 }
 
+static const u32 *__cie_for_fde(const u32 *fde)
+{
+	const u32 *cie;
+
+	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
+	cie = (u32 *) fde[1];
+
+	return cie;
+}
+
 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 {
 	const u32 *cie;
@@ -511,19 +523,18 @@ static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 	if (!*fde || (*fde & (sizeof(*fde) - 1)))
 		return &bad_cie;
 
-	if (fde[1] == 0xffffffff)
+	if (fde[1] == CIE_ID)
 		return &not_fde;	/* this is a CIE */
 
 	if ((fde[1] & (sizeof(*fde) - 1)))
 /* || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address) */
 		return NULL;	/* this is not a valid FDE */
 
-	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
-	cie = (u32 *) fde[1];
+	cie = __cie_for_fde(fde);
 
 	if (*cie <= sizeof(*cie) + 4 || *cie >= fde[1] - sizeof(*fde)
 	    || (*cie & (sizeof(*cie) - 1))
-	    || (cie[1] != 0xffffffff))
+	    || (cie[1] != CIE_ID))
 		return NULL;	/* this is not a (valid) CIE */
 	return cie;
 }
-- 
2.7.4

[PATCH 2/3] ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame

[Vineet Gupta]

This paves way for switching to .eh_frame based unwindiing

Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
---
 arch/arc/kernel/unwind.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 0587bf121d11..4e5dbe7617a1 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -111,6 +111,8 @@ UNW_REGISTER_INFO};
 #define DW_EH_PE_indirect 0x80
 #define DW_EH_PE_omit     0xff
 
+#define CIE_ID	0xffffffffUL
+
 typedef unsigned long uleb128_t;
 typedef signed long sleb128_t;
 
@@ -232,6 +234,7 @@ void __init arc_unwind_init(void)
 
 static const u32 bad_cie, not_fde;
 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
+static const u32 *__cie_for_fde(const u32 *fde);
 static signed fde_pointer_type(const u32 *cie);
 
 struct eh_frame_hdr_table_entry {
@@ -338,10 +341,9 @@ static void init_unwind_hdr(struct unwind_table *table,
 	for (fde = table->address, tableSize = table->size, n = 0;
 	     tableSize;
 	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
-		/* const u32 *cie = fde + 1 - fde[1] / sizeof(*fde); */
-		const u32 *cie = (const u32 *)(fde[1]);
+		const u32 *cie = __cie_for_fde(fde);
 
-		if (fde[1] == 0xffffffff)
+		if (fde[1] == CIE_ID)
 			continue;	/* this is a CIE */
 		ptr = (const u8 *)(fde + 2);
 		header->table[n].start = read_pointer(&ptr,
@@ -504,6 +506,16 @@ static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
 	return value;
 }
 
+static const u32 *__cie_for_fde(const u32 *fde)
+{
+	const u32 *cie;
+
+	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
+	cie = (u32 *) fde[1];
+
+	return cie;
+}
+
 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 {
 	const u32 *cie;
@@ -511,19 +523,18 @@ static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 	if (!*fde || (*fde & (sizeof(*fde) - 1)))
 		return &bad_cie;
 
-	if (fde[1] == 0xffffffff)
+	if (fde[1] == CIE_ID)
 		return &not_fde;	/* this is a CIE */
 
 	if ((fde[1] & (sizeof(*fde) - 1)))
 /* || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address) */
 		return NULL;	/* this is not a valid FDE */
 
-	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
-	cie = (u32 *) fde[1];
+	cie = __cie_for_fde(fde);
 
 	if (*cie <= sizeof(*cie) + 4 || *cie >= fde[1] - sizeof(*fde)
 	    || (*cie & (sizeof(*cie) - 1))
-	    || (cie[1] != 0xffffffff))
+	    || (cie[1] != CIE_ID))
 		return NULL;	/* this is not a (valid) CIE */
 	return cie;
 }
-- 
2.7.4

[PATCH 3/3] ARC: dw2 unwind: switch to .eh_frame based unwinding

[Vineet Gupta]

So finally after almost 8 years of dealing with .debug_frame, we are
finally switching to .eh_frame. The reason being stripped kernel
binaries had non-functional unwinder as .debug_frame was gone.
Also, in general .eh_frame seems more common way of doing unwinding.

This also folds a revert of f52e126cc747 ("ARC: unwind: ensure that
.debug_frame is generated (vs. .eh_frame)") to ensure that we start
getting .eh_frame

Reported-by: Daniel Mentz <danielmentz@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/Makefile             |  2 ++
 arch/arc/kernel/entry.S       | 12 ------------
 arch/arc/kernel/module.c      | 13 ++++---------
 arch/arc/kernel/unwind.c      |  5 ++---
 arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
 5 files changed, 13 insertions(+), 34 deletions(-)

diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index 601ed173080b..fc6ff8f09f23 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -66,6 +66,8 @@ endif
 
 endif
 
+cflags-$(CONFIG_ARC_DW2_UNWIND)		+= -fasynchronous-unwind-tables
+
 # By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok
 ifeq ($(atleast_gcc48),y)
 cflags-$(CONFIG_ARC_DW2_UNWIND)		+= -gdwarf-2
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 2efb0625331d..741712d4d6ff 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -61,18 +61,6 @@ ENTRY(ret_from_fork)
 	b    ret_from_exception
 END(ret_from_fork)
 
-#ifdef CONFIG_ARC_DW2_UNWIND
-; Workaround for bug 94179 (STAR ):
-; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
-; section (.debug_frame) as loadable. So we force it here.
-; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
-; would not work after a clean build due to kernel build system dependencies.
-.section .debug_frame, "wa",@progbits
-
-; Reset to .text as this file is included in entry-<isa>.S
-.section .text, "ax",@progbits
-#endif
-
 ;################### Non TLB Exception Handling #############################
 
 ; ---------------------------------------------
diff --git a/arch/arc/kernel/module.c b/arch/arc/kernel/module.c
index 576a238434a1..9a2849756022 100644
--- a/arch/arc/kernel/module.c
+++ b/arch/arc/kernel/module.c
@@ -22,13 +22,9 @@ static inline void arc_write_me(unsigned short *addr, unsigned long value)
 	*(addr + 1) = (value & 0xffff);
 }
 
-/* ARC specific section quirks - before relocation loop in generic loader
- *
- * For dwarf unwinding out of modules, this needs to
- * 1. Ensure the .debug_frame is allocatable (ARC Linker bug: despite
- *    -fasynchronous-unwind-tables it doesn't).
- * 2. Since we are iterating thru sec hdr tbl anyways, make a note of
- *    the exact section index, for later use.
+/*
+ * This gets called before relocation loop in generic loader
+ * Make a note of the section index of unwinding section
  */
 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 			      char *secstr, struct module *mod)
@@ -40,8 +36,7 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 	mod->arch.unw_info = NULL;
 
 	for (i = 1; i < hdr->e_shnum; i++) {
-		if (strcmp(secstr+sechdrs[i].sh_name, ".debug_frame") == 0) {
-			sechdrs[i].sh_flags |= SHF_ALLOC;
+		if (strcmp(secstr+sechdrs[i].sh_name, ".eh_frame") == 0) {
 			mod->arch.unw_sec_idx = i;
 			break;
 		}
diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 4e5dbe7617a1..61fd1ce63c56 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -111,7 +111,7 @@ UNW_REGISTER_INFO};
 #define DW_EH_PE_indirect 0x80
 #define DW_EH_PE_omit     0xff
 
-#define CIE_ID	0xffffffffUL
+#define CIE_ID	0
 
 typedef unsigned long uleb128_t;
 typedef signed long sleb128_t;
@@ -510,8 +510,7 @@ static const u32 *__cie_for_fde(const u32 *fde)
 {
 	const u32 *cie;
 
-	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
-	cie = (u32 *) fde[1];
+	cie = fde + 1 - fde[1] / sizeof(*fde);
 
 	return cie;
 }
diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 894e696bddaa..bb6d8c5ff2e9 100644
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -84,7 +84,7 @@ SECTIONS
 
 	/*
 	 * .exit.text is discard at runtime, not link time, to deal with
-	 * references from .debug_frame
+	 * references from unwinding sections
 	 * It will be init freed, being inside [__init_start : __init_end]
 	 */
 	.exit.text : { EXIT_TEXT }
@@ -120,18 +120,13 @@ SECTIONS
 
 #ifdef CONFIG_ARC_DW2_UNWIND
 	. = ALIGN(PAGE_SIZE);
-	.debug_frame  : {
+	.eh_frame  : {
 		__start_unwind = .;
-		*(.debug_frame)
+		*(.eh_frame)
 		__end_unwind = .;
 	}
-	/*
-	 * gcc 4.8 generates this for -fasynchonous-unwind-tables,
-	 * while we still use the .debug_frame based unwinder
-	 */
-	/DISCARD/ : {	*(.eh_frame) }
 #else
-	/DISCARD/ : {	*(.debug_frame) }
+	/DISCARD/ : {	*(.eh_frame) }
 #endif
 
 	NOTES
@@ -148,7 +143,7 @@ SECTIONS
 	}
 
 #ifndef CONFIG_DEBUG_INFO
-	/* open-coded because we need .debug_frame seperately for unwinding */
+	/DISCARD/ : { *(.debug_frame) }
 	/DISCARD/ : { *(.debug_aranges) }
 	/DISCARD/ : { *(.debug_pubnames) }
 	/DISCARD/ : { *(.debug_info) }
-- 
2.7.4

[PATCH 3/3] ARC: dw2 unwind: switch to .eh_frame based unwinding

[Vineet Gupta]

So finally after almost 8 years of dealing with .debug_frame, we are
finally switching to .eh_frame. The reason being stripped kernel
binaries had non-functional unwinder as .debug_frame was gone.
Also, in general .eh_frame seems more common way of doing unwinding.

This also folds a revert of f52e126cc747 ("ARC: unwind: ensure that
.debug_frame is generated (vs. .eh_frame)") to ensure that we start
getting .eh_frame

Reported-by: Daniel Mentz <danielmentz at google.com>
Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
---
 arch/arc/Makefile             |  2 ++
 arch/arc/kernel/entry.S       | 12 ------------
 arch/arc/kernel/module.c      | 13 ++++---------
 arch/arc/kernel/unwind.c      |  5 ++---
 arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
 5 files changed, 13 insertions(+), 34 deletions(-)

diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index 601ed173080b..fc6ff8f09f23 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -66,6 +66,8 @@ endif
 
 endif
 
+cflags-$(CONFIG_ARC_DW2_UNWIND)		+= -fasynchronous-unwind-tables
+
 # By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok
 ifeq ($(atleast_gcc48),y)
 cflags-$(CONFIG_ARC_DW2_UNWIND)		+= -gdwarf-2
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 2efb0625331d..741712d4d6ff 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -61,18 +61,6 @@ ENTRY(ret_from_fork)
 	b    ret_from_exception
 END(ret_from_fork)
 
-#ifdef CONFIG_ARC_DW2_UNWIND
-; Workaround for bug 94179 (STAR ):
-; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
-; section (.debug_frame) as loadable. So we force it here.
-; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
-; would not work after a clean build due to kernel build system dependencies.
-.section .debug_frame, "wa", at progbits
-
-; Reset to .text as this file is included in entry-<isa>.S
-.section .text, "ax", at progbits
-#endif
-
 ;################### Non TLB Exception Handling #############################
 
 ; ---------------------------------------------
diff --git a/arch/arc/kernel/module.c b/arch/arc/kernel/module.c
index 576a238434a1..9a2849756022 100644
--- a/arch/arc/kernel/module.c
+++ b/arch/arc/kernel/module.c
@@ -22,13 +22,9 @@ static inline void arc_write_me(unsigned short *addr, unsigned long value)
 	*(addr + 1) = (value & 0xffff);
 }
 
-/* ARC specific section quirks - before relocation loop in generic loader
- *
- * For dwarf unwinding out of modules, this needs to
- * 1. Ensure the .debug_frame is allocatable (ARC Linker bug: despite
- *    -fasynchronous-unwind-tables it doesn't).
- * 2. Since we are iterating thru sec hdr tbl anyways, make a note of
- *    the exact section index, for later use.
+/*
+ * This gets called before relocation loop in generic loader
+ * Make a note of the section index of unwinding section
  */
 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 			      char *secstr, struct module *mod)
@@ -40,8 +36,7 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 	mod->arch.unw_info = NULL;
 
 	for (i = 1; i < hdr->e_shnum; i++) {
-		if (strcmp(secstr+sechdrs[i].sh_name, ".debug_frame") == 0) {
-			sechdrs[i].sh_flags |= SHF_ALLOC;
+		if (strcmp(secstr+sechdrs[i].sh_name, ".eh_frame") == 0) {
 			mod->arch.unw_sec_idx = i;
 			break;
 		}
diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 4e5dbe7617a1..61fd1ce63c56 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -111,7 +111,7 @@ UNW_REGISTER_INFO};
 #define DW_EH_PE_indirect 0x80
 #define DW_EH_PE_omit     0xff
 
-#define CIE_ID	0xffffffffUL
+#define CIE_ID	0
 
 typedef unsigned long uleb128_t;
 typedef signed long sleb128_t;
@@ -510,8 +510,7 @@ static const u32 *__cie_for_fde(const u32 *fde)
 {
 	const u32 *cie;
 
-	/* cie = fde + 1 - fde[1] / sizeof(*fde); */
-	cie = (u32 *) fde[1];
+	cie = fde + 1 - fde[1] / sizeof(*fde);
 
 	return cie;
 }
diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 894e696bddaa..bb6d8c5ff2e9 100644
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -84,7 +84,7 @@ SECTIONS
 
 	/*
 	 * .exit.text is discard at runtime, not link time, to deal with
-	 * references from .debug_frame
+	 * references from unwinding sections
 	 * It will be init freed, being inside [__init_start : __init_end]
 	 */
 	.exit.text : { EXIT_TEXT }
@@ -120,18 +120,13 @@ SECTIONS
 
 #ifdef CONFIG_ARC_DW2_UNWIND
 	. = ALIGN(PAGE_SIZE);
-	.debug_frame  : {
+	.eh_frame  : {
 		__start_unwind = .;
-		*(.debug_frame)
+		*(.eh_frame)
 		__end_unwind = .;
 	}
-	/*
-	 * gcc 4.8 generates this for -fasynchonous-unwind-tables,
-	 * while we still use the .debug_frame based unwinder
-	 */
-	/DISCARD/ : {	*(.eh_frame) }
 #else
-	/DISCARD/ : {	*(.debug_frame) }
+	/DISCARD/ : {	*(.eh_frame) }
 #endif
 
 	NOTES
@@ -148,7 +143,7 @@ SECTIONS
 	}
 
 #ifndef CONFIG_DEBUG_INFO
-	/* open-coded because we need .debug_frame seperately for unwinding */
+	/DISCARD/ : { *(.debug_frame) }
 	/DISCARD/ : { *(.debug_aranges) }
 	/DISCARD/ : { *(.debug_pubnames) }
 	/DISCARD/ : { *(.debug_info) }
-- 
2.7.4

Re: [PATCH 0/3] ARC unwinder switch to .eh_frame

[Daniel Mentz]

Hi Vineet,

Thank you for your patches. I applied them, and verified that
unwinding works with code that is compiled into the kernel image as
well as kernel modules.
I confirmed that the .eh_frame section is present and that the
.debug_frame section is absent. I also verified that the file size of
the .ko files are small enough for our embedded platform and that
unnecessary sections like .debug_info, .debug_line, .debug_str etc.
are also absent.
Is there anything else you want me to test?
Thanks
Daniel


On Mon, Sep 19, 2016 at 2:49 PM, Vineet Gupta
<Vineet.Gupta1@synopsys.com> wrote:
> Hi Daniel,
>
> Give these a shot and let me know if they work fine for you.
> I'm working on some more improvements to unwinder which will follow
> a bit later.
>
> Thx,
> -Vineet
>
> Vineet Gupta (3):
>   ARC: module: support R_ARC_32_PCREL relocation
>   ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
>   ARC: dw2 unwind: switch to .eh_frame based unwinding
>
>  arch/arc/Makefile             |  2 ++
>  arch/arc/include/asm/elf.h    |  3 +--
>  arch/arc/kernel/entry.S       | 12 ------------
>  arch/arc/kernel/module.c      | 19 ++++++++-----------
>  arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
>  arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
>  6 files changed, 33 insertions(+), 42 deletions(-)
>
> --
> 2.7.4
>

[PATCH 0/3] ARC unwinder switch to .eh_frame

[Daniel Mentz]

Hi Vineet,

Thank you for your patches. I applied them, and verified that
unwinding works with code that is compiled into the kernel image as
well as kernel modules.
I confirmed that the .eh_frame section is present and that the
.debug_frame section is absent. I also verified that the file size of
the .ko files are small enough for our embedded platform and that
unnecessary sections like .debug_info, .debug_line, .debug_str etc.
are also absent.
Is there anything else you want me to test?
Thanks
Daniel


On Mon, Sep 19, 2016 at 2:49 PM, Vineet Gupta
<Vineet.Gupta1@synopsys.com> wrote:
> Hi Daniel,
>
> Give these a shot and let me know if they work fine for you.
> I'm working on some more improvements to unwinder which will follow
> a bit later.
>
> Thx,
> -Vineet
>
> Vineet Gupta (3):
>   ARC: module: support R_ARC_32_PCREL relocation
>   ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
>   ARC: dw2 unwind: switch to .eh_frame based unwinding
>
>  arch/arc/Makefile             |  2 ++
>  arch/arc/include/asm/elf.h    |  3 +--
>  arch/arc/kernel/entry.S       | 12 ------------
>  arch/arc/kernel/module.c      | 19 ++++++++-----------
>  arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
>  arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
>  6 files changed, 33 insertions(+), 42 deletions(-)
>
> --
> 2.7.4
>

Re: [PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> Hi Vineet,
> 
> Thank you for your patches. I applied them, and verified that
> unwinding works with code that is compiled into the kernel image as
> well as kernel modules.
> I confirmed that the .eh_frame section is present and that the
> .debug_frame section is absent. I also verified that the file size of
> the .ko files are small enough for our embedded platform and that
> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> are also absent.
> Is there anything else you want me to test?
> Thanks
> Daniel

Nope - that is it. Just wanted to make sure it is "field" tested :-)

Thx,
-Vineet


> On Mon, Sep 19, 2016 at 2:49 PM, Vineet Gupta
> <Vineet.Gupta1@synopsys.com> wrote:
>> Hi Daniel,
>>
>> Give these a shot and let me know if they work fine for you.
>> I'm working on some more improvements to unwinder which will follow
>> a bit later.
>>
>> Thx,
>> -Vineet
>>
>> Vineet Gupta (3):
>>   ARC: module: support R_ARC_32_PCREL relocation
>>   ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
>>   ARC: dw2 unwind: switch to .eh_frame based unwinding
>>
>>  arch/arc/Makefile             |  2 ++
>>  arch/arc/include/asm/elf.h    |  3 +--
>>  arch/arc/kernel/entry.S       | 12 ------------
>>  arch/arc/kernel/module.c      | 19 ++++++++-----------
>>  arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
>>  arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
>>  6 files changed, 33 insertions(+), 42 deletions(-)
>>
>> --
>> 2.7.4
>>
> 

[PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> Hi Vineet,
> 
> Thank you for your patches. I applied them, and verified that
> unwinding works with code that is compiled into the kernel image as
> well as kernel modules.
> I confirmed that the .eh_frame section is present and that the
> .debug_frame section is absent. I also verified that the file size of
> the .ko files are small enough for our embedded platform and that
> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> are also absent.
> Is there anything else you want me to test?
> Thanks
> Daniel

Nope - that is it. Just wanted to make sure it is "field" tested :-)

Thx,
-Vineet


> On Mon, Sep 19, 2016 at 2:49 PM, Vineet Gupta
> <Vineet.Gupta1@synopsys.com> wrote:
>> Hi Daniel,
>>
>> Give these a shot and let me know if they work fine for you.
>> I'm working on some more improvements to unwinder which will follow
>> a bit later.
>>
>> Thx,
>> -Vineet
>>
>> Vineet Gupta (3):
>>   ARC: module: support R_ARC_32_PCREL relocation
>>   ARC: dw2 unwind: factor CIE specifics for .eh_frame/.debug_frame
>>   ARC: dw2 unwind: switch to .eh_frame based unwinding
>>
>>  arch/arc/Makefile             |  2 ++
>>  arch/arc/include/asm/elf.h    |  3 +--
>>  arch/arc/kernel/entry.S       | 12 ------------
>>  arch/arc/kernel/module.c      | 19 ++++++++-----------
>>  arch/arc/kernel/unwind.c      | 24 +++++++++++++++++-------
>>  arch/arc/kernel/vmlinux.lds.S | 15 +++++----------
>>  6 files changed, 33 insertions(+), 42 deletions(-)
>>
>> --
>> 2.7.4
>>
> 

Re: [PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

Hi Daniel,

On 09/19/2016 11:13 PM, Vineet Gupta wrote:
> On 09/19/2016 06:21 PM, Daniel Mentz wrote:
>> > Hi Vineet,
>> > 
>> > Thank you for your patches. I applied them, and verified that
>> > unwinding works with code that is compiled into the kernel image as
>> > well as kernel modules.
>> > I confirmed that the .eh_frame section is present and that the
>> > .debug_frame section is absent. I also verified that the file size of
>> > the .ko files are small enough for our embedded platform and that
>> > unnecessary sections like .debug_info, .debug_line, .debug_str etc.
>> > are also absent.
>> > Is there anything else you want me to test?
>> > Thanks
>> > Daniel
> Nope - that is it. Just wanted to make sure it is "field" tested :-)
> 
> Thx,
> -Vineet

FYI - I've pushed some more changes to unwinding department so that we get
call-traces for memset/memcpy et al.

git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc.git  #for-next

-Vineet

[PATCH 0/3] ARC unwinder switch to .eh_frame

[Vineet Gupta]

Hi Daniel,

On 09/19/2016 11:13 PM, Vineet Gupta wrote:
> On 09/19/2016 06:21 PM, Daniel Mentz wrote:
>> > Hi Vineet,
>> > 
>> > Thank you for your patches. I applied them, and verified that
>> > unwinding works with code that is compiled into the kernel image as
>> > well as kernel modules.
>> > I confirmed that the .eh_frame section is present and that the
>> > .debug_frame section is absent. I also verified that the file size of
>> > the .ko files are small enough for our embedded platform and that
>> > unnecessary sections like .debug_info, .debug_line, .debug_str etc.
>> > are also absent.
>> > Is there anything else you want me to test?
>> > Thanks
>> > Daniel
> Nope - that is it. Just wanted to make sure it is "field" tested :-)
> 
> Thx,
> -Vineet

FYI - I've pushed some more changes to unwinding department so that we get
call-traces for memset/memcpy et al.

git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc.git  #for-next

-Vineet

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Vineet Gupta]

Hi Daniel,

On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> I confirmed that the .eh_frame section is present and that the
> .debug_frame section is absent. I also verified that the file size of
> the .ko files are small enough for our embedded platform and that
> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> are also absent.

BTW it seems with my latest set of patches, modules still have .debug_*.
Can you double check if your tree still has the interim patch which added a linker
script for modules to strip out .debug_*

http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html

I'm not planning to carry it and would prefer addressing the the root cause by
removing the -gdwarf-2 toggle. I've added that and pushed rebased series. Care to
take it for a respin please.

Thx,
-Vineet

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Vineet Gupta]

Hi Daniel,

On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> I confirmed that the .eh_frame section is present and that the
> .debug_frame section is absent. I also verified that the file size of
> the .ko files are small enough for our embedded platform and that
> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> are also absent.

BTW it seems with my latest set of patches, modules still have .debug_*.
Can you double check if your tree still has the interim patch which added a linker
script for modules to strip out .debug_*

http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html

I'm not planning to carry it and would prefer addressing the the root cause by
removing the -gdwarf-2 toggle. I've added that and pushed rebased series. Care to
take it for a respin please.

Thx,
-Vineet

Re: modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Thu, Sep 22, 2016 at 1:59 PM, Vineet Gupta
<Vineet.Gupta1@synopsys.com> wrote:
> Hi Daniel,
>
> On 09/19/2016 06:21 PM, Daniel Mentz wrote:
>> I confirmed that the .eh_frame section is present and that the
>> .debug_frame section is absent. I also verified that the file size of
>> the .ko files are small enough for our embedded platform and that
>> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
>> are also absent.
>
> BTW it seems with my latest set of patches, modules still have .debug_*.
> Can you double check if your tree still has the interim patch which added a linker
> script for modules to strip out .debug_*
>
> http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html

Hi Vineet,

Sorry, that was a misunderstanding. Buildroot routinely runs the strip
command on .ko files before installing them on the target. I was only
looking at the .ko files *after* running the strip command. No, the
interim patch was not in my tree.

I confirmed that your commit "ARC: dw2 unwind: don't force dwarf 2" is
indeed necessary to suppress the .debug_* sections when
CONFIG_DEBUG_INFO is off. But again, we're stripping .ko files anyways
before installing.

> I'm not planning to carry it and would prefer addressing the the root cause by
> removing the -gdwarf-2 toggle. I've added that and pushed rebased series. Care to
> take it for a respin please.

I downloaded your latest commit
e47305af57d7eedc10b4720e604d669b10c69e3b and verified that stack
traces are properly displayed for code inside kernel modules as well
as vmlinux. I also called memcpy() on some bad address and got a
proper stack trace that involved memcpy().

I conclude that unwinding works for us.

Thank You
 Daniel

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Thu, Sep 22, 2016 at 1:59 PM, Vineet Gupta
<Vineet.Gupta1@synopsys.com> wrote:
> Hi Daniel,
>
> On 09/19/2016 06:21 PM, Daniel Mentz wrote:
>> I confirmed that the .eh_frame section is present and that the
>> .debug_frame section is absent. I also verified that the file size of
>> the .ko files are small enough for our embedded platform and that
>> unnecessary sections like .debug_info, .debug_line, .debug_str etc.
>> are also absent.
>
> BTW it seems with my latest set of patches, modules still have .debug_*.
> Can you double check if your tree still has the interim patch which added a linker
> script for modules to strip out .debug_*
>
> http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html

Hi Vineet,

Sorry, that was a misunderstanding. Buildroot routinely runs the strip
command on .ko files before installing them on the target. I was only
looking at the .ko files *after* running the strip command. No, the
interim patch was not in my tree.

I confirmed that your commit "ARC: dw2 unwind: don't force dwarf 2" is
indeed necessary to suppress the .debug_* sections when
CONFIG_DEBUG_INFO is off. But again, we're stripping .ko files anyways
before installing.

> I'm not planning to carry it and would prefer addressing the the root cause by
> removing the -gdwarf-2 toggle. I've added that and pushed rebased series. Care to
> take it for a respin please.

I downloaded your latest commit
e47305af57d7eedc10b4720e604d669b10c69e3b and verified that stack
traces are properly displayed for code inside kernel modules as well
as vmlinux. I also called memcpy() on some bad address and got a
proper stack trace that involved memcpy().

I conclude that unwinding works for us.

Thank You
 Daniel

Re: modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Alexey Brodkin]

Hi Daniel,

On Thu, 2016-09-22 at 15:37 -0700, Daniel Mentz wrote:
> On Thu, Sep 22, 2016 at 1:59 PM, Vineet Gupta
> <Vineet.Gupta1@synopsys.com> wrote:
> > 
> > Hi Daniel,
> > 
> > On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> > > 
> > > I confirmed that the .eh_frame section is present and that the
> > > .debug_frame section is absent. I also verified that the file size of
> > > the .ko files are small enough for our embedded platform and that
> > > unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> > > are also absent.
> > 
> > BTW it seems with my latest set of patches, modules still have .debug_*.
> > Can you double check if your tree still has the interim patch which added a linker
> > script for modules to strip out .debug_*
> > 
> > http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html
> 
> Hi Vineet,
> 
> Sorry, that was a misunderstanding. Buildroot routinely runs the strip
> command on .ko files before installing them on the target. I was only
> looking at the .ko files *after* running the strip command. No, the
> interim patch was not in my tree.

Well are you sure buildroot really touches modules in Linux kernel build folder?
Buildroot just runs a simple "make" command in "output/build/linux-x.y".

And only on installation step Buildroot strips binaries in "output/target" folder.
Moreover starting from that commit
https://git.buildroot.net/buildroot/commit/?id=10c4d27aef4dca01572cfc8146cbfd194a1a85e4
even on Linux installation step Buildroot reuses kernel's module stripping infrastructure
but again that happens only on target.

Just in case that's what I see when building MSDOSFS as module.

In build folder:
----------------------------->8-------------------------------
arc-linux-readelf -S build/linux-4.7.3/fs/fat/msdos.ko
There are 38 section headers, starting at offset 0x2a630:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .note.gnu.build-i NOTE            00000000 000034 000024 00   A  0   0  4
  [ 2] .text             PROGBITS        00000000 000058 0013a8 00  AX  0   0  4
  [ 3] .rela.text        RELA            00000000 01c774 000600 0c   I 35   2  4
  [ 4] .init.text        PROGBITS        00000000 001400 000010 00  AX  0   0  4
  [ 5] .rela.init.text   RELA            00000000 01cd74 000018 0c   I 35   4  4
  [ 6] .exit.text        PROGBITS        00000000 001410 000010 00  AX  0   0  4
  [ 7] .rela.exit.text   RELA            00000000 01cd8c 000018 0c   I 35   6  4
  [ 8] .rodata           PROGBITS        00000000 001440 000100 00   A  0   0 64
  [ 9] .rela.rodata      RELA            00000000 01cda4 000078 0c   I 35   8  4
  [10] .modinfo          PROGBITS        00000000 001540 000090 00   A  0   0  4
  [11] .rodata.str1.4    PROGBITS        00000000 0015d0 000030 01 AMS  0   0  4
  [12] .data             PROGBITS        00000000 001600 00002c 00  WA  0   0  4
  [13] .rela.data        RELA            00000000 01ce1c 000030 0c   I 35  12  4
  [14] .gnu.linkonce.thi PROGBITS        00000000 001640 000140 00  WA  0   0 64
  [15] .rela.gnu.linkonc RELA            00000000 01ce4c 00000c 0c   I 35  14  4
  [16] .tdata            PROGBITS        00000000 001780 000000 00 WAT  0   0  1
  [17] .tbss             NOBITS          00000000 001780 000000 00 WAT  0   0  1
  [18] .bss              NOBITS          00000000 001780 000000 00  WA  0   0  1
  [19] .comment          PROGBITS        00000000 001780 000078 01  MS  0   0  1
  [20] .note.GNU-stack   PROGBITS        00000000 0017f8 000000 00      0   0  1
  [21] .debug_aranges    PROGBITS        00000000 0017f8 000048 00      0   0  1
  [22] .rela.debug_arang RELA            00000000 01ce58 00003c 0c   I 35  21  4
  [23] .debug_info       PROGBITS        00000000 001840 00eaa9 00      0   0  1
  [24] .rela.debug_info  RELA            00000000 01ce94 00a53c 0c   I 35  23  4
  [25] .debug_abbrev     PROGBITS        00000000 0102e9 0008b3 00      0   0  1
  [26] .debug_line       PROGBITS        00000000 010b9c 001d4d 00      0   0  1
  [27] .rela.debug_line  RELA            00000000 0273d0 001818 0c   I 35  26  4
  [28] .debug_frame      PROGBITS        00000000 0128ec 0002d8 00      0   0  4
  [29] .rela.debug_frame RELA            00000000 028be8 000168 0c   I 35  28  4
  [30] .debug_str        PROGBITS        00000000 012bc4 008485 01  MS  0   0  1
  [31] .debug_loc        PROGBITS        00000000 01b049 000b49 00      0   0  1
  [32] .rela.debug_loc   RELA            00000000 028d50 001308 0c   I 35  31  4
  [33] .debug_ranges     PROGBITS        00000000 01bb92 0001f8 00      0   0  1
  [34] .rela.debug_range RELA            00000000 02a058 000480 0c   I 35  33  4
  [35] .symtab           SYMTAB          00000000 01bd8c 0005e0 10     36  53  4
  [36] .strtab           STRTAB          00000000 01c36c 000407 00      0   0  1
  [37] .shstrtab         STRTAB          00000000 02a4d8 000157 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  p (processor specific)
----------------------------->8-------------------------------

On target:
----------------------------->8-------------------------------
arc-linux-readelf -S target/lib/modules/4.7.3/kernel/fs/fat/msdos.ko 
There are 24 section headers, starting at offset 0x28e0:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .note.gnu.build-i NOTE            00000000 000034 000024 00   A  0   0  4
  [ 2] .text             PROGBITS        00000000 000058 0013a8 00  AX  0   0  4
  [ 3] .rela.text        RELA            00000000 002128 000600 0c   I 21   2  4
  [ 4] .init.text        PROGBITS        00000000 001400 000010 00  AX  0   0  4
  [ 5] .rela.init.text   RELA            00000000 002728 000018 0c   I 21   4  4
  [ 6] .exit.text        PROGBITS        00000000 001410 000010 00  AX  0   0  4
  [ 7] .rela.exit.text   RELA            00000000 002740 000018 0c   I 21   6  4
  [ 8] .rodata           PROGBITS        00000000 001440 000100 00   A  0   0 64
  [ 9] .rela.rodata      RELA            00000000 002758 000078 0c   I 21   8  4
  [10] .modinfo          PROGBITS        00000000 001540 000090 00   A  0   0  4
  [11] .rodata.str1.4    PROGBITS        00000000 0015d0 000030 01 AMS  0   0  4
  [12] .data             PROGBITS        00000000 001600 00002c 00  WA  0   0  4
  [13] .rela.data        RELA            00000000 0027d0 000030 0c   I 21  12  4
  [14] .gnu.linkonce.thi PROGBITS        00000000 001640 000140 00  WA  0   0 64
  [15] .rela.gnu.linkonc RELA            00000000 002800 00000c 0c   I 21  14  4
  [16] .tdata            PROGBITS        00000000 001780 000000 00 WAT  0   0  1
  [17] .tbss             NOBITS          00000000 001780 000000 00 WAT  0   0  1
  [18] .bss              NOBITS          00000000 001780 000000 00  WA  0   0  1
  [19] .comment          PROGBITS        00000000 001780 000078 01  MS  0   0  1
  [20] .note.GNU-stack   PROGBITS        00000000 0017f8 000000 00      0   0  1
  [21] .symtab           SYMTAB          00000000 0017f8 000540 10     22  43  4
  [22] .strtab           STRTAB          00000000 001d38 0003ed 00      0   0  1
  [23] .shstrtab         STRTAB          00000000 00280c 0000d3 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  p (processor specific)
----------------------------->8-------------------------------

-Alexey

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Alexey Brodkin]

Hi Daniel,

On Thu, 2016-09-22@15:37 -0700, Daniel Mentz wrote:
> On Thu, Sep 22, 2016 at 1:59 PM, Vineet Gupta
> <Vineet.Gupta1@synopsys.com> wrote:
> > 
> > Hi Daniel,
> > 
> > On 09/19/2016 06:21 PM, Daniel Mentz wrote:
> > > 
> > > I confirmed that the .eh_frame section is present and that the
> > > .debug_frame section is absent. I also verified that the file size of
> > > the .ko files are small enough for our embedded platform and that
> > > unnecessary sections like .debug_info, .debug_line, .debug_str etc.
> > > are also absent.
> > 
> > BTW it seems with my latest set of patches, modules still have .debug_*.
> > Can you double check if your tree still has the interim patch which added a linker
> > script for modules to strip out .debug_*
> > 
> > http://lists.infradead.org/pipermail/linux-snps-arc/2016-September/001483.html
> 
> Hi Vineet,
> 
> Sorry, that was a misunderstanding. Buildroot routinely runs the strip
> command on .ko files before installing them on the target. I was only
> looking at the .ko files *after* running the strip command. No, the
> interim patch was not in my tree.

Well are you sure buildroot really touches modules in Linux kernel build folder?
Buildroot just runs a simple "make" command in "output/build/linux-x.y".

And only on installation step Buildroot strips binaries in "output/target" folder.
Moreover starting from that commit
https://git.buildroot.net/buildroot/commit/?id=10c4d27aef4dca01572cfc8146cbfd194a1a85e4
even on Linux installation step Buildroot reuses kernel's module stripping infrastructure
but again that happens only on target.

Just in case that's what I see when building MSDOSFS as module.

In build folder:
----------------------------->8-------------------------------
arc-linux-readelf -S build/linux-4.7.3/fs/fat/msdos.ko
There are 38 section headers, starting at offset 0x2a630:

Section Headers:
? [Nr] Name??????????????Type????????????Addr?????Off????Size???ES Flg Lk Inf Al
? [ 0]???????????????????NULL????????????00000000 000000 000000 00??????0???0??0
? [ 1] .note.gnu.build-i NOTE????????????00000000 000034 000024 00???A??0???0??4
? [ 2] .text?????????????PROGBITS????????00000000 000058 0013a8 00??AX??0???0??4
? [ 3] .rela.text????????RELA????????????00000000 01c774 000600 0c???I 35???2??4
? [ 4] .init.text????????PROGBITS????????00000000 001400 000010 00??AX??0???0??4
? [ 5] .rela.init.text???RELA????????????00000000 01cd74 000018 0c???I 35???4??4
? [ 6] .exit.text????????PROGBITS????????00000000 001410 000010 00??AX??0???0??4
? [ 7] .rela.exit.text???RELA????????????00000000 01cd8c 000018 0c???I 35???6??4
? [ 8] .rodata???????????PROGBITS????????00000000 001440 000100 00???A??0???0 64
? [ 9] .rela.rodata??????RELA????????????00000000 01cda4 000078 0c???I 35???8??4
? [10] .modinfo??????????PROGBITS????????00000000 001540 000090 00???A??0???0??4
? [11] .rodata.str1.4????PROGBITS????????00000000 0015d0 000030 01 AMS??0???0??4
? [12] .data?????????????PROGBITS????????00000000 001600 00002c 00??WA??0???0??4
? [13] .rela.data????????RELA????????????00000000 01ce1c 000030 0c???I 35??12??4
? [14] .gnu.linkonce.thi PROGBITS????????00000000 001640 000140 00??WA??0???0 64
? [15] .rela.gnu.linkonc RELA????????????00000000 01ce4c 00000c 0c???I 35??14??4
? [16] .tdata????????????PROGBITS????????00000000 001780 000000 00 WAT??0???0??1
? [17] .tbss?????????????NOBITS??????????00000000 001780 000000 00 WAT??0???0??1
? [18] .bss??????????????NOBITS??????????00000000 001780 000000 00??WA??0???0??1
? [19] .comment??????????PROGBITS????????00000000 001780 000078 01??MS??0???0??1
? [20] .note.GNU-stack???PROGBITS????????00000000 0017f8 000000 00??????0???0??1
? [21] .debug_aranges????PROGBITS????????00000000 0017f8 000048 00??????0???0??1
? [22] .rela.debug_arang RELA????????????00000000 01ce58 00003c 0c???I 35??21??4
? [23] .debug_info???????PROGBITS????????00000000 001840 00eaa9 00??????0???0??1
? [24] .rela.debug_info??RELA????????????00000000 01ce94 00a53c 0c???I 35??23??4
? [25] .debug_abbrev?????PROGBITS????????00000000 0102e9 0008b3 00??????0???0??1
? [26] .debug_line???????PROGBITS????????00000000 010b9c 001d4d 00??????0???0??1
? [27] .rela.debug_line??RELA????????????00000000 0273d0 001818 0c???I 35??26??4
? [28] .debug_frame??????PROGBITS????????00000000 0128ec 0002d8 00??????0???0??4
? [29] .rela.debug_frame RELA????????????00000000 028be8 000168 0c???I 35??28??4
? [30] .debug_str????????PROGBITS????????00000000 012bc4 008485 01??MS??0???0??1
? [31] .debug_loc????????PROGBITS????????00000000 01b049 000b49 00??????0???0??1
? [32] .rela.debug_loc???RELA????????????00000000 028d50 001308 0c???I 35??31??4
? [33] .debug_ranges?????PROGBITS????????00000000 01bb92 0001f8 00??????0???0??1
? [34] .rela.debug_range RELA????????????00000000 02a058 000480 0c???I 35??33??4
? [35] .symtab???????????SYMTAB??????????00000000 01bd8c 0005e0 10?????36??53??4
? [36] .strtab???????????STRTAB??????????00000000 01c36c 000407 00??????0???0??1
? [37] .shstrtab?????????STRTAB??????????00000000 02a4d8 000157 00??????0???0??1
Key to Flags:
? W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
? L (link order), O (extra OS processing required), G (group), T (TLS),
? C (compressed), x (unknown), o (OS specific), E (exclude),
? p (processor specific)
----------------------------->8-------------------------------

On target:
----------------------------->8-------------------------------
arc-linux-readelf -S target/lib/modules/4.7.3/kernel/fs/fat/msdos.ko?
There are 24 section headers, starting at offset 0x28e0:

Section Headers:
? [Nr] Name??????????????Type????????????Addr?????Off????Size???ES Flg Lk Inf Al
? [ 0]???????????????????NULL????????????00000000 000000 000000 00??????0???0??0
? [ 1] .note.gnu.build-i NOTE????????????00000000 000034 000024 00???A??0???0??4
? [ 2] .text?????????????PROGBITS????????00000000 000058 0013a8 00??AX??0???0??4
? [ 3] .rela.text????????RELA????????????00000000 002128 000600 0c???I 21???2??4
? [ 4] .init.text????????PROGBITS????????00000000 001400 000010 00??AX??0???0??4
? [ 5] .rela.init.text???RELA????????????00000000 002728 000018 0c???I 21???4??4
? [ 6] .exit.text????????PROGBITS????????00000000 001410 000010 00??AX??0???0??4
? [ 7] .rela.exit.text???RELA????????????00000000 002740 000018 0c???I 21???6??4
? [ 8] .rodata???????????PROGBITS????????00000000 001440 000100 00???A??0???0 64
? [ 9] .rela.rodata??????RELA????????????00000000 002758 000078 0c???I 21???8??4
? [10] .modinfo??????????PROGBITS????????00000000 001540 000090 00???A??0???0??4
? [11] .rodata.str1.4????PROGBITS????????00000000 0015d0 000030 01 AMS??0???0??4
? [12] .data?????????????PROGBITS????????00000000 001600 00002c 00??WA??0???0??4
? [13] .rela.data????????RELA????????????00000000 0027d0 000030 0c???I 21??12??4
? [14] .gnu.linkonce.thi PROGBITS????????00000000 001640 000140 00??WA??0???0 64
? [15] .rela.gnu.linkonc RELA????????????00000000 002800 00000c 0c???I 21??14??4
? [16] .tdata????????????PROGBITS????????00000000 001780 000000 00 WAT??0???0??1
? [17] .tbss?????????????NOBITS??????????00000000 001780 000000 00 WAT??0???0??1
? [18] .bss??????????????NOBITS??????????00000000 001780 000000 00??WA??0???0??1
? [19] .comment??????????PROGBITS????????00000000 001780 000078 01??MS??0???0??1
? [20] .note.GNU-stack???PROGBITS????????00000000 0017f8 000000 00??????0???0??1
? [21] .symtab???????????SYMTAB??????????00000000 0017f8 000540 10?????22??43??4
? [22] .strtab???????????STRTAB??????????00000000 001d38 0003ed 00??????0???0??1
? [23] .shstrtab?????????STRTAB??????????00000000 00280c 0000d3 00??????0???0??1
Key to Flags:
? W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
? L (link order), O (extra OS processing required), G (group), T (TLS),
? C (compressed), x (unknown), o (OS specific), E (exclude),
? p (processor specific)
----------------------------->8-------------------------------

-Alexey

Re: modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
<Alexey.Brodkin@synopsys.com> wrote:
> On Thu, 2016-09-22 at 15:37 -0700, Daniel Mentz wrote:
>> Sorry, that was a misunderstanding. Buildroot routinely runs the strip
>> command on .ko files before installing them on the target. I was only
>> looking at the .ko files *after* running the strip command. No, the
>> interim patch was not in my tree.
>
> Well are you sure buildroot really touches modules in Linux kernel build folder?
> Buildroot just runs a simple "make" command in "output/build/linux-x.y".

Sorry, that was phrased badly. Buildroot does not touch the modules in
the Linux kernel build folder. Modules are stripped in the target
directory as you described.

> And only on installation step Buildroot strips binaries in "output/target" folder.
> Moreover starting from that commit
> https://git.buildroot.net/buildroot/commit/?id=10c4d27aef4dca01572cfc8146cbfd194a1a85e4
> even on Linux installation step Buildroot reuses kernel's module stripping infrastructure
> but again that happens only on target.

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
<Alexey.Brodkin@synopsys.com> wrote:
> On Thu, 2016-09-22@15:37 -0700, Daniel Mentz wrote:
>> Sorry, that was a misunderstanding. Buildroot routinely runs the strip
>> command on .ko files before installing them on the target. I was only
>> looking at the .ko files *after* running the strip command. No, the
>> interim patch was not in my tree.
>
> Well are you sure buildroot really touches modules in Linux kernel build folder?
> Buildroot just runs a simple "make" command in "output/build/linux-x.y".

Sorry, that was phrased badly. Buildroot does not touch the modules in
the Linux kernel build folder. Modules are stripped in the target
directory as you described.

> And only on installation step Buildroot strips binaries in "output/target" folder.
> Moreover starting from that commit
> https://git.buildroot.net/buildroot/commit/?id=10c4d27aef4dca01572cfc8146cbfd194a1a85e4
> even on Linux installation step Buildroot reuses kernel's module stripping infrastructure
> but again that happens only on target.

Re: modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Alexey Brodkin]

Hi Daniel,

On Fri, 2016-09-23 at 18:04 -0700, Daniel Mentz wrote:
> On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
> <Alexey.Brodkin@synopsys.com> wrote:
> > 
> > On Thu, 2016-09-22 at 15:37 -0700, Daniel Mentz wrote:
> > > 
> > > Sorry, that was a misunderstanding. Buildroot routinely runs the strip
> > > command on .ko files before installing them on the target. I was only
> > > looking at the .ko files *after* running the strip command. No, the
> > > interim patch was not in my tree.
> > 
> > Well are you sure buildroot really touches modules in Linux kernel build folder?
> > Buildroot just runs a simple "make" command in "output/build/linux-x.y".
> 
> Sorry, that was phrased badly. Buildroot does not touch the modules in
> the Linux kernel build folder. Modules are stripped in the target
> directory as you described.

So every is as expected now for you or there're still thing you don't like?

-Alexey

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Alexey Brodkin]

Hi Daniel,

On Fri, 2016-09-23@18:04 -0700, Daniel Mentz wrote:
> On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
> <Alexey.Brodkin@synopsys.com> wrote:
> > 
> > On Thu, 2016-09-22@15:37 -0700, Daniel Mentz wrote:
> > > 
> > > Sorry, that was a misunderstanding. Buildroot routinely runs the strip
> > > command on .ko files before installing them on the target. I was only
> > > looking at the .ko files *after* running the strip command. No, the
> > > interim patch was not in my tree.
> > 
> > Well are you sure buildroot really touches modules in Linux kernel build folder?
> > Buildroot just runs a simple "make" command in "output/build/linux-x.y".
> 
> Sorry, that was phrased badly. Buildroot does not touch the modules in
> the Linux kernel build folder. Modules are stripped in the target
> directory as you described.

So every is as expected now for you or there're still thing you don't like?

-Alexey

Re: modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Mon, Sep 26, 2016 at 5:38 AM, Alexey Brodkin
<Alexey.Brodkin@synopsys.com> wrote:
> On Fri, 2016-09-23 at 18:04 -0700, Daniel Mentz wrote:
>> On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
>> <Alexey.Brodkin@synopsys.com> wrote:
>> >
>> > On Thu, 2016-09-22 at 15:37 -0700, Daniel Mentz wrote:
>> > >
>> > > Sorry, that was a misunderstanding. Buildroot routinely runs the strip
>> > > command on .ko files before installing them on the target. I was only
>> > > looking at the .ko files *after* running the strip command. No, the
>> > > interim patch was not in my tree.
>> >
>> > Well are you sure buildroot really touches modules in Linux kernel build folder?
>> > Buildroot just runs a simple "make" command in "output/build/linux-x.y".
>>
>> Sorry, that was phrased badly. Buildroot does not touch the modules in
>> the Linux kernel build folder. Modules are stripped in the target
>> directory as you described.
>
> So every is as expected now for you or there're still thing you don't like?

Yes, everything works as expected now. Thank you for Synposys' support
with this issue.

modules still have .debug_* (was Re: [PATCH 0/3] ARC unwinder switch to .eh_frame)

[Daniel Mentz]

On Mon, Sep 26, 2016 at 5:38 AM, Alexey Brodkin
<Alexey.Brodkin@synopsys.com> wrote:
> On Fri, 2016-09-23@18:04 -0700, Daniel Mentz wrote:
>> On Fri, Sep 23, 2016 at 3:38 AM, Alexey Brodkin
>> <Alexey.Brodkin@synopsys.com> wrote:
>> >
>> > On Thu, 2016-09-22@15:37 -0700, Daniel Mentz wrote:
>> > >
>> > > Sorry, that was a misunderstanding. Buildroot routinely runs the strip
>> > > command on .ko files before installing them on the target. I was only
>> > > looking at the .ko files *after* running the strip command. No, the
>> > > interim patch was not in my tree.
>> >
>> > Well are you sure buildroot really touches modules in Linux kernel build folder?
>> > Buildroot just runs a simple "make" command in "output/build/linux-x.y".
>>
>> Sorry, that was phrased badly. Buildroot does not touch the modules in
>> the Linux kernel build folder. Modules are stripped in the target
>> directory as you described.
>
> So every is as expected now for you or there're still thing you don't like?

Yes, everything works as expected now. Thank you for Synposys' support
with this issue.