[PATCH 07/17] ARC: dw2 unwind: Refactor the FDE lookup table (eh_frame_header) code

From: Vineet Gupta
Date: Thu Dec 03 2015 - 07:43:57 EST

- Reduce 1 level of indenatation
- Use struct members to identify what's going on !
- Nothing semantical

Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
arch/arc/kernel/unwind.c | 175 ++++++++++++++++++++++-------------------------
1 file changed, 83 insertions(+), 92 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index f57a0d50185c..9f5ed6873c52 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -101,6 +101,20 @@ static const struct {
typedef unsigned long uleb128_t;
typedef signed long sleb128_t;

+struct eh_frame_hdr_table_entry {
+ unsigned long start, fde;
+};
+
+struct eh_frame_header {
+ u8 version;
+ u8 eh_frame_ptr_enc;
+ u8 fde_count_enc;
+ u8 table_enc;
+ unsigned long eh_frame_ptr;
+ unsigned int fde_count;
+ struct eh_frame_hdr_table_entry table[];
+} __attribute__ ((__packed__));
+
static struct unwind_table {
struct {
unsigned long pc;
@@ -108,7 +122,7 @@ static struct unwind_table {
} core, init;
const void *address;
unsigned long size;
- const unsigned char *header;
+ struct eh_frame_header *header;
unsigned long hdrsz;
struct unwind_table *link;
const char *name;
@@ -185,7 +199,7 @@ static void init_unwind_table(struct unwind_table *table, const char *name,

table->hdrsz = header_size;
smp_wmb();
- table->header = header_start;
+ table->header = (struct eh_frame_header *)header_start;
table->link = NULL;
table->name = name;
}
@@ -202,10 +216,6 @@ static const u32 bad_cie, not_fde;
static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
static signed fde_pointer_type(const u32 *cie);

-struct eh_frame_hdr_table_entry {
- unsigned long start, fde;
-};
-
static int cmp_eh_frame_hdr_table_entries(const void *p1, const void *p2)
{
const struct eh_frame_hdr_table_entry *e1 = p1;
@@ -235,15 +245,7 @@ static void __init setup_unwind_table(struct unwind_table *table,
unsigned long tableSize = table->size, hdrSize;
unsigned n;
const u32 *fde;
- struct {
- u8 version;
- u8 eh_frame_ptr_enc;
- u8 fde_count_enc;
- u8 table_enc;
- unsigned long eh_frame_ptr;
- unsigned int fde_count;
- struct eh_frame_hdr_table_entry table[];
- } __attribute__ ((__packed__)) *header;
+ struct eh_frame_header *header;

if (table->header)
return;
@@ -326,7 +328,7 @@ static void __init setup_unwind_table(struct unwind_table *table,

table->hdrsz = hdrSize;
smp_wmb();
- table->header = (const void *)header;
+ table->header = header;
}

static void *__init balloc(unsigned long sz)
@@ -871,6 +873,8 @@ int arc_unwind(struct unwind_frame_info *frame)
struct unwind_state state;
unsigned long *fptr;
unsigned long addr;
+ struct eh_frame_header *hdr;
+ unsigned long hdrEntrySz;

unw_debug("\nUNWIND FRAME: -------------------------------------\n");
unw_debug("PC\t\t: 0x%lx %pS\nr31 [BLINK]\t: 0x%lx %pS\nr28 [SP]\t: 0x%lx\nr27 [FP]\t: 0x%lx\n",
@@ -892,88 +896,75 @@ int arc_unwind(struct unwind_frame_info *frame)
#endif

table = find_table(pc);
- if (table != NULL) {
- const u8 *hdr = table->header;
- unsigned long tableSize;
-
- smp_rmb();
- if (hdr && hdr[0] == 1) {
- switch (hdr[3] & DW_EH_PE_FORM) {
- case DW_EH_PE_native:
- tableSize = sizeof(unsigned long);
- break;
- case DW_EH_PE_data2:
- tableSize = 2;
- break;
- case DW_EH_PE_data4:
- tableSize = 4;
- break;
- case DW_EH_PE_data8:
- tableSize = 8;
- break;
- default:
- tableSize = 0;
- break;
- }
- ptr = hdr + 4;
- end = hdr + table->hdrsz;
- if (tableSize && read_pointer(&ptr, end, hdr[1])
- == (unsigned long)table->address
- && (i = read_pointer(&ptr, end, hdr[2])) > 0
- && i == (end - ptr) / (2 * tableSize)
- && !((end - ptr) % (2 * tableSize))) {
- do {
- const u8 *cur =
- ptr + (i / 2) * (2 * tableSize);
-
- startLoc = read_pointer(&cur,
- cur + tableSize,
- hdr[3]);
- if (pc < startLoc)
- i /= 2;
- else {
- ptr = cur - tableSize;
- i = (i + 1) / 2;
- }
- } while (startLoc && i > 1);
- if (i == 1
- && (startLoc = read_pointer(&ptr,
- ptr + tableSize,
- hdr[3])) != 0
- && pc >= startLoc)
- fde = (void *)read_pointer(&ptr,
- ptr +
- tableSize,
- hdr[3]);
- }
+ if (table == NULL)
+ return -EINVAL;
+
+ hdr = table->header;
+
+ smp_rmb();
+ if (hdr && hdr->version == 1) {
+ switch (hdr->table_enc & DW_EH_PE_FORM) {
+ case DW_EH_PE_native:
+ hdrEntrySz = sizeof(unsigned long);
+ break;
+ case DW_EH_PE_data2:
+ hdrEntrySz = 2;
+ break;
+ case DW_EH_PE_data4:
+ hdrEntrySz = 4;
+ break;
+ case DW_EH_PE_data8:
+ hdrEntrySz = 8;
+ break;
+ default:
+ hdrEntrySz = 0;
+ break;
}

- if (fde != NULL) {
- cie = cie_for_fde(fde, table);
- ptr = (const u8 *)(fde + 2);
- if (cie != NULL
- && cie != &bad_cie
- && cie != &not_fde
- && (ptrType = fde_pointer_type(cie)) >= 0
- && read_pointer(&ptr,
- (const u8 *)(fde + 1) + *fde,
- ptrType) == startLoc) {
- if (!(ptrType & DW_EH_PE_indirect))
- ptrType &=
- DW_EH_PE_FORM | DW_EH_PE_signed;
- endLoc =
- startLoc + read_pointer(&ptr,
- (const u8 *)(fde +
- 1) +
- *fde, ptrType);
- if (pc >= endLoc) {
- fde = NULL;
- cie = NULL;
+ ptr = (const u8*)(hdr->eh_frame_ptr);
+ end = (const u8*)(hdr) + table->hdrsz;
+ if (hdrEntrySz
+ && read_pointer(&ptr, end, hdr->eh_frame_ptr_enc) /* eh_frame_ptr */
+ == (unsigned long)table->address
+ && (i = read_pointer(&ptr, end, hdr->fde_count_enc)) > 0 /* fde_count */
+ && i == (end - ptr) / (2 * hdrEntrySz)
+ && !((end - ptr) % (2 * hdrEntrySz))) {
+ do {
+ const u8 *cur = ptr + (i / 2) * (2 * hdrEntrySz);
+
+ startLoc = read_pointer(&cur, cur + hdrEntrySz, hdr->table_enc);
+ if (pc < startLoc)
+ i /= 2;
+ else {
+ ptr = cur - hdrEntrySz;
+ i = (i + 1) / 2;
}
- } else {
+ } while (startLoc && i > 1);
+ if (i == 1
+ && (startLoc = read_pointer(&ptr, ptr + hdrEntrySz, hdr->table_enc)) != 0
+ && pc >= startLoc)
+ fde = (void *)read_pointer(&ptr, ptr + hdrEntrySz, hdr->table_enc);
+ }
+ }
+
+ if (fde != NULL) {
+ cie = cie_for_fde(fde, table);
+ ptr = (const u8 *)(fde + 2);
+ if (cie != NULL
+ && cie != &bad_cie
+ && cie != &not_fde
+ && (ptrType = fde_pointer_type(cie)) >= 0
+ && read_pointer(&ptr, (const u8 *)(fde + 1) + *fde, ptrType) == startLoc) {
+ if (!(ptrType & DW_EH_PE_indirect))
+ ptrType &= DW_EH_PE_FORM | DW_EH_PE_signed;
+ endLoc = startLoc + read_pointer(&ptr, (const u8 *)(fde + 1) + *fde, ptrType);
+ if (pc >= endLoc) {
fde = NULL;
cie = NULL;
}
+ } else {
+ fde = NULL;
+ cie = NULL;
}
}
if (cie != NULL) {
--
1.9.1

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