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[PATCH 5/8] [PowerPC] Fix access to VSCR in linux targets
- From: Pedro Franco de Carvalho <pedromfc at linux dot vnet dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Date: Thu, 10 May 2018 16:58:37 -0300
- Subject: [PATCH 5/8] [PowerPC] Fix access to VSCR in linux targets
- References: <20180510195840.17734-1-pedromfc@linux.vnet.ibm.com>
The 4-byte VSCR register is found inside a 16-byte field in the regset
returned by ptrace and in core files. The position of VSCR depends on
the endianess of the target, which was previously assumed to be
big-endian for the purpose of getting VSCR. This patch removes this
assumption to fix access to VSCR in little-endian mode.
gdb/ChangeLog:
yyyy-mm-dd Pedro Franco de Carvalho <pedromfc@linux.vnet.ibm.com>
* ppc-linux-tdep.c (ppc_linux_collect_vrregset): New function.
(ppc_linux_vrregset) : New function.
(ppc32_le_linux_vrregmap, ppc32_be_linux_vrregmap)
(ppc32_le_linux_vrregset, ppc32_be_linux_vrregset): New globals.
(ppc32_linux_vrregset): Remove.
(ppc_linux_iterate_over_regset_sections): Call ppc_linux_vrregset
and use result instead of ppc32_linux_vrregset.
* ppc-linux-tdep.h (ppc_linux_vrregset): New declaration.
* ppc-linux-nat.c: Include regset.h.
(gdb_vrregset_t): Adjust comment to account for little-endian
mode.
(supply_vrregset, fill_vrregset): Remove.
(fetch_altivec_register, store_altivec_register): Remove.
(fetch_altivec_registers): Add regno parameter. Get regset using
ppc_linux_vrregset. Use regset to supply registers.
(store_altivec_registers): Add regno parameter. Get regset using
ppc_linux_vrregset. Use regset to collect registers.
(fetch_register): Call fetch_altivec_registers instead of
fetch_altivec_register.
(store_register): Call store_altivec_registers instead of
store_altivec_register.
(fetch_ppc_registers): Call fetch_altivec_registers with -1 for
the new regno parameter.
(store_ppc_registers): Call store_altivec_registers with -1 for
the new regno parameter.
gdb/gdbserver/ChangeLog:
yyyy-mm-dd Pedro Franco de Carvalho <pedromfc@linux.vnet.ibm.com>
* linux-ppc-low.c (ppc_fill_vrregset): Add vscr_offset variable.
Set vscr_offset to 0 in little-endian mode and 12 in big-endian
mode. Call collect_register_by_name with vscr using
vscr_offset. Zero-pad vscr and vrsave fields in collector buffer.
(ppc_store_vrregset): Add and set vscr_offset variable as in
ppc_fill_vrregset. Call supply_register_by_name with vscr using
vscr_offset.
---
gdb/gdbserver/linux-ppc-low.c | 19 +++++-
gdb/ppc-linux-nat.c | 153 +++++++-----------------------------------
gdb/ppc-linux-tdep.c | 65 ++++++++++++++++--
gdb/ppc-linux-tdep.h | 3 +
4 files changed, 103 insertions(+), 137 deletions(-)
diff --git a/gdb/gdbserver/linux-ppc-low.c b/gdb/gdbserver/linux-ppc-low.c
index ed48fa7850..91e6625121 100644
--- a/gdb/gdbserver/linux-ppc-low.c
+++ b/gdb/gdbserver/linux-ppc-low.c
@@ -486,12 +486,22 @@ ppc_fill_vrregset (struct regcache *regcache, void *buf)
{
int i, base;
char *regset = (char *) buf;
+ int vscr_offset = 0;
base = find_regno (regcache->tdesc, "vr0");
for (i = 0; i < 32; i++)
collect_register (regcache, base + i, ®set[i * 16]);
- collect_register_by_name (regcache, "vscr", ®set[32 * 16 + 12]);
+ if (__BYTE_ORDER == __BIG_ENDIAN)
+ vscr_offset = 12;
+
+ /* Zero-pad the unused bytes in the fields for vscr and vrsave in
+ case they get displayed somewhere. */
+ memset (®set[32 * 16], 0, 16);
+ collect_register_by_name (regcache, "vscr",
+ ®set[32 * 16 + vscr_offset]);
+
+ memset (®set[33 * 16], 0, 16);
collect_register_by_name (regcache, "vrsave", ®set[33 * 16]);
}
@@ -500,12 +510,17 @@ ppc_store_vrregset (struct regcache *regcache, const void *buf)
{
int i, base;
const char *regset = (const char *) buf;
+ int vscr_offset = 0;
base = find_regno (regcache->tdesc, "vr0");
for (i = 0; i < 32; i++)
supply_register (regcache, base + i, ®set[i * 16]);
- supply_register_by_name (regcache, "vscr", ®set[32 * 16 + 12]);
+ if (__BYTE_ORDER == __BIG_ENDIAN)
+ vscr_offset = 12;
+
+ supply_register_by_name (regcache, "vscr",
+ ®set[32 * 16 + vscr_offset]);
supply_register_by_name (regcache, "vrsave", ®set[33 * 16]);
}
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 554aba662e..85cd08cd8e 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -24,6 +24,7 @@
#include "gdbthread.h"
#include "gdbcore.h"
#include "regcache.h"
+#include "regset.h"
#include "target.h"
#include "linux-nat.h"
#include <sys/types.h>
@@ -160,17 +161,18 @@ struct ppc_hw_breakpoint
Even though this vrsave register is not included in the regset
typedef, it is handled by the ptrace requests.
- Note that GNU/Linux doesn't support little endian PPC hardware,
- therefore the offset at which the real value of the VSCR register
- is located will be always 12 bytes.
-
The layout is like this (where x is the actual value of the vscr reg): */
/* *INDENT-OFF* */
/*
+Big-Endian:
|.|.|.|.|.....|.|.|.|.||.|.|.|x||.|
<-------> <-------><-------><->
VR0 VR31 VSCR VRSAVE
+Little-Endian:
+ |.|.|.|.|.....|.|.|.|.||X|.|.|.||.|
+ <-------> <-------><-------><->
+ VR0 VR31 VSCR VRSAVE
*/
/* *INDENT-ON* */
@@ -435,14 +437,13 @@ fetch_vsx_register (struct regcache *regcache, int tid, int regno)
registers set mechanism, as opposed to the interface for all the
other registers, that stores/fetches each register individually. */
static void
-fetch_altivec_register (struct regcache *regcache, int tid, int regno)
+fetch_altivec_registers (struct regcache *regcache, int tid,
+ int regno)
{
int ret;
- int offset = 0;
gdb_vrregset_t regs;
struct gdbarch *gdbarch = regcache->arch ();
- struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- int vrregsize = register_size (gdbarch, tdep->ppc_vr0_regnum);
+ const struct regset *vrregset = ppc_linux_vrregset (gdbarch);
ret = ptrace (PTRACE_GETVRREGS, tid, 0, ®s);
if (ret < 0)
@@ -452,19 +453,11 @@ fetch_altivec_register (struct regcache *regcache, int tid, int regno)
have_ptrace_getvrregs = 0;
return;
}
- perror_with_name (_("Unable to fetch AltiVec register"));
+ perror_with_name (_("Unable to fetch AltiVec registers"));
}
-
- /* VSCR is fetched as a 16 bytes quantity, but it is really 4 bytes
- long on the hardware. We deal only with the lower 4 bytes of the
- vector. VRSAVE is at the end of the array in a 4 bytes slot, so
- there is no need to define an offset for it. */
- if (regno == (tdep->ppc_vrsave_regnum - 1))
- offset = vrregsize - register_size (gdbarch, tdep->ppc_vrsave_regnum);
-
- regcache_raw_supply (regcache, regno,
- regs + (regno
- - tdep->ppc_vr0_regnum) * vrregsize + offset);
+
+ vrregset->supply_regset(vrregset, regcache, regno, ®s,
+ PPC_LINUX_SIZEOF_VRREGSET);
}
/* Fetch the top 32 bits of TID's general-purpose registers and the
@@ -559,7 +552,7 @@ fetch_register (struct regcache *regcache, int tid, int regno)
register. */
if (have_ptrace_getvrregs)
{
- fetch_altivec_register (regcache, tid, regno);
+ fetch_altivec_registers (regcache, tid, regno);
return;
}
/* If we have discovered that there is no ptrace support for
@@ -647,31 +640,6 @@ supply_vsxregset (struct regcache *regcache, gdb_vsxregset_t *vsxregsetp)
}
static void
-supply_vrregset (struct regcache *regcache, gdb_vrregset_t *vrregsetp)
-{
- int i;
- struct gdbarch *gdbarch = regcache->arch ();
- struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- int num_of_vrregs = tdep->ppc_vrsave_regnum - tdep->ppc_vr0_regnum + 1;
- int vrregsize = register_size (gdbarch, tdep->ppc_vr0_regnum);
- int offset = vrregsize - register_size (gdbarch, tdep->ppc_vrsave_regnum);
-
- for (i = 0; i < num_of_vrregs; i++)
- {
- /* The last 2 registers of this set are only 32 bit long, not
- 128. However an offset is necessary only for VSCR because it
- occupies a whole vector, while VRSAVE occupies a full 4 bytes
- slot. */
- if (i == (num_of_vrregs - 2))
- regcache_raw_supply (regcache, tdep->ppc_vr0_regnum + i,
- *vrregsetp + i * vrregsize + offset);
- else
- regcache_raw_supply (regcache, tdep->ppc_vr0_regnum + i,
- *vrregsetp + i * vrregsize);
- }
-}
-
-static void
fetch_vsx_registers (struct regcache *regcache, int tid)
{
int ret;
@@ -690,25 +658,6 @@ fetch_vsx_registers (struct regcache *regcache, int tid)
supply_vsxregset (regcache, ®s);
}
-static void
-fetch_altivec_registers (struct regcache *regcache, int tid)
-{
- int ret;
- gdb_vrregset_t regs;
-
- ret = ptrace (PTRACE_GETVRREGS, tid, 0, ®s);
- if (ret < 0)
- {
- if (errno == EIO)
- {
- have_ptrace_getvrregs = 0;
- return;
- }
- perror_with_name (_("Unable to fetch AltiVec registers"));
- }
- supply_vrregset (regcache, ®s);
-}
-
/* This function actually issues the request to ptrace, telling
it to get all general-purpose registers and put them into the
specified regset.
@@ -847,7 +796,7 @@ fetch_ppc_registers (struct regcache *regcache, int tid)
fetch_register (regcache, tid, tdep->ppc_fpscr_regnum);
if (have_ptrace_getvrregs)
if (tdep->ppc_vr0_regnum != -1 && tdep->ppc_vrsave_regnum != -1)
- fetch_altivec_registers (regcache, tid);
+ fetch_altivec_registers (regcache, tid, -1);
if (have_ptrace_getsetvsxregs)
if (tdep->ppc_vsr0_upper_regnum != -1)
fetch_vsx_registers (regcache, tid);
@@ -898,16 +847,14 @@ store_vsx_register (const struct regcache *regcache, int tid, int regno)
perror_with_name (_("Unable to store VSX register"));
}
-/* Store one register. */
static void
-store_altivec_register (const struct regcache *regcache, int tid, int regno)
+store_altivec_registers (const struct regcache *regcache, int tid,
+ int regno)
{
int ret;
- int offset = 0;
gdb_vrregset_t regs;
struct gdbarch *gdbarch = regcache->arch ();
- struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- int vrregsize = register_size (gdbarch, tdep->ppc_vr0_regnum);
+ const struct regset *vrregset = ppc_linux_vrregset (gdbarch);
ret = ptrace (PTRACE_GETVRREGS, tid, 0, ®s);
if (ret < 0)
@@ -917,21 +864,15 @@ store_altivec_register (const struct regcache *regcache, int tid, int regno)
have_ptrace_getvrregs = 0;
return;
}
- perror_with_name (_("Unable to fetch AltiVec register"));
+ perror_with_name (_("Unable to fetch AltiVec registers"));
}
- /* VSCR is fetched as a 16 bytes quantity, but it is really 4 bytes
- long on the hardware. */
- if (regno == (tdep->ppc_vrsave_regnum - 1))
- offset = vrregsize - register_size (gdbarch, tdep->ppc_vrsave_regnum);
-
- regcache_raw_collect (regcache, regno,
- regs + (regno
- - tdep->ppc_vr0_regnum) * vrregsize + offset);
+ vrregset->collect_regset (vrregset, regcache, regno, ®s,
+ PPC_LINUX_SIZEOF_VRREGSET);
ret = ptrace (PTRACE_SETVRREGS, tid, 0, ®s);
if (ret < 0)
- perror_with_name (_("Unable to store AltiVec register"));
+ perror_with_name (_("Unable to store AltiVec registers"));
}
/* Assuming TID referrs to an SPE process, set the top halves of TID's
@@ -1034,7 +975,7 @@ store_register (const struct regcache *regcache, int tid, int regno)
if (altivec_register_p (gdbarch, regno))
{
- store_altivec_register (regcache, tid, regno);
+ store_altivec_registers (regcache, tid, regno);
return;
}
if (vsx_register_p (gdbarch, regno))
@@ -1111,29 +1052,6 @@ fill_vsxregset (const struct regcache *regcache, gdb_vsxregset_t *vsxregsetp)
}
static void
-fill_vrregset (const struct regcache *regcache, gdb_vrregset_t *vrregsetp)
-{
- int i;
- struct gdbarch *gdbarch = regcache->arch ();
- struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- int num_of_vrregs = tdep->ppc_vrsave_regnum - tdep->ppc_vr0_regnum + 1;
- int vrregsize = register_size (gdbarch, tdep->ppc_vr0_regnum);
- int offset = vrregsize - register_size (gdbarch, tdep->ppc_vrsave_regnum);
-
- for (i = 0; i < num_of_vrregs; i++)
- {
- /* The last 2 registers of this set are only 32 bit long, not
- 128, but only VSCR is fetched as a 16 bytes quantity. */
- if (i == (num_of_vrregs - 2))
- regcache_raw_collect (regcache, tdep->ppc_vr0_regnum + i,
- *vrregsetp + i * vrregsize + offset);
- else
- regcache_raw_collect (regcache, tdep->ppc_vr0_regnum + i,
- *vrregsetp + i * vrregsize);
- }
-}
-
-static void
store_vsx_registers (const struct regcache *regcache, int tid)
{
int ret;
@@ -1156,29 +1074,6 @@ store_vsx_registers (const struct regcache *regcache, int tid)
perror_with_name (_("Couldn't write VSX registers"));
}
-static void
-store_altivec_registers (const struct regcache *regcache, int tid)
-{
- int ret;
- gdb_vrregset_t regs;
-
- ret = ptrace (PTRACE_GETVRREGS, tid, 0, ®s);
- if (ret < 0)
- {
- if (errno == EIO)
- {
- have_ptrace_getvrregs = 0;
- return;
- }
- perror_with_name (_("Couldn't get AltiVec registers"));
- }
-
- fill_vrregset (regcache, ®s);
-
- if (ptrace (PTRACE_SETVRREGS, tid, 0, ®s) < 0)
- perror_with_name (_("Couldn't write AltiVec registers"));
-}
-
/* This function actually issues the request to ptrace, telling
it to store all general-purpose registers present in the specified
regset.
@@ -1337,7 +1232,7 @@ store_ppc_registers (const struct regcache *regcache, int tid)
}
if (have_ptrace_getvrregs)
if (tdep->ppc_vr0_regnum != -1 && tdep->ppc_vrsave_regnum != -1)
- store_altivec_registers (regcache, tid);
+ store_altivec_registers (regcache, tid, -1);
if (have_ptrace_getsetvsxregs)
if (tdep->ppc_vsr0_upper_regnum != -1)
store_vsx_registers (regcache, tid);
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 344069d752..3c8ba26f8e 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -444,6 +444,24 @@ ppc_linux_collect_gregset (const struct regset *regset,
}
}
+static void
+ppc_linux_collect_vrregset (const struct regset *regset,
+ const struct regcache *regcache,
+ int regnum, void *buf, size_t len)
+{
+ gdb_byte *vrregs = (gdb_byte *) buf;
+
+ /* Zero-pad the unused bytes in the fields for vscr and vrsave
+ in case they get displayed somewhere (e.g. in core files). */
+ if (regnum == PPC_VSCR_REGNUM || regnum == -1)
+ memset (&vrregs[32 * 16], 0, 16);
+
+ if (regnum == PPC_VRSAVE_REGNUM || regnum == -1)
+ memset (&vrregs[33 * 16], 0, 16);
+
+ regcache_collect_regset (regset, regcache, regnum, buf, len);
+}
+
/* Regset descriptions. */
static const struct ppc_reg_offsets ppc32_linux_reg_offsets =
{
@@ -513,10 +531,33 @@ static const struct regset ppc32_linux_fpregset = {
ppc_collect_fpregset
};
-static const struct regset ppc32_linux_vrregset = {
- &ppc32_linux_reg_offsets,
- ppc_supply_vrregset,
- ppc_collect_vrregset
+static const struct regcache_map_entry ppc32_le_linux_vrregmap[] =
+ {
+ { 32, PPC_VR0_REGNUM, 16 },
+ { 1, PPC_VSCR_REGNUM, 16 },
+ { 1, PPC_VRSAVE_REGNUM, 16 },
+ { 0 }
+ };
+
+static const struct regcache_map_entry ppc32_be_linux_vrregmap[] =
+ {
+ { 32, PPC_VR0_REGNUM, 16 },
+ { 1, REGCACHE_MAP_SKIP, 12},
+ { 1, PPC_VSCR_REGNUM, 4 },
+ { 1, PPC_VRSAVE_REGNUM, 16 },
+ { 0 }
+ };
+
+static const struct regset ppc32_le_linux_vrregset = {
+ ppc32_le_linux_vrregmap,
+ regcache_supply_regset,
+ ppc_linux_collect_vrregset
+};
+
+static const struct regset ppc32_be_linux_vrregset = {
+ ppc32_be_linux_vrregmap,
+ regcache_supply_regset,
+ ppc_linux_collect_vrregset
};
static const struct regset ppc32_linux_vsxregset = {
@@ -537,6 +578,15 @@ ppc_linux_fpregset (void)
return &ppc32_linux_fpregset;
}
+const struct regset *
+ppc_linux_vrregset (struct gdbarch *gdbarch)
+{
+ if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+ return &ppc32_be_linux_vrregset;
+ else
+ return &ppc32_le_linux_vrregset;
+}
+
/* Iterate over supported core file register note sections. */
static void
@@ -557,8 +607,11 @@ ppc_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
cb (".reg2", 264, &ppc32_linux_fpregset, NULL, cb_data);
if (have_altivec)
- cb (".reg-ppc-vmx", PPC_LINUX_SIZEOF_VRREGSET, &ppc32_linux_vrregset,
- "ppc Altivec", cb_data);
+ {
+ const struct regset *vrregset = ppc_linux_vrregset(gdbarch);
+ cb (".reg-ppc-vmx", PPC_LINUX_SIZEOF_VRREGSET, vrregset,
+ "ppc Altivec", cb_data);
+ }
if (have_vsx)
cb (".reg-ppc-vsx", PPC_LINUX_SIZEOF_VSXREGSET,
diff --git a/gdb/ppc-linux-tdep.h b/gdb/ppc-linux-tdep.h
index 5e7c4be16b..a8715bd418 100644
--- a/gdb/ppc-linux-tdep.h
+++ b/gdb/ppc-linux-tdep.h
@@ -28,6 +28,9 @@ struct regset;
const struct regset *ppc_linux_gregset (int);
const struct regset *ppc_linux_fpregset (void);
+/* Get the vector regset that matches the target byte order. */
+const struct regset *ppc_linux_vrregset (struct gdbarch *gdbarch);
+
/* Extra register number constants. The Linux kernel stores a
"trap" code and the original value of r3 into special "registers";
these need to be saved and restored when performing an inferior
--
2.13.6