From 232bfb8644f0a083969d8359a37bc23764642611 Mon Sep 17 00:00:00 2001 From: Edjunior Barbosa Machado Date: Fri, 26 Oct 2018 09:37:54 -0300 Subject: [PowerPC] Add support for EBB and PMU registers This patch adds support for registers of the Event Based Branching and Performance Monitoring Units for the powerpc linux native and core file targets, and for the powerpc linux server stub. All three EBB registers are accessible. Only a subset of the PMU registers can be accessed through ptrace. Because of this, the PMU registers are enumerated individually in gdbarch_tdep, as opposed to having a single "have_pmu" flag. This is intended to make it easier to add additional PMU registers in the future, since checking a "have_pmu" flag elsewhere in the code would no longer be correct. The tdesc feature is named org.gnu.gdb.power.linux.pmu because of this. It's unclear if it makes sense to save and restore these registers across function calls, since some of them can be modified asynchronously. They are also not tracked in record-replay mode. The kernel can return ENODATA when ptrace is used to get the EBB registers, unless a linux performance event that uses EBB is open in the inferior. For this reason, the "fill" functions in the server stub for the ebb register sets is not implemented. Since gdbserver writes all registers in one go before resuming the inferior, this error would not be detected at the time the user tries to write to one of the registers on the client side, and gdbserver would print out warnings every time it resumes the inferior when no ebb performance event is opened, so there is currently no straightforward way to handle this case. This means the ebb registers in the client-side regcache can become dirty when the user tries to write to them, until the inferior is resumed and stopped again. A related issue is that 'G' packets used to write to unrelated registers will include bad data for the EBB registers if they are unavailable, since no register status information is included in the 'G' packet. This data won't be written to the inferior by the gdbserver stub because the "fill" functions are not implemented, and currently the gdbserver stub doesn't change the status of the registers in its own regcache in response to 'G' packets. Another limitation for the ebb registers is that traceframes don't record if registers are available or not, so if these registers are collected when a tracepoint is hit and the inferior has no ebb event opened, the user will see zero values for all of them, instead of the usual . Because these registers are often unavailable, trying to store them with target_store_registers with -1 for the regno argument (all registers) would almost always fail, so they are ignored in this case. gdb/ChangeLog: 2018-10-26 Edjunior Barbosa Machado Pedro Franco de Carvalho * arch/ppc-linux-common.h (PPC_LINUX_SIZEOF_EBBREGSET) (PPC_LINUX_SIZEOF_PMUREGSET): Declare. * nat/ppc-linux.h (PPC_FEATURE2_EBB, NT_PPC_EBB, NT_PPC_PMU): Define if not already defined. * features/rs6000/power-ebb.xml: New file. * features/rs6000/power-linux-pmu.xml: New file. * features/rs6000/powerpc-isa207-vsx32l.xml: Include ebb and pmu features. * features/rs6000/powerpc-isa207-vsx64l.xml: Likewise. * features/rs6000/powerpc-isa207-vsx32l.c: Re-generate. * features/rs6000/powerpc-isa207-vsx64l.c: Re-generate. * regformats/rs6000/powerpc-isa207-vsx32l.dat: Re-generate. * regformats/rs6000/powerpc-isa207-vsx64l.dat: Re-generate. * ppc-linux-nat.c (fetch_register, fetch_ppc_registers): Call fetch_regset with ebb and pmu regsets. (store_register, store_ppc_registers): Call store_regset with ebb and pmu regsets. (ppc_linux_nat_target::read_description): Set isa207 field in the features struct if ebb and pmu are avaiable. * ppc-linux-tdep.c (ppc32_regmap_ebb, ppc32_regmap_pmu) (ppc32_linux_ebbregset, ppc32_linux_pmuregset): New globals. (ppc_linux_iterate_over_regset_sections): Call back with the ebb and pmu regsets. (ppc_linux_core_read_description): Check if the pmu section is present and set isa207 in the features struct. * ppc-linux-tdep.h (ppc32_linux_ebbregset) (ppc32_linux_pmuregset): Declare. * ppc-tdep.h (struct gdbarch_tdep) : New field. : New fields. : New field. (enum): : New enum values. : New enum values. : New enum values. (PPC_IS_EBB_REGNUM, PPC_IS_PMU_REGNUM): Define. * rs6000-tdep.c (rs6000_gdbarch_init): Look for and validate the ebb and pmu features. gdb/gdbserver/ChangeLog: 2018-10-26 Pedro Franco de Carvalho * configure.srv (powerpc*-*-linux*): Add rs6000/power-ebb.xml and rs6000/power-linux-pmu.xml to srv_xmlfiles. * linux-ppc-low.c (ppc_store_ebbregset, ppc_fill_pmuregset) (ppc_store_pmuregset): New functions. (ppc_regsets): Add entries for ebb and pmu regsets. (ppc_arch_setup): Set isa207 in features struct if the ebb and pmu regsets are available. Set sizes for these regsets. gdb/doc/ChangeLog: 2018-10-26 Pedro Franco de Carvalho * gdb.texinfo (PowerPC Features): Describe new features "org.gnu.gdb.power.ebb" and "org.gnu.gdb.power.linux.pmu". --- gdb/arch/ppc-linux-common.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'gdb/arch') diff --git a/gdb/arch/ppc-linux-common.h b/gdb/arch/ppc-linux-common.h index f0e4a42..50e9e06 100644 --- a/gdb/arch/ppc-linux-common.h +++ b/gdb/arch/ppc-linux-common.h @@ -33,6 +33,8 @@ struct target_desc; #define PPC_LINUX_SIZEOF_PPRREGSET 8 #define PPC_LINUX_SIZEOF_DSCRREGSET 8 #define PPC_LINUX_SIZEOF_TARREGSET 8 +#define PPC_LINUX_SIZEOF_EBBREGSET (3*8) +#define PPC_LINUX_SIZEOF_PMUREGSET (5*8) /* Check if the hwcap auxv entry indicates that isa205 is supported. */ bool ppc_linux_has_isa205 (CORE_ADDR hwcap); -- cgit v1.1