From: Paul Burton <paul.burton@imgtec.com> To: <linux-mips@linux-mips.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk>, <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>, Paul Burton <paul.burton@imgtec.com> Subject: [PATCH 10/10] MIPS: Kconfig option to better exercise/debug hybrid FPRs Date: Thu, 11 Sep 2014 08:30:23 +0100 [thread overview] Message-ID: <1410420623-11691-11-git-send-email-paul.burton@imgtec.com> (raw) In-Reply-To: <1410420623-11691-1-git-send-email-paul.burton@imgtec.com> The hybrid FPR scheme exists to allow for compatibility between existing FP32 code and newly compiled FP64A code. Such code should hopefully be rare in the real world, and for the moment is difficult to come across. All code except that built for the FP64 ABI can correctly execute using the hybrid FPR scheme, so debugging the hybrid FPR implementation can be eased by forcing all such code to use it. This is undesirable in general due to the trap & emulate overhead of the hybrid FPR implementation, but is a very useful option to have for debugging. Signed-off-by: Paul Burton <paul.burton@imgtec.com> --- arch/mips/Kconfig.debug | 13 +++++++++++++ arch/mips/kernel/elf.c | 18 ++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug index 3a2b775..88a9f43 100644 --- a/arch/mips/Kconfig.debug +++ b/arch/mips/Kconfig.debug @@ -122,4 +122,17 @@ config SPINLOCK_TEST help Add several files to the debugfs to test spinlock speed. +config FP32XX_HYBRID_FPRS + bool "Run FP32 & FPXX code with hybrid FPRs" + depends on MIPS_O32_FP64_SUPPORT + help + The hybrid FPR scheme is normally used only when a program needs to + execute a mix of FP32 & FP64A code, since the trapping & emulation + that it entails is expensive. When enabled, this option will lead + to the kernel running programs which use the FP32 & FPXX FP ABIs + using the hybrid FPR scheme, which can be useful for debugging + purposes. + + If unsure, say N. + endmenu diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c index 34e9af5..abf8a1a 100644 --- a/arch/mips/kernel/elf.c +++ b/arch/mips/kernel/elf.c @@ -124,6 +124,24 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void mips_set_personality_fp(struct arch_elf_state *state) { + if (config_enabled(CONFIG_FP32XX_HYBRID_FPRS)) { + /* + * Use hybrid FPRs for all code which can correctly execute + * with that mode. + */ + switch (state->overall_abi) { + case MIPS_ABI_FP_DOUBLE: + case MIPS_ABI_FP_SINGLE: + case MIPS_ABI_FP_SOFT: + case MIPS_ABI_FP_XX: + case MIPS_ABI_FP_ANY: + /* FR=1, FRE=1 */ + clear_thread_flag(TIF_32BIT_FPREGS); + set_thread_flag(TIF_HYBRID_FPREGS); + return; + } + } + switch (state->overall_abi) { case MIPS_ABI_FP_DOUBLE: case MIPS_ABI_FP_SINGLE: -- 2.0.4
WARNING: multiple messages have this Message-ID (diff)
From: Paul Burton <paul.burton@imgtec.com> To: linux-mips@linux-mips.org Cc: Alexander Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Burton <paul.burton@imgtec.com> Subject: [PATCH 10/10] MIPS: Kconfig option to better exercise/debug hybrid FPRs Date: Thu, 11 Sep 2014 08:30:23 +0100 [thread overview] Message-ID: <1410420623-11691-11-git-send-email-paul.burton@imgtec.com> (raw) Message-ID: <20140911073023.v7nNj9jmAoXSjChD3_cpCYgMrqUp24N5ckYC8IeKoTk@z> (raw) In-Reply-To: <1410420623-11691-1-git-send-email-paul.burton@imgtec.com> The hybrid FPR scheme exists to allow for compatibility between existing FP32 code and newly compiled FP64A code. Such code should hopefully be rare in the real world, and for the moment is difficult to come across. All code except that built for the FP64 ABI can correctly execute using the hybrid FPR scheme, so debugging the hybrid FPR implementation can be eased by forcing all such code to use it. This is undesirable in general due to the trap & emulate overhead of the hybrid FPR implementation, but is a very useful option to have for debugging. Signed-off-by: Paul Burton <paul.burton@imgtec.com> --- arch/mips/Kconfig.debug | 13 +++++++++++++ arch/mips/kernel/elf.c | 18 ++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug index 3a2b775..88a9f43 100644 --- a/arch/mips/Kconfig.debug +++ b/arch/mips/Kconfig.debug @@ -122,4 +122,17 @@ config SPINLOCK_TEST help Add several files to the debugfs to test spinlock speed. +config FP32XX_HYBRID_FPRS + bool "Run FP32 & FPXX code with hybrid FPRs" + depends on MIPS_O32_FP64_SUPPORT + help + The hybrid FPR scheme is normally used only when a program needs to + execute a mix of FP32 & FP64A code, since the trapping & emulation + that it entails is expensive. When enabled, this option will lead + to the kernel running programs which use the FP32 & FPXX FP ABIs + using the hybrid FPR scheme, which can be useful for debugging + purposes. + + If unsure, say N. + endmenu diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c index 34e9af5..abf8a1a 100644 --- a/arch/mips/kernel/elf.c +++ b/arch/mips/kernel/elf.c @@ -124,6 +124,24 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void mips_set_personality_fp(struct arch_elf_state *state) { + if (config_enabled(CONFIG_FP32XX_HYBRID_FPRS)) { + /* + * Use hybrid FPRs for all code which can correctly execute + * with that mode. + */ + switch (state->overall_abi) { + case MIPS_ABI_FP_DOUBLE: + case MIPS_ABI_FP_SINGLE: + case MIPS_ABI_FP_SOFT: + case MIPS_ABI_FP_XX: + case MIPS_ABI_FP_ANY: + /* FR=1, FRE=1 */ + clear_thread_flag(TIF_32BIT_FPREGS); + set_thread_flag(TIF_HYBRID_FPREGS); + return; + } + } + switch (state->overall_abi) { case MIPS_ABI_FP_DOUBLE: case MIPS_ABI_FP_SINGLE: -- 2.0.4
next prev parent reply other threads:[~2014-09-11 8:47 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-09-11 7:30 [PATCH 00/10] MIPS O32 new FP ABI support Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 01/10] binfmt_elf: hoist ELF program header loading to a function Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 02/10] binfmt_elf: load interpreter program headers earlier Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-11-13 12:20 ` Thierry Reding 2014-11-13 17:29 ` Ralf Baechle 2014-09-11 7:30 ` [PATCH 03/10] binfmt_elf: allow arch code to examine PT_LOPROC ... PT_HIPROC headers Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-11-12 13:41 ` Thierry Reding 2014-11-13 0:16 ` Ralf Baechle 2014-11-13 12:25 ` Thierry Reding 2014-09-11 7:30 ` [PATCH 04/10] MIPS: define bits introduced for hybrid FPRs Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 05/10] MIPS: detect presence of the FRE & UFR bits Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 06/10] MIPS: ensure Config5.UFE is clear on boot Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 07/10] MIPS: support for hybrid FPRs Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-12-23 23:21 ` Aaro Koskinen 2014-12-23 23:31 ` James Hogan 2014-12-23 23:31 ` James Hogan 2014-12-23 23:51 ` Aaro Koskinen 2014-09-11 7:30 ` [PATCH 08/10] MIPS: ELF: add definition for the .MIPS.abiflags section Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` [PATCH 09/10] MIPS: ELF: set FP mode according to .MIPS.abiflags Paul Burton 2014-09-11 7:30 ` Paul Burton 2014-09-11 7:30 ` Paul Burton [this message] 2014-09-11 7:30 ` [PATCH 10/10] MIPS: Kconfig option to better exercise/debug hybrid FPRs Paul Burton
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