[PATCH v2 03/11] s390: Initial support to generate .sframe from CFI directives in assembler
Indu Bhagat
indu.bhagat@oracle.com
Mon Jun 2 20:35:06 GMT 2025
On 5/27/25 4:07 AM, Jens Remus wrote:
> This introduces initial support to generate .sframe from CFI directives
> in assembler on s390 64-bit (s390x). Due to SFrame V2 format
> limitations it has the following limitations, some of them getting
> addressed by subsequent patches, which cause generation of SFrame FDE
> to be skipped:
>
> - SFrame FP/RA tracking only supports register contents being saved on
> the stack (i.e. .cfi_offset). It does not support FP/RA register
> contents being saved in other registers (i.e. .cfi_register). GCC on
> s390x can be observed to save the FP/RA register contents in floating-
> point registers, but only in leaf functions.
>
Nit: it may be worth adding a statement here, something that says that a
subsequent commit addresses this issue. I see you mention that in the
cover letter, but mentioning here in the git commit log will help
establish the connection for posterity.
This issue is detailed further and resolved in a later commit [s390:
Represent FP/RA saved in register in SFrame].
> - SFrame FP/RA tracking cannot represent FP without RA saved. This is
> because the format assumes SFrame FDE offset2 to be the RA offset, if
> there are two offsets, and offset3 to be the FP offset, if there are
> three offsets. There is no mean to distinguish whether offset2 is the
> RA or FP offset, if there are only two offsets.
>
Similarly:
This issue is detailed further and resolved in a later commit [s390:
Represent FP without RA saved in SFrame].
Some nits/comments below.
> - SFrame assumes a dedicated FP register number. The s390x ELF ABI [1]
> does only designate register 11 as preferred FP register number. In
> general GCC and Clang on s390x use register 11 as frame pointer.
> GCC on s390x can be observed to use register 14 as frame pointer in
> the stack clash protector in the function prologue.
> glibc on s390x contains hand-written assembler code that uses
> register 12 as frame pointer.
>
> This s390x support is largely based on the AArch64 support from commit
> b52c4ee46657 ("gas: generate .sframe from CFI directives").
>
> The SFrame ABI/arch identifier SFRAME_ABI_S390X_ENDIAN_BIG is introduced
> for s390x and added to the SFrame format specification.
>
> The s390x ELF ABI [1] specifies the following C calling conventions for
> s390x architecture:
> - Register 15 is the stack pointer (SP).
> - Register 14 contains the return address (RA) at function entry.
> - There is no dedicated frame pointer register. Register 11 is the
> preferred frame pointer (FP). [2] GCC and Clang in general use
> register 11 as frame pointer.
> - The CFA is defined as SP at call site +160. [3] The SP at call site
> can therefore be derived from the CFA using a SP value offset from CFA
> of -160.
>
> The s390x ELF ABI [1] does not assign any standard save slot to each
> register in the register save area of a stack frame. Neither the
> return address (RA, r14) nor preferred frame pointer (FP, r11)
> necessarily need to be saved. Therefore SFrame RA and FP tracking is
> used.
>
> Support for SFrame on s390 is only enabled for the 64-bit s390x ELF ABI
> (z/Architecture with 64-bit addressing mode). It is disabled for the
> 32-bit s390 ELF ABI (ESA/390 or z/Architecture with 32-bit addressing
> mode).
>
> s390x-specific SFrame assembler and linker tests are added, including
> error tests for use of a non-preferred frame pointer (FP) register and
> specification of a non-default return address (RA) register.
>
> [1]: s390x ELF ABI, https://github.com/IBM/s390x-abi/releases
> [2]: s390x ELF ABI, commit f00421825979 ("Add information about the frame
> pointer register"),
> https://github.com/IBM/s390x-abi/commit/f00421825979
> [3]: s390x ELF ABI, commit 4e38ad9c8a88 ("Document the CFA"),
> https://github.com/IBM/s390x-abi/commit/4e38ad9c8a88
>
> include/
> * sframe.h: Add reference to s390x architecture in comments.
> (SFRAME_ABI_S390X_ENDIAN_BIG): Define SFrame ABI/arch identifier
> for s390x.
> (SFRAME_S390X_SP_VAL_OFFSET): Define s390x-specific SP value
> offset from CFA.
>
> libsframe/
> * sframe.c (need_swapping): Add SFRAME_ABI_S390X_ENDIAN_BIG.
> * doc/sframe-spec.texi (SFRAME_ABI_S390X_ENDIAN_BIG, s390x,
> SFRAME_S390X_SP_VAL_OFFSET): Document SFrame ABI/arch identifier
> for s390x, add references to s390x architecture, and document
> s390x-specifics, such as the SP value offset from CFA of -160.
>
> gas/
> * config/tc-s390.h: s390x support to generate .sframe from CFI
> directives in assembler.
> (support_sframe_p): Define.
> (SFRAME_CFA_SP_REG, SFRAME_CFA_FP_REG, SFRAME_CFA_RA_REG):
> Define.
> (sframe_ra_tracking_p): Define.
> (sframe_cfa_ra_offset): Define.
> (sframe_get_abi_arch): Define.
> * config/tc-s390.c: s390x support to generate .sframe from CFI
> directives in assembler.
> (s390_sframe_cfa_sp_reg, s390_sframe_cfa_fp_reg,
> s390_sframe_cfa_ra_reg): New. Initialize to DWARF register
> numbers of stack pointer (SP, r15), preferred frame pointer
> (FP, r11), and return address (RA, r14) registers.
> (s390_support_sframe_p): New function. Return true if s390x.
> (s390_sframe_ra_tracking_p): New function. Return true.
> (s390_sframe_cfa_ra_offset): New function. Return
> SFRAME_CFA_FIXED_RA_INVALID.
> (s390_sframe_get_abi_arch): New function. Return
> SFRAME_ABI_S390X_ENDIAN_BIG if s390x, otherwise zero.
> * gen-sframe.c: Add reference to s390x architecture in comments.
> (sframe_xlate_do_val_offset): Add support for s390x-specific
> SFRAME_S390X_SP_VAL_OFFSET.
> * NEWS: Add news entry.
>
> gas/testsuite/
> * gas/cfi-sframe/cfi-sframe.exp: Enable common SFrame tests for
> s390x. Add s390x-specific SFrame (error) tests.
> * gas/cfi-sframe/cfi-sframe-s390x-1.d: New s390x-specific SFrame
> test.
> * gas/cfi-sframe/cfi-sframe-s390x-1.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-2.d: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-2.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-err-1.d: New s390x-specific
> SFrame error test that uses a non-default frame-pointer register
> as CFA base register.
> * gas/cfi-sframe/cfi-sframe-s390x-err-1.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-err-2.d: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-err-2.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-err-3.d: New s390x-specific
> SFrame error test that uses a non-default return address
> register.
> * gas/cfi-sframe/cfi-sframe-s390x-err-3.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.d: New s390x-
> specific SFrame test that saves RA and FP individually on the
> stack.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.d: New
> s390x-specific SFrame error test that saves FP and RA
> individually, to trigger FP without RA saved.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.s: Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.d: New
> s390x-specific SFrame error test that saves FP and RA
> individually in registers.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.s:
> Likewise.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.d: New
> s390x-specific SFrame error test that saves RA and FP
> individually in registers.
> * gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.s:
> Likewise.
>
> ld/testsuite/
> * ld-s390/s390.exp: Add simple SFrame test.
> * ld-s390/sframe-simple-1.d: New simple SFrame test.
> * ld-s390/sframe-bar.s: Likewise.
> * ld-s390/sframe-foo.s: Likewise.
>
> Signed-off-by: Jens Remus <jremus@linux.ibm.com>
> ---
>
> Notes (jremus):
> Changes in V2:
> - Reword commit message (s390 to s390x). (Indu)
> - Fix typo in GNU ChangeLog. (Indu)
> - Reword comments on s390_sframe_cfa_{sp|fp|ra}_reg. (Indu)
> - Fix typo in comment on s390_sframe_get_abi_arch. (Indu)
> - Rename s390x-specific macros from *_S390_* to *_S390X_*. (Indu)
> - Use "s390x" instead of "S390" in comments and SFrame spec. (Indu)
> - Rename CFI SFrame test file names from s390 to s390x. (Indu)
> - Reword test names. Use s390x-default stack frame size of 160 bytes.
> - Adjust tests to commit bd9dc0a281a4 ("gas: sframe: reword diagnostic
> to address ambiguity")
> - Use const for s390_sframe_cfa_{sp|fp|ra}_reg. (Jan)
> - Mention SFRAME_S390X_SP_VAL_OFFSET in appendix "Generating Stack
> Traces using SFrame".
> - Reword SFrame specs for s390x. Mention when FP/RA may be unsaved.
> (Indu)
> - Reword NEWS ("s390 64-bit (s390x)").
>
> gas/NEWS | 3 +
> gas/config/tc-s390.c | 55 ++++++++++++++++++
> gas/config/tc-s390.h | 31 ++++++++++
> gas/gen-sframe.c | 8 ++-
> .../gas/cfi-sframe/cfi-sframe-s390x-1.d | 23 ++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-1.s | 37 ++++++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-2.d | 23 ++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-2.s | 37 ++++++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-1.d | 15 +++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-1.s | 37 ++++++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-2.d | 15 +++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-2.s | 37 ++++++++++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-3.d | 15 +++++
> .../gas/cfi-sframe/cfi-sframe-s390x-err-3.s | 5 ++
> .../cfi-sframe-s390x-fpra-offset-1.d | 22 ++++++++
> .../cfi-sframe-s390x-fpra-offset-1.s | 15 +++++
> .../cfi-sframe-s390x-fpra-offset-err-1.d | 15 +++++
> .../cfi-sframe-s390x-fpra-offset-err-1.s | 15 +++++
> .../cfi-sframe-s390x-fpra-register-err-1.d | 15 +++++
> .../cfi-sframe-s390x-fpra-register-err-1.s | 15 +++++
> .../cfi-sframe-s390x-fpra-register-err-2.d | 15 +++++
> .../cfi-sframe-s390x-fpra-register-err-2.s | 15 +++++
> gas/testsuite/gas/cfi-sframe/cfi-sframe.exp | 16 +++++-
> include/sframe.h | 11 +++-
> ld/testsuite/ld-s390/s390.exp | 4 ++
> ld/testsuite/ld-s390/sframe-bar.s | 21 +++++++
> ld/testsuite/ld-s390/sframe-foo.s | 9 +++
> ld/testsuite/ld-s390/sframe-simple-1.d | 30 ++++++++++
> libsframe/doc/sframe-spec.texi | 56 ++++++++++++++++++-
> libsframe/sframe.c | 1 +
> 30 files changed, 607 insertions(+), 9 deletions(-)
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.s
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.d
> create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.s
> create mode 100644 ld/testsuite/ld-s390/sframe-bar.s
> create mode 100644 ld/testsuite/ld-s390/sframe-foo.s
> create mode 100644 ld/testsuite/ld-s390/sframe-simple-1.d
>
> diff --git a/gas/NEWS b/gas/NEWS
> index 6febdc263007..c3bc4cfd16b2 100644
> --- a/gas/NEWS
> +++ b/gas/NEWS
> @@ -1,5 +1,8 @@
> -*- text -*-
>
> +* Add initial support to generate SFrame stack trace information (.sframe)
> + from CFI directives on s390 64-bit (s390x).
> +
> * Support for x86 AVX10.2 256 bit rounding has been dropped, as all the
> hardware would directly support 512 bit vecotr width.
>
> diff --git a/gas/config/tc-s390.c b/gas/config/tc-s390.c
> index b84613479725..cf863f7a538f 100644
> --- a/gas/config/tc-s390.c
> +++ b/gas/config/tc-s390.c
> @@ -24,6 +24,8 @@
> #include "subsegs.h"
> #include "dwarf2dbg.h"
> #include "dw2gencfi.h"
> +#include "sframe.h"
> +#include "gen-sframe.h"
>
> #include "opcode/s390.h"
> #include "elf/s390.h"
> @@ -97,6 +99,17 @@ const char FLT_CHARS[] = "dD";
> /* The dwarf2 data alignment, adjusted for 32 or 64 bit. */
> int s390_cie_data_alignment;
>
> +/* Register numbers used for SFrame stack trace info. */
> +
> +/* Designated stack pointer DWARF register number according to s390x ELF ABI. */
> +const unsigned int s390_sframe_cfa_sp_reg = 15;
> +
> +/* Preferred frame pointer DWARF register number according to s390x ELF ABI. */
> +const unsigned int s390_sframe_cfa_fp_reg = 11;
> +
> +/* Designated return-address DWARF register number according to s390x ELF ABI. */
Nit: "return address" ? (without the -)
> +const unsigned int s390_sframe_cfa_ra_reg = DWARF2_DEFAULT_RETURN_COLUMN;
> +
> /* The target specific pseudo-ops which we support. */
>
> /* Define the prototypes for the pseudo-ops */
> @@ -2867,6 +2880,48 @@ tc_s390_regname_to_dw2regnum (char *regname)
> return regnum;
> }
>
> +/* Whether SFrame stack trace info is supported. */
> +
> +bool
> +s390_support_sframe_p (void)
> +{
> + /* At this time, SFrame is supported for s390x (64-bit) only. */
> + return (s390_arch_size == 64);
> +}
> +
> +/* Specify if RA tracking is needed. */
> +
> +bool
> +s390_sframe_ra_tracking_p (void)
> +{
> + return true;
> +}
> +
> +/* Specify the fixed offset to recover RA from CFA.
> + (useful only when RA tracking is not needed). */
> +
> +offsetT
> +s390_sframe_cfa_ra_offset (void)
> +{
> + return (offsetT) SFRAME_CFA_FIXED_RA_INVALID;
> +}
> +
> +/* Get the abi/arch identifier for SFrame. */
> +
> +unsigned char
> +s390_sframe_get_abi_arch (void)
> +{
> + unsigned char sframe_abi_arch = 0;
> +
> + if (s390_support_sframe_p ())
> + {
> + gas_assert (target_big_endian);
> + sframe_abi_arch = SFRAME_ABI_S390X_ENDIAN_BIG;
> + }
> +
> + return sframe_abi_arch;
> +}
> +
> void
> s390_elf_final_processing (void)
> {
> diff --git a/gas/config/tc-s390.h b/gas/config/tc-s390.h
> index 9206c029a1c1..c92769e507b3 100644
> --- a/gas/config/tc-s390.h
> +++ b/gas/config/tc-s390.h
> @@ -98,3 +98,34 @@ extern int s390_cie_data_alignment;
> extern void s390_elf_final_processing (void);
>
> #define elf_tc_final_processing s390_elf_final_processing
> +
> +/* SFrame. */
> +
> +/* Whether SFrame stack trace info is supported. */
> +extern bool s390_support_sframe_p (void);
> +#define support_sframe_p s390_support_sframe_p
> +
> +/* The stack pointer DWARF register number for SFrame CFA tracking. */
> +extern const unsigned int s390_sframe_cfa_sp_reg;
> +#define SFRAME_CFA_SP_REG s390_sframe_cfa_sp_reg
> +
> +/* The frame pointer DWARF register number for SFrame CFA and FP tracking. */
> +extern const unsigned int s390_sframe_cfa_fp_reg;
> +#define SFRAME_CFA_FP_REG s390_sframe_cfa_fp_reg
> +
> +/* The return address DWARF register number for SFrame RA tracking. */
> +extern const unsigned int s390_sframe_cfa_ra_reg;
> +#define SFRAME_CFA_RA_REG s390_sframe_cfa_ra_reg
> +
> +/* Whether SFrame return address tracking is needed. */
> +extern bool s390_sframe_ra_tracking_p (void);
> +#define sframe_ra_tracking_p s390_sframe_ra_tracking_p
> +
> +/* The fixed offset from CFA for SFrame to recover the return address.
> + (useful only when SFrame RA tracking is not needed). */
> +extern offsetT s390_sframe_cfa_ra_offset (void);
> +#define sframe_cfa_ra_offset s390_sframe_cfa_ra_offset
> +
> +/* The abi/arch identifier for SFrame. */
> +unsigned char s390_sframe_get_abi_arch (void);
> +#define sframe_get_abi_arch s390_sframe_get_abi_arch
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index 2d1c1961fd7e..89a61df4449e 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -707,7 +707,7 @@ output_sframe_internal (void)
> }
> out_one (fixed_ra_offset);
>
> - /* None of the AMD64, or AARCH64 ABIs need the auxiliary header.
> + /* None of the AMD64, AARCH64, or s390x ABIs need the auxiliary header.
> When the need does arise to use this field, the appropriate backend
> must provide this information. */
> out_one (0); /* Auxiliary SFrame header length. */
> @@ -1110,7 +1110,11 @@ sframe_xlate_do_val_offset (const struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_U
> if (cfi_insn->u.ri.reg == SFRAME_CFA_FP_REG
> || (sframe_ra_tracking_p () && cfi_insn->u.ri.reg == SFRAME_CFA_RA_REG)
> /* Ignore SP reg, if offset matches assumed default rule. */
> - || (cfi_insn->u.ri.reg == SFRAME_CFA_SP_REG && cfi_insn->u.ri.offset != 0))
> + || (cfi_insn->u.ri.reg == SFRAME_CFA_SP_REG
> + && ((sframe_get_abi_arch () != SFRAME_ABI_S390X_ENDIAN_BIG
> + && cfi_insn->u.ri.offset != 0)
> + || (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
> + && cfi_insn->u.ri.offset != SFRAME_S390X_SP_VAL_OFFSET))))
> {
> as_warn (_("no SFrame FDE emitted; %s with %s reg %u"),
> cfi_esc_p ? ".cfi_escape DW_CFA_val_offset" : ".cfi_val_offset",
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.d
> new file mode 100644
> index 000000000000..df7513c49100
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.d
> @@ -0,0 +1,23 @@
> +#name: SFrame generation on s390x - .cfi_offset and .cfi_def_cfa_{offset,register}
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 1
> + Num FREs: 6
> +
> + Function Index :
> +
> + func idx \[0\]: pc = 0x0, size = 40 bytes
> + STARTPC +CFA +FP +RA +
> + 0+0000 +sp\+160 +u +u +
> + 0+0006 +sp\+160 +c\-72 +c\-48 +
> + 0+000c +sp\+320 +c\-72 +c\-48 +
> + 0+0010 +fp\+320 +c\-72 +c\-48 +
> + 0+001c +sp\+160 +u +u +
> + 0+001e +fp\+320 +c\-72 +c\-48 +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.s
> new file mode 100644
> index 000000000000..e5c69b9813c4
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-1.s
> @@ -0,0 +1,37 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stmg %r6,%r15,48(%r15)
> + .cfi_offset 6, -112
> + .cfi_offset 7, -104
> + .cfi_offset 8, -96
> + .cfi_offset 9, -88
> + .cfi_offset 10, -80
> + .cfi_offset 11, -72
> + .cfi_offset 12, -64
> + .cfi_offset 13, -56
> + .cfi_offset 14, -48
> + .cfi_offset 15, -40
> + lay %r15,-160(%r15)
> + .cfi_def_cfa_offset 320
> + lgr %r11,%r15
> + .cfi_def_cfa_register 11
> + lay %r15,-128(%r15)
> +.Lreturn:
> + lmg %r6,%r15,160+48(%r11)
> + .cfi_remember_state
> + .cfi_restore 15
> + .cfi_restore 14
> + .cfi_restore 13
> + .cfi_restore 12
> + .cfi_restore 11
> + .cfi_restore 10
> + .cfi_restore 9
> + .cfi_restore 8
> + .cfi_restore 7
> + .cfi_restore 6
> + .cfi_def_cfa 15, 160
> + br %r14
> + .cfi_restore_state
> + lay %r15,-128(%r15)
Nit: space separator between lay and %r15, instead of tab in the rest of
this file. This repeats as a pattern in the rest of the tests too.
> + j .Lreturn
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.d
> new file mode 100644
> index 000000000000..78c77e780986
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.d
> @@ -0,0 +1,23 @@
> +#name: SFrame generation on s390x - .cfi_rel_offset and .cfi_def_cfa_{offset,register}
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 1
> + Num FREs: 6
> +
> + Function Index :
> +
> + func idx \[0\]: pc = 0x0, size = 40 bytes
> + STARTPC +CFA +FP +RA +
> + 0+0000 +sp\+160 +u +u +
> + 0+0006 +sp\+160 +c\-72 +c\-48 +
> + 0+000c +sp\+320 +c\-72 +c\-48 +
> + 0+0010 +fp\+320 +c\-72 +c\-48 +
> + 0+001c +sp\+160 +u +u +
> + 0+001e +fp\+320 +c\-72 +c\-48 +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.s
> new file mode 100644
> index 000000000000..dc19c628e391
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-2.s
> @@ -0,0 +1,37 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stmg %r6,%r15,48(%r15)
> + .cfi_rel_offset 6, 48
> + .cfi_rel_offset 7, 56
> + .cfi_rel_offset 8, 64
> + .cfi_rel_offset 9, 72
> + .cfi_rel_offset 10, 80
> + .cfi_rel_offset 11, 88
> + .cfi_rel_offset 12, 96
> + .cfi_rel_offset 13, 104
> + .cfi_rel_offset 14, 112
> + .cfi_rel_offset 15, 120
> + lay %r15,-160(%r15)
> + .cfi_def_cfa_offset 320
> + lgr %r11,%r15
> + .cfi_def_cfa_register 11
> + lay %r15,-128(%r15)
> +.Lreturn:
> + lmg %r6,%r15,160+48(%r11)
> + .cfi_remember_state
> + .cfi_restore 15
> + .cfi_restore 14
> + .cfi_restore 13
> + .cfi_restore 12
> + .cfi_restore 11
> + .cfi_restore 10
> + .cfi_restore 9
> + .cfi_restore 8
> + .cfi_restore 7
> + .cfi_restore 6
> + .cfi_def_cfa 15, 160
> + br %r14
> + .cfi_restore_state
> + lay %r15,-128(%r15)
> + j .Lreturn
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.d
> new file mode 100644
> index 000000000000..00361d25a6ca
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - .cfi_def_cfa_register with non-SP/FP register
> +#as: --gsframe
> +#warning: non-SP/FP register 10 in \.cfi_def_cfa_register
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.s
> new file mode 100644
> index 000000000000..acdb198a33e8
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-1.s
> @@ -0,0 +1,37 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stmg %r6,%r15,48(%r15)
> + .cfi_offset 6, -112
> + .cfi_offset 7, -104
> + .cfi_offset 8, -96
> + .cfi_offset 9, -88
> + .cfi_offset 10, -80
> + .cfi_offset 11, -72
> + .cfi_offset 12, -64
> + .cfi_offset 13, -56
> + .cfi_offset 14, -48
> + .cfi_offset 15, -40
> + lay %r15,-160(%r15)
> + .cfi_def_cfa_offset 320
> + lgr %r10,%r15
> + .cfi_def_cfa_register 10 # non-default frame-pointer register
> + lay %r15,-128(%r15)
> +.Lreturn:
> + lmg %r6,%r15,160+48(%r10)
> + .cfi_remember_state
> + .cfi_restore 15
> + .cfi_restore 14
> + .cfi_restore 13
> + .cfi_restore 12
> + .cfi_restore 11
> + .cfi_restore 10
> + .cfi_restore 9
> + .cfi_restore 8
> + .cfi_restore 7
> + .cfi_restore 6
> + .cfi_def_cfa 15, 160
> + br %r14
> + .cfi_restore_state
> + lay %r15,-128(%r15)
> + j .Lreturn
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.d
> new file mode 100644
> index 000000000000..c2f8fca8ec9e
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - .cfi_def_cfa with non-SP/FP register
> +#as: --gsframe
> +#warning: non-SP/FP register 10 in \.cfi_def_cfa
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.s
> new file mode 100644
> index 000000000000..e4742086d10d
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-2.s
> @@ -0,0 +1,37 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stmg %r6,%r15,48(%r15)
> + .cfi_offset 6, -112
> + .cfi_offset 7, -104
> + .cfi_offset 8, -96
> + .cfi_offset 9, -88
> + .cfi_offset 10, -80
> + .cfi_offset 11, -72
> + .cfi_offset 12, -64
> + .cfi_offset 13, -56
> + .cfi_offset 14, -48
> + .cfi_offset 15, -40
> + lay %r15,-160(%r15)
> + .cfi_def_cfa_offset 320
> + lgr %r10,%r15
> + .cfi_def_cfa 10, 320 # non-default frame-pointer register
> + lay %r15,-128(%r15)
> +.Lreturn:
> + lmg %r6,%r15,160+48(%r10)
> + .cfi_remember_state
> + .cfi_restore 15
> + .cfi_restore 14
> + .cfi_restore 13
> + .cfi_restore 12
> + .cfi_restore 11
> + .cfi_restore 10
> + .cfi_restore 9
> + .cfi_restore 8
> + .cfi_restore 7
> + .cfi_restore 6
> + .cfi_def_cfa 15, 160
> + br %r14
> + .cfi_restore_state
> + lay %r15,-128(%r15)
> + j .Lreturn
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.d
> new file mode 100644
> index 000000000000..db025ce23f16
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - non-default RA register
> +#as: --gsframe
> +#warning: non-default RA register 7
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.s
> new file mode 100644
> index 000000000000..40755883c827
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-err-3.s
> @@ -0,0 +1,5 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + .cfi_return_column 7 # non-default return-address register
> + br %r7
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.d
> new file mode 100644
> index 000000000000..4ab6c5770d07
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.d
> @@ -0,0 +1,22 @@
> +#name: SFrame generation on s390x - RA and then FP saved on stack
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 1
> + Num FREs: 5
> +
> + Function Index :
> +
> + func idx \[0\]: pc = 0x0, size = 34 bytes
> + STARTPC +CFA +FP +RA +
> + 0+0000 +sp\+160 +u +u +
> + 0+0006 +sp\+160 +u +c\-48 +
> + 0+000c +sp\+160 +c\-72 +c\-48 +
> + 0+001a +sp\+160 +u +c\-48 +
> + 0+0020 +sp\+160 +u +u +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.s
> new file mode 100644
> index 000000000000..3d9c8cbdb774
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-1.s
> @@ -0,0 +1,15 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stg %r14,112(%r15)
> + .cfi_rel_offset 14, 112
> + stg %r11,88(%r15)
> + .cfi_rel_offset 11, 88
> + la %r11,0
> + la %r14,0
> +.Lreturn:
> + lg %r11,88(%r15)
> + .cfi_restore 11
> + lg %r14,112(%r15)
> + .cfi_restore 14
> + br %r14
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.d
> new file mode 100644
> index 000000000000..cb88417b009a
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - FP without RA saved on stack
> +#as: --gsframe
> +#warning: FP without RA on stack
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.s
> new file mode 100644
> index 000000000000..a84c39105f28
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-offset-err-1.s
> @@ -0,0 +1,15 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + stg %r11,88(%r15)
> + .cfi_rel_offset 11, 88
> + stg %r14,112(%r15)
> + .cfi_rel_offset 14, 112
> + la %r11,0
> + la %r14,0
> +.Lreturn:
> + lg %r14,112(%r15)
> + .cfi_restore 14
> + lg %r11,88(%r15)
> + .cfi_restore 11
> + br %r14
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.d
> new file mode 100644
> index 000000000000..7f1acd8c5d05
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - FP and then RA saved in register
> +#as: --gsframe
> +#warning: FP register 11 in .cfi_register
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.s
> new file mode 100644
> index 000000000000..48b01ac5f57b
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-1.s
> @@ -0,0 +1,15 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + ldgr %f2,%r11
> + .cfi_register 11, 17
> + ldgr %f0,%r14
> + .cfi_register 14, 16
> + la %r11,0
> + la %r14,0
> +.Lreturn:
> + lgdr %r14,%f0
> + .cfi_restore 14
> + lgdr %r11,%f2
> + .cfi_restore 11
> + br %r14
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.d
> new file mode 100644
> index 000000000000..6573d01b997b
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.d
> @@ -0,0 +1,15 @@
> +#name: SFrame generation on s390x - RA and then FP saved in register
> +#as: --gsframe
> +#warning: RA register 14 in .cfi_register
> +#objdump: --sframe=.sframe
> +#...
> +Contents of the SFrame section .sframe:
> +
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: NONE
> + Num FDEs: 0
> + Num FREs: 0
> +
> +#pass
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.s
> new file mode 100644
> index 000000000000..1d4497178ada
> --- /dev/null
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-s390x-fpra-register-err-2.s
> @@ -0,0 +1,15 @@
> + .cfi_sections .sframe
> + .cfi_startproc
> + ldgr %f0,%r14
> + .cfi_register 14, 16
> + ldgr %f2,%r11
> + .cfi_register 11, 17
> + la %r11,0
> + la %r14,0
> +.Lreturn:
> + lgdr %r11,%f2
> + .cfi_restore 11
> + lgdr %r14,%f0
> + .cfi_restore 14
> + br %r14
> + .cfi_endproc
> diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp b/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
> index 341a56a9eab2..df48cd143fd6 100644
> --- a/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
> +++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
> @@ -64,7 +64,8 @@ proc gas_x86_64_check { } {
> }
>
> # common tests
> -if { ([istarget "x86_64-*-*"] || [istarget "aarch64*-*-*"]) \
> +if { ([istarget "x86_64-*-*"] || [istarget "aarch64*-*-*"] ||
Nit: Follow the "No Trailing operator" rule here too?
> + [istarget "s390x-*-*"]) \
> && [gas_sframe_check] } then {
>
> global ASFLAGS
> @@ -109,3 +110,16 @@ if { [istarget "aarch64*-*-*"] && [gas_sframe_check] } then {
> run_dump_test "cfi-sframe-aarch64-4"
> run_dump_test "cfi-sframe-aarch64-pac-ab-key-1"
> }
> +
> +# s390x specific tests
> +if { [istarget "s390x*-*-*"] && [gas_sframe_check] } then {
> + run_dump_test "cfi-sframe-s390x-1"
> + run_dump_test "cfi-sframe-s390x-2"
> + run_dump_test "cfi-sframe-s390x-err-1"
> + run_dump_test "cfi-sframe-s390x-err-2"
> + run_dump_test "cfi-sframe-s390x-err-3"
> + run_dump_test "cfi-sframe-s390x-fpra-offset-1"
> + run_dump_test "cfi-sframe-s390x-fpra-offset-err-1"
> + run_dump_test "cfi-sframe-s390x-fpra-register-err-1"
> + run_dump_test "cfi-sframe-s390x-fpra-register-err-2"
> +}
> diff --git a/include/sframe.h b/include/sframe.h
> index a965e23bdd18..a87d6d491a2f 100644
> --- a/include/sframe.h
> +++ b/include/sframe.h
> @@ -93,6 +93,7 @@ extern "C"
> #define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 /* AARCH64 big endian. */
> #define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 /* AARCH64 little endian. */
> #define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 /* AMD64 little endian. */
> +#define SFRAME_ABI_S390X_ENDIAN_BIG 4 /* s390x big endian. */
>
> /* SFrame FRE types. */
> #define SFRAME_FRE_TYPE_ADDR1 0
> @@ -190,7 +191,7 @@ typedef struct sframe_func_desc_entry
> - 2-bits: Unused.
> ------------------------------------------------------------------------
> | Unused | PAC auth A/B key (aarch64) | FDE type | FRE type |
> - | | Unused (amd64) | | |
> + | | Unused (amd64, s390x) | | |
> ------------------------------------------------------------------------
> 8 6 5 4 0 */
> uint8_t sfde_func_info;
> @@ -248,7 +249,7 @@ typedef struct sframe_fre_info
> - 1 bit: Mangled RA state bit (aarch64 only).
> ----------------------------------------------------------------------------------
> | Mangled-RA (aarch64) | Size of offsets | Number of offsets | base_reg |
> - | Unused (amd64) | | | |
> + | Unused (amd64, s390x)| | | |
> ----------------------------------------------------------------------------------
> 8 7 5 1 0
>
> @@ -274,7 +275,7 @@ typedef struct sframe_fre_info
>
> /* SFrame Frame Row Entry definitions.
>
> - Used for both AMD64 and AARCH64.
> + Used for AMD64, AARCH64, and s390x.
>
> An SFrame Frame Row Entry is a self-sufficient record which contains
> information on how to generate the stack trace for the specified range of
> @@ -342,6 +343,10 @@ typedef struct sframe_frame_row_entry_addr4
> #define SFRAME_FRE_TYPE_ADDR4_LIMIT \
> (1ULL << ((SFRAME_FRE_TYPE_ADDR4 * 2) * 8))
>
> +/* On s390x, the CFA is defined as SP at call site + 160. Therefore the
> + SP value offset from CFA is -160. */
> +#define SFRAME_S390X_SP_VAL_OFFSET (-160)
> +
> #ifdef __cplusplus
> }
> #endif
> diff --git a/ld/testsuite/ld-s390/s390.exp b/ld/testsuite/ld-s390/s390.exp
> index 88b1d1699941..00d40f8d9623 100644
> --- a/ld/testsuite/ld-s390/s390.exp
> +++ b/ld/testsuite/ld-s390/s390.exp
> @@ -146,4 +146,8 @@ if { ([istarget "s390-*-*"] || [istarget "s390x-*-*"]) } {
>
> if [istarget "s390x-*-*"] {
> run_ld_link_tests $s390xtests
> +
> + if { ![skip_sframe_tests] } {
> + run_dump_test "sframe-simple-1"
> + }
> }
> diff --git a/ld/testsuite/ld-s390/sframe-bar.s b/ld/testsuite/ld-s390/sframe-bar.s
> new file mode 100644
> index 000000000000..f7075697d1e3
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/sframe-bar.s
> @@ -0,0 +1,21 @@
> + .text
> + .globl bar
> + .type bar, @function
> +bar:
> + .cfi_startproc
> + stmg %r14,%r15,112(%r15)
> + .cfi_rel_offset %r14, 112
> + .cfi_rel_offset %r15, 120
> + lay %r15,-160(%r15)
> + .cfi_adjust_cfa_offset 160
> + clgfi %r2,1000
> + jle .Lreturn
> + brasl %r14,foo@PLT
> +.Lreturn:
> + lay %r15,160(%r15)
> + .cfi_adjust_cfa_offset -160
> + lg %r14,112(%r15)
> + .cfi_restore %r14
> + br %r14
> + .cfi_endproc
> + .size bar, .-bar
> diff --git a/ld/testsuite/ld-s390/sframe-foo.s b/ld/testsuite/ld-s390/sframe-foo.s
> new file mode 100644
> index 000000000000..75657e93e33b
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/sframe-foo.s
> @@ -0,0 +1,9 @@
> + .text
> + .globl foo
> + .type foo, @function
> +foo:
> + .cfi_startproc
> + msgfi %r2,42
> + br %r14
> + .cfi_endproc
> + .size foo, .-foo
> diff --git a/ld/testsuite/ld-s390/sframe-simple-1.d b/ld/testsuite/ld-s390/sframe-simple-1.d
> new file mode 100644
> index 000000000000..4df5d492f01e
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/sframe-simple-1.d
> @@ -0,0 +1,30 @@
> +#as: --gsframe
> +#source: sframe-foo.s
> +#source: sframe-bar.s
> +#objdump: --sframe=.sframe
> +#ld: -shared --no-rosegment
> +#name: SFrame simple link
> +
> +.*: +file format .*
> +
> +Contents of the SFrame section .sframe:
> + Header :
> +
> + Version: SFRAME_VERSION_2
> + Flags: SFRAME_F_FDE_SORTED
> + Num FDEs: 2
> + Num FREs: 6
> +
> + Function Index :
> +
> + func idx \[0\]: pc = 0x228, size = 8 bytes
> + STARTPC +CFA +FP +RA +
> + 0+228 +sp\+160 +u +u +
> +
> + func idx \[1\]: pc = 0x230, size = 42 bytes
> + STARTPC +CFA +FP +RA +
> + 0+230 +sp\+160 +u +u +
> + 0+236 +sp\+160 +u +c-48 +
> + 0+23c +sp\+320 +u +c-48 +
> + 0+252 +sp\+160 +u +c-48 +
> + 0+258 +sp\+160 +u +u +
> diff --git a/libsframe/doc/sframe-spec.texi b/libsframe/doc/sframe-spec.texi
> index ae115705ca73..62040c3fa64f 100644
> --- a/libsframe/doc/sframe-spec.texi
> +++ b/libsframe/doc/sframe-spec.texi
> @@ -79,8 +79,8 @@ The SFrame stack trace information is provided in a loaded section, known as the
> @code{.sframe} section. When available, the @code{.sframe} section appears in
> a new segment of its own, PT_GNU_SFRAME.
>
> -The SFrame format is currently supported only for select ABIs, namely, AMD64
> -and AAPCS64.
> +The SFrame format is currently supported only for select ABIs, namely, AMD64,
> +AAPCS64, and s390x.
>
Sorry, but I just realised this recently: I would also recommend you
put an entry in the section "Changes from Version 1 to Version 2" to add
s390x support to the specification.
Something like:
Add a new ABI/arch identifier SFRAME_ABI_S390X_ENDIAN_BIG. Other
backward compatible changes including helper definitions related to CFA
offset adjustment on s390x, and encoding and decoding of FP/RA save in
register on s390x have been added incrementally to SFrame version 2 only.
I leave this to your best judgement on whether to include this now or
later as a separate commit after the series.
> A portion of the SFrame format follows an unaligned on-disk representation.
> Some data structures, however, (namely the SFrame header and the SFrame
> @@ -401,6 +401,10 @@ in the format.
> @item @code{SFRAME_ABI_AMD64_ENDIAN_LITTLE}
> @tab 3 @tab AMD64 little-endian
>
> +@tindex SFRAME_ABI_S390X_ENDIAN_BIG
> +@item @code{SFRAME_ABI_S390X_ENDIAN_BIG}
> +@tab 4 @tab s390x big-endian
> +
> @end multitable
>
> The presence of an explicit identification of ABI/arch in SFrame may allow
> @@ -772,6 +776,7 @@ auxiliary SFrame header, etc., if used, must also be outlined here.
> @menu
> * AMD64::
> * AArch64::
> +* s390x::
> @end menu
>
> @node AMD64
> @@ -828,6 +833,51 @@ Hence, in summary:
> @item 3 @tab FP = CFA + offset3
> @end multitable
>
> +@node s390x
> +@section s390x
> +
> +A stack tracer implementation must initialize the SP to the designated SP
> +register value, the FP to the preferred FP register value, and the RA to the
> +designated RA register value in the topmost stack frame of the callchain. This
> +is required, as either the SP or FP is used as CFA base register and as the FP
> +and/or RA are not necessarily saved on the stack. For RA this may only be the
> +case in the topmost stack frame of the callchain. For FP this may be the case
> +in any stack frame.
> +
> +Irrespective of the ABI, the first stack offset is always used to locate the
> +CFA, by interpreting it as: CFA = @code{BASE_REG} + offset1.
> +The identification of the @code{BASE_REG} is done by using the
> +@code{fre_cfa_base_reg_id} field in the SFrame FRE info word.
> +
> +The (64-bit) s390x ELF ABI does not mandate the precise location in a function
> +where the return address (RA) and frame pointer (FP) are saved, if at all.
> +Hence the need to track RA in the SFrame stack trace format. As RA is being
> +tracked in this ABI, the second stack offset is always used to locate the RA
> +stack slot, by interpreting it as: RA = CFA + offset2. RA remains unchanged,
> +if the offset is not available. The third stack offset is used to locate the
> +FP stack slot, by interpreting it as: FP = CFA + offset3. FP remains unchanged,
> +if the offset is not available.
> +It is recommended that a stack tracer implementation performs the required
> +checks to ensure that RA remains unchanged only for the topmost stack frame
> +in the callchain.
> +
I find the last statement difficult to follow. In light of the patches
04/11 and 05/11, which allow RA to be saved in say FPR, or RA to be not
saved on stack respectively, I am not sure I fully grasp the scope of
the statement "RA remains unchanged only for the topmost stack frame in
the callchain".
> +Given the nature of things, the number of stack offsets seen on s390x per
> +SFrame FRE is either 1, 2, or 3.
> +
> +Hence, in summary:
> +
> +@multitable {Offset ID} {Interpretation in s390x in X}
> +@headitem Offset ID @tab Interpretation in s390x
> +@item 1 @tab CFA = @code{BASE_REG} + offset1
> +@item 2 @tab RA = CFA + offset2
> +@item 3 @tab FP = CFA + offset3
> +@end multitable
> +
> +The s390x ELF ABI defines the CFA as stack pointer (SP) at call site +160. The
> +SP can therefore be obtained using the SP value offset from CFA
> +@code{SFRAME_S390X_SP_VAL_OFFSET} of -160 as follows:
> +SP = CFA + @code{SFRAME_S390X_SP_VAL_OFFSET}
> +
> @node Generating Stack Traces using SFrame
> @appendix Generating Stack Traces using SFrame
>
> @@ -891,7 +941,7 @@ SFrame section.
> fp_offset = sframe_fre_get_fp_offset (fre);
>
> cfa = base_reg_val + cfa_offset;
> - next_frame->sp = cfa;
> + next_frame->sp = cfa [+ SFRAME_S390X_SP_VAL_OFFSET on s390x];
>
> ra_stack_loc = cfa + ra_offset;
> // Get the address stored in the stack location.
> diff --git a/libsframe/sframe.c b/libsframe/sframe.c
> index b18ea773b8b5..d7acfeccdc24 100644
> --- a/libsframe/sframe.c
> +++ b/libsframe/sframe.c
> @@ -165,6 +165,7 @@ need_swapping (int endian)
> case SFRAME_ABI_AMD64_ENDIAN_LITTLE:
> return !is_little;
> case SFRAME_ABI_AARCH64_ENDIAN_BIG:
> + case SFRAME_ABI_S390X_ENDIAN_BIG:
> return is_little;
> default:
> break;
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